The co-occurrence of 2 similar species depends on their ability to occupy different ecological niches. Here, we compared the consistency of different aspects of foraging behavior in 2 cooccurring harvester ant species...The co-occurrence of 2 similar species depends on their ability to occupy different ecological niches. Here, we compared the consistency of different aspects of foraging behavior in 2 cooccurring harvester ant species （Messor ebeninus and Messor arenarius）, under field conditions. The 2 species are active concomitantly and display a similar diet, but M. arenarius features smaller colonies, larger workers on average, and a broader range of foraging strategies than M. ebeninus. We characterized the flora in the 2 species＇ natural habitat, and detected a nesting preference by M. arenarius for more open, vegetation-free microhabitats than those preferred by M. ebeninus. Next, we tested the food preference of foraging colonies by presenting 3 non-native seed types. Messor arenarius was more selective in its food choice. Colonies were then offered 1 type of seeds over 3 days in different spatial arrangements from the nest entrance （e.g., a seed plate close to the nest entrance, a seed plate blocked by an obstacle, or 3 plates placed at increasing distances from the nest entrance）. While both species were consistent in their foraging behavior, expressed as seed collection, under different treatments over time, M. ebeninus was more consistent than M. arenarius. These differences between the species may be expxained by their different colony size, worker size, and range of foraging strategies, among other factors. We suggest that the differences in foraging, such as in food preference and behavioral consistency while foraging, could contribute to the co-occurrence of these 2 species in a similar habitat.展开更多
Pit-building antlions and wormlions are 2 distantly-related insect species, whose larvae construct pits in loose soil to trap small arthropod prey. This convergent evolution of natural histories has led to additional ...Pit-building antlions and wormlions are 2 distantly-related insect species, whose larvae construct pits in loose soil to trap small arthropod prey. This convergent evolution of natural histories has led to additional similarities in their natural history and ecology, and thus, these 2 species encounter similar abiotic stress （such as periodic starvation） in their natural habitat. Here, we measured the cold tolerance of the 2 species and examined whether recent feeding or food deprivation, as well as body composition （body mass and lipid content） and condition （quantified as mass-to-size residuals） affect their cold tolerance. In contrast to other insects, in which food deprivation either enhanced or impaired cold tolerance, prolonged fasting had no effect on the cold tolerance of either species, which had similar cold tolerance. The 2 species differed, however, in how cold tolerance related to body mass and lipid content： although body mass was positively correlated with the wormlion cold tolerance, lipid content was a more reliable predictor of cold tolerance in the antlions. Cold tolerance also underwent greater change with ontogeny in wormlions than in antlions. We discuss possible reasons for this lack of effect of food deprivation on both species＇ cold tolerance, such as their high starvation tolerance （being sit-and-wait predators）.展开更多
Urban habitats differ from their natural surroundings in various aspects,such as a higher temperature and a distinct species composition.It is therefore not surprising that animal behavior too differs between these ha...Urban habitats differ from their natural surroundings in various aspects,such as a higher temperature and a distinct species composition.It is therefore not surprising that animal behavior too differs between these habitat types.We studied the foraging and habitat selection behavior of a pit-building predator,a wormlion,originating from either an urban or a more natural site.Wormlions occur in nature under structures that provide shelter from sunlight and rain,such as caves,and are also common in cities,occurring under artificial shelters.Wormlions construct pittraps to hunt arthropods,and the pits constructed by urban wormlions were larger than those constructed by wormlions from caves.Urban wormlions responded faster to prey falling into their pit,probably leading to a higher capture success.We suggest that these 2 findings indicate the higher investment of urban wormlions in foraging,resulting from the higher abundance of potential prey in the city.Urban wormlions were choosier regarding their preferred microhabitat.While both fine sand and shaded microhabitats were preferred by wormlions,urban wormlions demonstrated a greater preference for such conditions.We suggest that relocation is more likely to lead wormlions in cities to find microhabitats of a higher quality compared with wormlions inhabiting caves.This is probably due to the larger areas in the city available for wormlions.Wormlions from the caves possessed more lipids,suggesting that they employ a conservative growth strategy,intended to contend with the uncertainty of prey arrival,in contrast to the city,where potential prey are more abundant.展开更多
Wormlions are small fly larvae that dig pits in loose soil to trap their prey. Similar to other trapbuilding predators, like spiders and antlions, they depend on the habitat structure for successful trap construction ...Wormlions are small fly larvae that dig pits in loose soil to trap their prey. Similar to other trapbuilding predators, like spiders and antlions, they depend on the habitat structure for successful trap construction and prey catch. We examined whether sites at which wormlions are present differ in sand depth and particle size from nearby sites, at which wormlions are absent. Next, in the laboratory we manipulated both sand depth and type (fine vs. coarse) to determine their joint effect on microhabitat pref ere nee, the size of the con structed pit, wormlion movement, and their latency to respond to prey. We expected better performance by wormlions in fine and deep sand, and the sand in wormlions' natural sites to be finer and deeper. However, in only partial agreement with our expectations, wormlion sites featured finer sand but not deeper sand. In the laboratory, wormlions preferred both fine and deep sand, and moved more in shallow and coarse sand, which we interpret as an attempt to relocate away from unfavorable conditions. However, only deep sand led to larger pits being constructed and to a faster response to prey. The preference for fine sand could, therefore, be related to other ben efits that sand provides. Fin ally, body mass was a domi nant factor, interacting with the preference for both deep and fine sand: deep over shallow sand was more favored by large wormlions and fine over coarse sand by smaller ones. Our results suggest that several factors should be incorporated when studying microhabitat selection.展开更多
Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of ...Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of the literature revealed the frequent occurrence of injury in ants and its various causes.We examined whether leg or antenna injury impacts food-discovery time and reduces the likelihood of reaching food in workers of the desert ant Cataglyphis niger.We examined the search-related consequences of injury in groups of either 4 or 8 workers searching for food in a short arena,a long arena,and a maze.We conducted a small field survey to evaluate the prevalence of injury in the studied population.Finally,we compared the survival rates of injured versus uninjured workers in the laboratory.Injury was common in the field,with almost 9%of the workers collected out of the nest,found to be injured.Injured workers survived shorter than uninjured ones and there was a positive link between injury severity and survival.However,we could not detect an effect of injury on any of the searching-related response variables,neither in the arenas nor in the mazes tested.We suggest that workers that survive such injury are only moderately affected by it.展开更多
Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and ...Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and smell to foraging and maze exploration under laboratory conditions using Cataglyphis desert ants as a model.Foraging intensity,measured as the number of workers entering the maze and arriving at the target as well as target arrival time,were greater when food,blue light,or both were offered or presented in contrast to a control.Workers trained to forage for a combined food and light cue elevated their foraging intensity with experience.However,foraging intensity was not higher when using both cues simultaneously than in either one of the two alone.Following training,we split between the two cues and moved either the food or the blue light to the opposite maze corner.This manipulation impaired foraging success by either leading to fewer workers arriving at the target cell(when the light stayed and the food was moved)or to more workers arriving at the opposite target cell,empty of food(when the food stayed and the light was moved).This result indicates that ant workers use both senses when foraging for food and readily associate light with food.展开更多
Most habitats in nature are heterogeneous, incorporating favorable and unfavorable microhabitats for different animals, based on their ecological niche. Unsuitable microhabitats have negative consequences for individu...Most habitats in nature are heterogeneous, incorporating favorable and unfavorable microhabitats for different animals, based on their ecological niche. Unsuitable microhabitats have negative consequences for individual growth and survival. Animals, therefore, should fine-tune their location within the habitat by dispersing away from such microhabitats. We studied the suitability of different constant microhabitat conditions for wormlion larvae, a trap-building predator, tested in groups under laboratory conditions. Wormlions construct pit-traps in loose soil and capture small arthropod prey. As wormlions occur in high densities in nature, testing in groups is thus more indicative of their natural behavior than testing individuals. Wormlions responded strongly to biotic conditions--high conspecific density, starvation, and large body mass of conspecifics--by either increasing pit-relocation events or moving away from the microhabitat center to the periphery of the arena, probably opting for a way out. In other instances, individuals increased their distance to the nearest neighbor, thereby changing the spatial pattern toward a more regular pattern, potentially indicating interference competition. The only abiotic condition apparently perceived by wormlions as unsuitable was shallow sand, which led to frequent relocations. The two other abiotic factors--illumination and sand particle size--had no observable effect on behavior, although wormlions in nature always occur under shade in fine sand, and prefer both shade and fine sand particle size under laboratory conditions when given a choice. Under the fine spatial scale of the present experiment, biotic factors appear to be more influential than abiotic ones.展开更多
Movement plays a crucial role in animal behavior.However,despite the preva-lence of uneven terrains in nature,many movement studies are conducted in arenas with smooth substrates.This discrepancy raises questions abou...Movement plays a crucial role in animal behavior.However,despite the preva-lence of uneven terrains in nature,many movement studies are conducted in arenas with smooth substrates.This discrepancy raises questions about the ecological validity of such experiments.To address this gap,we investigated the effect of rough substrates on move-ment properties using the red flour beetle(Tribolium castaneum)as a model organism.Our findings revealed significant variations in movement behavior between rough and smooth substrates.Notably,beetles traveled longer distances on smooth surfaces com-pared to sandpaper and loose sand.Moreover,variations in step size were influenced by substrate treatment,with the highest values observed on sand and sandpaper treatments.The proportion of time spent standing still also showed sensitivity to substrate condi-tions.The interaction between substrate properties and beetle sex further influenced sev-eral movement properties.Even the spatial configuration of rough and smooth areas in the arena had an impact on beetle movement,with areas along the arena perimeter exhibiting a stronger effect.These results highlight the impact of uneven terrain on beetle movement,underscoring the importance of considering environmental conditions when designing ex-perimental setups.Here,this refers to the substrate on which animals move,but it may refer to other conditions,such as the test arena size and shape,temperature,humidity,and illumination.Failure to account for these background environmental conditions may re-sult in inadvertently examining the interaction of the tested animals with these conditions,rather than focusing on the effect of the treatments applied in the experiment.展开更多
Circadian rhythms are self-sustained endogenous oscillations that are found in all living organisms.In insects,circadian rhythms control a wide variety of behavioral and physiological processes,including feeding,locom...Circadian rhythms are self-sustained endogenous oscillations that are found in all living organisms.In insects,circadian rhythms control a wide variety of behavioral and physiological processes,including feeding,locomotion,mating,and metabolism.While the role of circadian rhythms in adult insects is well-understood,it is largely unexplored in larvae.This study investigates the potential for larval synchronized activity in the red flour beetle(Tribolium castaneum),a species exhibiting solitary and aggregation phases.We hypothesized that,similar to adults,larvae would exhibit a daily activity pattern governed by an endogenous circadian clock.We further predicted that the transition between the solitary and gregarious phases extends to unique temporal activity patterns.Our results revealed unique timekeeper gene expression in larvae,leading to a distinct daily rhythm characterized by nocturnal activity.Cues indicating on potential cannibalism did not change daily activity peak.However,the absence of these cues significantly reduced the proportion of rhythmic larvae and led to higher variation in peak activity,highlighting the crucial role of social interactions in shaping their rhythmicity.This study sheds light on the evolution and function of larval synchronization in group-living insects,offering novel insights into this complex behavior.展开更多
Movement is an important animal behavior contributing to reproduction and survival.Animal movement is often examined in arenas or enclosures under laboratory conditions.We used the red flour beetle(Tribolium castaneum...Movement is an important animal behavior contributing to reproduction and survival.Animal movement is often examined in arenas or enclosures under laboratory conditions.We used the red flour beetle(Tribolium castaneum)to examine here the effect of the arena size,shape,number of barriers,access to the arena's center,and illumination on six movement properties.We demonstrate great differences among arenas.For example,the beetles moved over longer distances in clear arenas than in obstructed ones.Movement along the arena's perimeter was greater in smaller arenas than in larger ones.Movement was more directional in round arenas than in rectangular ones.In general,the beetles stopped moving closer to the perimeter and closer to corners(in the square and rectangular arenas)than expected by chance.In some cases,the arena properties interacted with the beetle sex to affect several movement properties.All these suggest that arena properties might also interact with experimental manipulations to affect the outcome of studies and lead to results specific to the arena used.In other words,instead of examining animal movement,we in fact examine the animal interaction with the arena structure.Caution is therefore advised in interpreting the results of studies on movement in arenas under laboratory conditions and we recommend paying attention also to barriers or obstacles in field experiments.For instance,movement along the arena's perimeter is often interpreted as centrophobism or thigmotaxis but the results here show that such movement is arena dependent.展开更多
Animals are exposed in nature to a variety ofstressors.While stress is generally harmful,mild stress can also be beneficial and contribute to reproduction and survival.We studied the effect of five cold shock events v...Animals are exposed in nature to a variety ofstressors.While stress is generally harmful,mild stress can also be beneficial and contribute to reproduction and survival.We studied the effect of five cold shock events versus a single cold shock and a control group, representing three levels of stress (harsh,mild,and no stress),on behavioral,physiological, and life-history traits of the red flour beetle (Tribolium castaneum,Herbst 1797).Beetles exposed to harsh cold stress were less active than a control group:they moved less and failed more frequently to detect a food patch.Their probability to mate was also lower. Beetle pairs exposed to harsh cold stress frequently failed to reproduce at all,and if reproducing,females laid fewer eggs,which were,as larvae in mid-development,smaller than those in the control group.However,harsh cold stress led to improved female starvation tolerance,probably due to enhanced lipid accumulation.Harsh cold shock also improved tolerance to an additional cold shock compared to the control.Finally,a single cold shock event negatively affected fewer measured response variables than the harsh cold stress, but also enhanced neither starvation tolerance nor tolerance to an additional cold shock. The consequences of a harsher cold stress are thus not solely detrimental but might even enhance survival under stressful conditions.Under benign conditions,nevertheless,harsh stress impedes beetle performance.The harsh stress probably shifted the balance point of the survival-reproduction trade-off,a shift that did not take place following exposure to mild stress.展开更多
Animals often search for food more efficiently with experience.However,the contribution of experience toforaging success under direct competition has rarelybeen examined.Here we used colonies of an individually foragi...Animals often search for food more efficiently with experience.However,the contribution of experience toforaging success under direct competition has rarelybeen examined.Here we used colonies of an individually foraging desert ant to investigate the value of spatial experience.First,we trained worker groups of equal numbers to solve either a complex or a simple maze.We then tested pairs of both groups against one another in reaching a food reward.This task required solving the same complex maze that one of the groups had been trained in,to determine which group would exploit better the food reward.The worker groups previously trained in the complex mazes reached the food reward faster and more of these workers fed on the food than those trained in simple mazes,but only in the intermediate size group.To determine the relative importance of group size versus spatial experience in exploiting food patches,we then tested smaller trained worker groups against larger untrained ones.The larger groups outcompeted the smaller ones,despite the latter's advantage of spatial experience.The contribution of spatial experience,as found here,appears to be small,and depends on group size:an advantage of a few workers of the untrained group over the trained group negates its benefits.展开更多
Ongoing climate change affects various aspects of an animal＇s life, with impor- tant effects on distribution range and phenology. The relationship between global warming and body size changes in mammals and birds has...Ongoing climate change affects various aspects of an animal＇s life, with impor- tant effects on distribution range and phenology. The relationship between global warming and body size changes in mammals and birds has been widely studied, with most find- ings indicating a decline in body size over time. Nevertheless, little data exist on similar size change patterns of invertebrates in general and insects in particular, and it is unclear whether insects should decrease in size or not with climate warming. We measured over 4000 beetle specimens, belonging to 29 beetle species in 8 families, collected in Israel during the last 100 years. The sampled species are all herbivorous. We examined whether beetle body size had changed over the years, while also investigating the relationships between body size and annual temperature, precipitation, net primary productivity （NPP） at the collection site and collection month. None of the environmental variables, including the collection year, was correlated with the size of most of the studied beetle species, while there were strong interactions of all variables with species. Our results, though mostly neg- ative, suggest that the effect of climate change on insect body size is species-specific and by no means a general macro-ecological rule. They also suggest that the intrapopulation variance in body size of insects collected as adults in the field is large enough to conceal intersite environmental effects on body size, such as the effect of temperature and NPE展开更多
Antlions and wormlions are distantly related insect taxa,both digging pits in loose soil and ambushing arthropod prey.Their hunting method,which is rare in the animal kingdom,is a clear example of convergent evolution...Antlions and wormlions are distantly related insect taxa,both digging pits in loose soil and ambushing arthropod prey.Their hunting method,which is rare in the animal kingdom,is a clear example of convergent evolution.There is little research directly comparing the 2 pit-building taxa.Using the same experimental platform to investigate how they respond to biotic and abiotic environmental factors enables an examination of their convergence and its limits.We investigated the response of antlions and wormlions to 3 factors common in their daily life:disturbance to the pits,prey arrival,and conspecific competitors.Although both increased the pit size following disturbance,wormlions increased it faster than antlions.Antlions responded to prey faster than wormlions,but wormlions im-proved their response time over days.The most diverging response was toward conspecifics.Whereas antlions relocated their pits fast in response to increasing conspecific density,wormlions never relocated.We suggest expla-nations for the behavioral differences between the taxa.Our results imply that despite the similar hunting method of the 2 taxa they may differ greatly in their behavior,which in turn might have consequences for their habitat use and population dynamics.展开更多
Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes ...Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes with the acquisition of new information,whereas“retroactive interference”suggests that newly gathered information interferes with already existing information.Our goal was to examine the possible effect of both mechanisms in the desert ant Cataglyphis niger,which does not use pheromone recruitment,when learning spatial information while searching for food in a maze.Our experiment indicated that neither proactive nor retroactive interference took place in this system although this awaits confirmation with individual-level learning assays.Rather,the ants’persistence or readiness to search for food grew with successive runs in the maze.Elevated persistence led to more ant workers arriving at the food when retested a day later,even if the maze was shifted between runs.We support thisfinding in a second experiment,where ant workers reached the food reward at the maze end in higher numbers after encountering food in the maze entry compared to a treatment,in which food was present only at the maze end.This result suggests that spatial learning and search persistence are 2 parallel behavioral mechanisms,both assisting foraging ants.We suggest that their relative contribution should depend on habitat complexity.展开更多
文摘The co-occurrence of 2 similar species depends on their ability to occupy different ecological niches. Here, we compared the consistency of different aspects of foraging behavior in 2 cooccurring harvester ant species （Messor ebeninus and Messor arenarius）, under field conditions. The 2 species are active concomitantly and display a similar diet, but M. arenarius features smaller colonies, larger workers on average, and a broader range of foraging strategies than M. ebeninus. We characterized the flora in the 2 species＇ natural habitat, and detected a nesting preference by M. arenarius for more open, vegetation-free microhabitats than those preferred by M. ebeninus. Next, we tested the food preference of foraging colonies by presenting 3 non-native seed types. Messor arenarius was more selective in its food choice. Colonies were then offered 1 type of seeds over 3 days in different spatial arrangements from the nest entrance （e.g., a seed plate close to the nest entrance, a seed plate blocked by an obstacle, or 3 plates placed at increasing distances from the nest entrance）. While both species were consistent in their foraging behavior, expressed as seed collection, under different treatments over time, M. ebeninus was more consistent than M. arenarius. These differences between the species may be expxained by their different colony size, worker size, and range of foraging strategies, among other factors. We suggest that the differences in foraging, such as in food preference and behavioral consistency while foraging, could contribute to the co-occurrence of these 2 species in a similar habitat.
文摘Pit-building antlions and wormlions are 2 distantly-related insect species, whose larvae construct pits in loose soil to trap small arthropod prey. This convergent evolution of natural histories has led to additional similarities in their natural history and ecology, and thus, these 2 species encounter similar abiotic stress （such as periodic starvation） in their natural habitat. Here, we measured the cold tolerance of the 2 species and examined whether recent feeding or food deprivation, as well as body composition （body mass and lipid content） and condition （quantified as mass-to-size residuals） affect their cold tolerance. In contrast to other insects, in which food deprivation either enhanced or impaired cold tolerance, prolonged fasting had no effect on the cold tolerance of either species, which had similar cold tolerance. The 2 species differed, however, in how cold tolerance related to body mass and lipid content： although body mass was positively correlated with the wormlion cold tolerance, lipid content was a more reliable predictor of cold tolerance in the antlions. Cold tolerance also underwent greater change with ontogeny in wormlions than in antlions. We discuss possible reasons for this lack of effect of food deprivation on both species＇ cold tolerance, such as their high starvation tolerance （being sit-and-wait predators）.
基金We thank the Israel Science Foundation(Grant no.442/16)for funding this studyI.S.would also like to thank the Humboldt Foundation,Germany,for its support.
文摘Urban habitats differ from their natural surroundings in various aspects,such as a higher temperature and a distinct species composition.It is therefore not surprising that animal behavior too differs between these habitat types.We studied the foraging and habitat selection behavior of a pit-building predator,a wormlion,originating from either an urban or a more natural site.Wormlions occur in nature under structures that provide shelter from sunlight and rain,such as caves,and are also common in cities,occurring under artificial shelters.Wormlions construct pittraps to hunt arthropods,and the pits constructed by urban wormlions were larger than those constructed by wormlions from caves.Urban wormlions responded faster to prey falling into their pit,probably leading to a higher capture success.We suggest that these 2 findings indicate the higher investment of urban wormlions in foraging,resulting from the higher abundance of potential prey in the city.Urban wormlions were choosier regarding their preferred microhabitat.While both fine sand and shaded microhabitats were preferred by wormlions,urban wormlions demonstrated a greater preference for such conditions.We suggest that relocation is more likely to lead wormlions in cities to find microhabitats of a higher quality compared with wormlions inhabiting caves.This is probably due to the larger areas in the city available for wormlions.Wormlions from the caves possessed more lipids,suggesting that they employ a conservative growth strategy,intended to contend with the uncertainty of prey arrival,in contrast to the city,where potential prey are more abundant.
基金the Israel Science Foundation (grant no. 442/16) for funding this study.
文摘Wormlions are small fly larvae that dig pits in loose soil to trap their prey. Similar to other trapbuilding predators, like spiders and antlions, they depend on the habitat structure for successful trap construction and prey catch. We examined whether sites at which wormlions are present differ in sand depth and particle size from nearby sites, at which wormlions are absent. Next, in the laboratory we manipulated both sand depth and type (fine vs. coarse) to determine their joint effect on microhabitat pref ere nee, the size of the con structed pit, wormlion movement, and their latency to respond to prey. We expected better performance by wormlions in fine and deep sand, and the sand in wormlions' natural sites to be finer and deeper. However, in only partial agreement with our expectations, wormlion sites featured finer sand but not deeper sand. In the laboratory, wormlions preferred both fine and deep sand, and moved more in shallow and coarse sand, which we interpret as an attempt to relocate away from unfavorable conditions. However, only deep sand led to larger pits being constructed and to a faster response to prey. The preference for fine sand could, therefore, be related to other ben efits that sand provides. Fin ally, body mass was a domi nant factor, interacting with the preference for both deep and fine sand: deep over shallow sand was more favored by large wormlions and fine over coarse sand by smaller ones. Our results suggest that several factors should be incorporated when studying microhabitat selection.
文摘Injury is common in nature resulting,for example,from fighting,partial predation,or the wear of body parts.Injury is costly,expressed in impaired performance,failure in competition,and a shorter life span.A survey of the literature revealed the frequent occurrence of injury in ants and its various causes.We examined whether leg or antenna injury impacts food-discovery time and reduces the likelihood of reaching food in workers of the desert ant Cataglyphis niger.We examined the search-related consequences of injury in groups of either 4 or 8 workers searching for food in a short arena,a long arena,and a maze.We conducted a small field survey to evaluate the prevalence of injury in the studied population.Finally,we compared the survival rates of injured versus uninjured workers in the laboratory.Injury was common in the field,with almost 9%of the workers collected out of the nest,found to be injured.Injured workers survived shorter than uninjured ones and there was a positive link between injury severity and survival.However,we could not detect an effect of injury on any of the searching-related response variables,neither in the arenas nor in the mazes tested.We suggest that workers that survive such injury are only moderately affected by it.
基金We thank the German Research Foundation for funding this research project(DFG,grant no.FO 298/31-1).
文摘Foragers use several senses to locate food,and many animals rely on vision and smell.It is beneficial not to rely on a single sense,which might fail under certain conditions.We examined the contribution of vision and smell to foraging and maze exploration under laboratory conditions using Cataglyphis desert ants as a model.Foraging intensity,measured as the number of workers entering the maze and arriving at the target as well as target arrival time,were greater when food,blue light,or both were offered or presented in contrast to a control.Workers trained to forage for a combined food and light cue elevated their foraging intensity with experience.However,foraging intensity was not higher when using both cues simultaneously than in either one of the two alone.Following training,we split between the two cues and moved either the food or the blue light to the opposite maze corner.This manipulation impaired foraging success by either leading to fewer workers arriving at the target cell(when the light stayed and the food was moved)or to more workers arriving at the opposite target cell,empty of food(when the food stayed and the light was moved).This result indicates that ant workers use both senses when foraging for food and readily associate light with food.
文摘Most habitats in nature are heterogeneous, incorporating favorable and unfavorable microhabitats for different animals, based on their ecological niche. Unsuitable microhabitats have negative consequences for individual growth and survival. Animals, therefore, should fine-tune their location within the habitat by dispersing away from such microhabitats. We studied the suitability of different constant microhabitat conditions for wormlion larvae, a trap-building predator, tested in groups under laboratory conditions. Wormlions construct pit-traps in loose soil and capture small arthropod prey. As wormlions occur in high densities in nature, testing in groups is thus more indicative of their natural behavior than testing individuals. Wormlions responded strongly to biotic conditions--high conspecific density, starvation, and large body mass of conspecifics--by either increasing pit-relocation events or moving away from the microhabitat center to the periphery of the arena, probably opting for a way out. In other instances, individuals increased their distance to the nearest neighbor, thereby changing the spatial pattern toward a more regular pattern, potentially indicating interference competition. The only abiotic condition apparently perceived by wormlions as unsuitable was shallow sand, which led to frequent relocations. The two other abiotic factors--illumination and sand particle size--had no observable effect on behavior, although wormlions in nature always occur under shade in fine sand, and prefer both shade and fine sand particle size under laboratory conditions when given a choice. Under the fine spatial scale of the present experiment, biotic factors appear to be more influential than abiotic ones.
文摘Movement plays a crucial role in animal behavior.However,despite the preva-lence of uneven terrains in nature,many movement studies are conducted in arenas with smooth substrates.This discrepancy raises questions about the ecological validity of such experiments.To address this gap,we investigated the effect of rough substrates on move-ment properties using the red flour beetle(Tribolium castaneum)as a model organism.Our findings revealed significant variations in movement behavior between rough and smooth substrates.Notably,beetles traveled longer distances on smooth surfaces com-pared to sandpaper and loose sand.Moreover,variations in step size were influenced by substrate treatment,with the highest values observed on sand and sandpaper treatments.The proportion of time spent standing still also showed sensitivity to substrate condi-tions.The interaction between substrate properties and beetle sex further influenced sev-eral movement properties.Even the spatial configuration of rough and smooth areas in the arena had an impact on beetle movement,with areas along the arena perimeter exhibiting a stronger effect.These results highlight the impact of uneven terrain on beetle movement,underscoring the importance of considering environmental conditions when designing ex-perimental setups.Here,this refers to the substrate on which animals move,but it may refer to other conditions,such as the test arena size and shape,temperature,humidity,and illumination.Failure to account for these background environmental conditions may re-sult in inadvertently examining the interaction of the tested animals with these conditions,rather than focusing on the effect of the treatments applied in the experiment.
文摘Circadian rhythms are self-sustained endogenous oscillations that are found in all living organisms.In insects,circadian rhythms control a wide variety of behavioral and physiological processes,including feeding,locomotion,mating,and metabolism.While the role of circadian rhythms in adult insects is well-understood,it is largely unexplored in larvae.This study investigates the potential for larval synchronized activity in the red flour beetle(Tribolium castaneum),a species exhibiting solitary and aggregation phases.We hypothesized that,similar to adults,larvae would exhibit a daily activity pattern governed by an endogenous circadian clock.We further predicted that the transition between the solitary and gregarious phases extends to unique temporal activity patterns.Our results revealed unique timekeeper gene expression in larvae,leading to a distinct daily rhythm characterized by nocturnal activity.Cues indicating on potential cannibalism did not change daily activity peak.However,the absence of these cues significantly reduced the proportion of rhythmic larvae and led to higher variation in peak activity,highlighting the crucial role of social interactions in shaping their rhythmicity.This study sheds light on the evolution and function of larval synchronization in group-living insects,offering novel insights into this complex behavior.
文摘Movement is an important animal behavior contributing to reproduction and survival.Animal movement is often examined in arenas or enclosures under laboratory conditions.We used the red flour beetle(Tribolium castaneum)to examine here the effect of the arena size,shape,number of barriers,access to the arena's center,and illumination on six movement properties.We demonstrate great differences among arenas.For example,the beetles moved over longer distances in clear arenas than in obstructed ones.Movement along the arena's perimeter was greater in smaller arenas than in larger ones.Movement was more directional in round arenas than in rectangular ones.In general,the beetles stopped moving closer to the perimeter and closer to corners(in the square and rectangular arenas)than expected by chance.In some cases,the arena properties interacted with the beetle sex to affect several movement properties.All these suggest that arena properties might also interact with experimental manipulations to affect the outcome of studies and lead to results specific to the arena used.In other words,instead of examining animal movement,we in fact examine the animal interaction with the arena structure.Caution is therefore advised in interpreting the results of studies on movement in arenas under laboratory conditions and we recommend paying attention also to barriers or obstacles in field experiments.For instance,movement along the arena's perimeter is often interpreted as centrophobism or thigmotaxis but the results here show that such movement is arena dependent.
基金the People Programme (Marie Curie Actions)of the European Union's Seventh Framework Programme (FP7/2007-2013)under REA grant agreement no.333442the Israel Science Foundation (grant no.442/16)for funding this study.
文摘Animals are exposed in nature to a variety ofstressors.While stress is generally harmful,mild stress can also be beneficial and contribute to reproduction and survival.We studied the effect of five cold shock events versus a single cold shock and a control group, representing three levels of stress (harsh,mild,and no stress),on behavioral,physiological, and life-history traits of the red flour beetle (Tribolium castaneum,Herbst 1797).Beetles exposed to harsh cold stress were less active than a control group:they moved less and failed more frequently to detect a food patch.Their probability to mate was also lower. Beetle pairs exposed to harsh cold stress frequently failed to reproduce at all,and if reproducing,females laid fewer eggs,which were,as larvae in mid-development,smaller than those in the control group.However,harsh cold stress led to improved female starvation tolerance,probably due to enhanced lipid accumulation.Harsh cold shock also improved tolerance to an additional cold shock compared to the control.Finally,a single cold shock event negatively affected fewer measured response variables than the harsh cold stress, but also enhanced neither starvation tolerance nor tolerance to an additional cold shock. The consequences of a harsher cold stress are thus not solely detrimental but might even enhance survival under stressful conditions.Under benign conditions,nevertheless,harsh stress impedes beetle performance.The harsh stress probably shifted the balance point of the survival-reproduction trade-off,a shift that did not take place following exposure to mild stress.
基金funding this research project(DFGgrant no.FO 298/31-1).
文摘Animals often search for food more efficiently with experience.However,the contribution of experience toforaging success under direct competition has rarelybeen examined.Here we used colonies of an individually foraging desert ant to investigate the value of spatial experience.First,we trained worker groups of equal numbers to solve either a complex or a simple maze.We then tested pairs of both groups against one another in reaching a food reward.This task required solving the same complex maze that one of the groups had been trained in,to determine which group would exploit better the food reward.The worker groups previously trained in the complex mazes reached the food reward faster and more of these workers fed on the food than those trained in simple mazes,but only in the intermediate size group.To determine the relative importance of group size versus spatial experience in exploiting food patches,we then tested smaller trained worker groups against larger untrained ones.The larger groups outcompeted the smaller ones,despite the latter's advantage of spatial experience.The contribution of spatial experience,as found here,appears to be small,and depends on group size:an advantage of a few workers of the untrained group over the trained group negates its benefits.
文摘Ongoing climate change affects various aspects of an animal＇s life, with impor- tant effects on distribution range and phenology. The relationship between global warming and body size changes in mammals and birds has been widely studied, with most find- ings indicating a decline in body size over time. Nevertheless, little data exist on similar size change patterns of invertebrates in general and insects in particular, and it is unclear whether insects should decrease in size or not with climate warming. We measured over 4000 beetle specimens, belonging to 29 beetle species in 8 families, collected in Israel during the last 100 years. The sampled species are all herbivorous. We examined whether beetle body size had changed over the years, while also investigating the relationships between body size and annual temperature, precipitation, net primary productivity （NPP） at the collection site and collection month. None of the environmental variables, including the collection year, was correlated with the size of most of the studied beetle species, while there were strong interactions of all variables with species. Our results, though mostly neg- ative, suggest that the effect of climate change on insect body size is species-specific and by no means a general macro-ecological rule. They also suggest that the intrapopulation variance in body size of insects collected as adults in the field is large enough to conceal intersite environmental effects on body size, such as the effect of temperature and NPE
文摘Antlions and wormlions are distantly related insect taxa,both digging pits in loose soil and ambushing arthropod prey.Their hunting method,which is rare in the animal kingdom,is a clear example of convergent evolution.There is little research directly comparing the 2 pit-building taxa.Using the same experimental platform to investigate how they respond to biotic and abiotic environmental factors enables an examination of their convergence and its limits.We investigated the response of antlions and wormlions to 3 factors common in their daily life:disturbance to the pits,prey arrival,and conspecific competitors.Although both increased the pit size following disturbance,wormlions increased it faster than antlions.Antlions responded to prey faster than wormlions,but wormlions im-proved their response time over days.The most diverging response was toward conspecifics.Whereas antlions relocated their pits fast in response to increasing conspecific density,wormlions never relocated.We suggest expla-nations for the behavioral differences between the taxa.Our results imply that despite the similar hunting method of the 2 taxa they may differ greatly in their behavior,which in turn might have consequences for their habitat use and population dynamics.
基金We thank the German Research Foundation for funding this research project(DFGgrant no.FO 298/31-1).
文摘Theories of forgetting highlight 2 active mechanisms through which animals forget prior knowledge by recipro-cal disruption of memories.According to“proactive interference,”information learned previously interferes with the acquisition of new information,whereas“retroactive interference”suggests that newly gathered information interferes with already existing information.Our goal was to examine the possible effect of both mechanisms in the desert ant Cataglyphis niger,which does not use pheromone recruitment,when learning spatial information while searching for food in a maze.Our experiment indicated that neither proactive nor retroactive interference took place in this system although this awaits confirmation with individual-level learning assays.Rather,the ants’persistence or readiness to search for food grew with successive runs in the maze.Elevated persistence led to more ant workers arriving at the food when retested a day later,even if the maze was shifted between runs.We support thisfinding in a second experiment,where ant workers reached the food reward at the maze end in higher numbers after encountering food in the maze entry compared to a treatment,in which food was present only at the maze end.This result suggests that spatial learning and search persistence are 2 parallel behavioral mechanisms,both assisting foraging ants.We suggest that their relative contribution should depend on habitat complexity.
