Encapsulation is a nonspecific, cellular response through which insects defend themselves against multicellular pathogens. During this immune reaction, haemocytes recognize an object as foreign and cause other haemocy...Encapsulation is a nonspecific, cellular response through which insects defend themselves against multicellular pathogens. During this immune reaction, haemocytes recognize an object as foreign and cause other haemocytes to aggregate and form a capsule around the object, often consisting of melanized cells. The process of melanisation is accompanied by the forma- tion of potentially toxic reactive oxygen species, which can kill not only pathogens but also host cells. In this study we tested whether the encapsulation response is costly in mealworm beetles Tenebrio molitor. We found a negative relationship between the duration of implantation via a nylon monofilament and remaining life span. We also found a negative relationship between the strength of immune response and remaining life span, suggesting that cellular immunity is costly in T. molitor, and that there is a trade-off between immune response and remaining life span. However, this relationship disappeared at 31-32 hours of implanta- tion at 25 ± 2℃. As the disappearance of a relationship between duration of implantation and lifespan coincided with the highest values of encapsulation response, we concluded that the beetles stopped investment in the production of melanotic cells, as the implant, a synthetic parasite, was fully isolated from the host＇s tissues .展开更多
Background:The abundance of insects has decreased considerably during recent decades,resulting in current abundance showing 70-80%reductions in more than 15 studies across temperate climate zones.Dramatic reduc-tions ...Background:The abundance of insects has decreased considerably during recent decades,resulting in current abundance showing 70-80%reductions in more than 15 studies across temperate climate zones.Dramatic reduc-tions in the abundance of insects are likely to have consequences for other taxa at higher trophic levels such as preda-tors and parasites.Pesticides,fertilizers and agricultural land use are likely candidates accounting for such reductions in the abundance of insects.Methods:Here we surveyed the abundance of flying insects,and the reduction in the abundance of insects as a consequence of intensive reduction in agricultural practice linked to fertilizer use and pesticide use.Finally we dem-onstrated consistency in abundance of birds among study sites.Results:We demonstrated that the use of fertilizers and pesticides had reduced the abundance of insects,with consequences for the abundance of insectivorous bird species such as Barn Swallows(Hirundo rustica),House Martins(Delichon urbicum)and Swifts(Apus apus).Juvenile Barn Swallows were negatively affected by the reduced abundance of insects and hence the reproductive success of insectivorous bird species.These effects imply that the abundance of insects could be reduced by the availability of insect food.Conclusions:These effects of intensive agriculture on insect food abundance are likely to have negative impacts on populations of insects and their avian predators.This hypothesis was validated by a reduction in the abundance of insects,linked to an increase in the abundance of fertilizers and a general change in farming practice.展开更多
The resources available to an individual in any given environment are finite, and variation in life history traits reflect differential allocation of these resources to competing life functions. Nutritional quality of...The resources available to an individual in any given environment are finite, and variation in life history traits reflect differential allocation of these resources to competing life functions. Nutritional quality of food is of particular importance in these life history decisions. In this study, we tested trade-offs among growth, immunity and survival in 3 groups of greater wax moth （Galleria mellonella） larvae fed on diets of high and average nutritional quality. We found rapid growth and weak immunity （as measured by encapsulation response） in the larvae of the high-energy food group. It took longer to develop on food of average nutritional quality. However, encapsulation response was stronger in this group. The larvae grew longer in the low-energy food group, and had the strongest encapsulation response. We observed the highest survival rates in larvae of the low-energy food group, while the highest mortality rates were observed in the high-energy food group. A significant negative correlation between body mass and the strength of encapsulation response was found only in the high-energy food group revealing significant competition between growth and immunity only at the highest rates of growth. The results of this study help to establish relationships between types of food, its nutritional value and life history traits of G. mellonella larvae.展开更多
Immune defenses of insects show either broad reactions or specificity and durability of induced protection against attacking parasites and pathogens. In this study, we tested whether encapsulation response against nyl...Immune defenses of insects show either broad reactions or specificity and durability of induced protection against attacking parasites and pathogens. In this study, we tested whether encapsulation response against nylon monofilament increases between two attempts of activation of immune system in mealworm beetles Tenebrio molitor, and whether previous exposure to nylon monofilament may also increase protection against an entomopathogenic fungus. We found that survival of beetles subjected to immune activation by nylon implant and subsequent fungal exposure a week later was significantly higher than survival of beetles which had been subjected to fimgal infection only. This result suggests that previous immune activation by the nylon implant may be considered as broad spectrum ＂immune priming＂ which helps to fight not only the same intruder but also other parasites.展开更多
文摘Encapsulation is a nonspecific, cellular response through which insects defend themselves against multicellular pathogens. During this immune reaction, haemocytes recognize an object as foreign and cause other haemocytes to aggregate and form a capsule around the object, often consisting of melanized cells. The process of melanisation is accompanied by the forma- tion of potentially toxic reactive oxygen species, which can kill not only pathogens but also host cells. In this study we tested whether the encapsulation response is costly in mealworm beetles Tenebrio molitor. We found a negative relationship between the duration of implantation via a nylon monofilament and remaining life span. We also found a negative relationship between the strength of immune response and remaining life span, suggesting that cellular immunity is costly in T. molitor, and that there is a trade-off between immune response and remaining life span. However, this relationship disappeared at 31-32 hours of implanta- tion at 25 ± 2℃. As the disappearance of a relationship between duration of implantation and lifespan coincided with the highest values of encapsulation response, we concluded that the beetles stopped investment in the production of melanotic cells, as the implant, a synthetic parasite, was fully isolated from the host＇s tissues .
基金supported by the Latvian Council of Science (grants lzp-2018/2-00057 and lzp-2020/2-0271)supported by the National Natural Science Foundation of China (Grant Nos. 31772453 and 31970427)
文摘Background:The abundance of insects has decreased considerably during recent decades,resulting in current abundance showing 70-80%reductions in more than 15 studies across temperate climate zones.Dramatic reduc-tions in the abundance of insects are likely to have consequences for other taxa at higher trophic levels such as preda-tors and parasites.Pesticides,fertilizers and agricultural land use are likely candidates accounting for such reductions in the abundance of insects.Methods:Here we surveyed the abundance of flying insects,and the reduction in the abundance of insects as a consequence of intensive reduction in agricultural practice linked to fertilizer use and pesticide use.Finally we dem-onstrated consistency in abundance of birds among study sites.Results:We demonstrated that the use of fertilizers and pesticides had reduced the abundance of insects,with consequences for the abundance of insectivorous bird species such as Barn Swallows(Hirundo rustica),House Martins(Delichon urbicum)and Swifts(Apus apus).Juvenile Barn Swallows were negatively affected by the reduced abundance of insects and hence the reproductive success of insectivorous bird species.These effects imply that the abundance of insects could be reduced by the availability of insect food.Conclusions:These effects of intensive agriculture on insect food abundance are likely to have negative impacts on populations of insects and their avian predators.This hypothesis was validated by a reduction in the abundance of insects,linked to an increase in the abundance of fertilizers and a general change in farming practice.
文摘The resources available to an individual in any given environment are finite, and variation in life history traits reflect differential allocation of these resources to competing life functions. Nutritional quality of food is of particular importance in these life history decisions. In this study, we tested trade-offs among growth, immunity and survival in 3 groups of greater wax moth （Galleria mellonella） larvae fed on diets of high and average nutritional quality. We found rapid growth and weak immunity （as measured by encapsulation response） in the larvae of the high-energy food group. It took longer to develop on food of average nutritional quality. However, encapsulation response was stronger in this group. The larvae grew longer in the low-energy food group, and had the strongest encapsulation response. We observed the highest survival rates in larvae of the low-energy food group, while the highest mortality rates were observed in the high-energy food group. A significant negative correlation between body mass and the strength of encapsulation response was found only in the high-energy food group revealing significant competition between growth and immunity only at the highest rates of growth. The results of this study help to establish relationships between types of food, its nutritional value and life history traits of G. mellonella larvae.
文摘Immune defenses of insects show either broad reactions or specificity and durability of induced protection against attacking parasites and pathogens. In this study, we tested whether encapsulation response against nylon monofilament increases between two attempts of activation of immune system in mealworm beetles Tenebrio molitor, and whether previous exposure to nylon monofilament may also increase protection against an entomopathogenic fungus. We found that survival of beetles subjected to immune activation by nylon implant and subsequent fungal exposure a week later was significantly higher than survival of beetles which had been subjected to fimgal infection only. This result suggests that previous immune activation by the nylon implant may be considered as broad spectrum ＂immune priming＂ which helps to fight not only the same intruder but also other parasites.
