Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a b...Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.展开更多
In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle a...In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle and top predators and logistic grow for the (common) prey. The existence of such limit cycle is guaranteed, via the first Lyapunov coefficient and the Andronov-Hopf bifurcation theorem, under certain conditions for the parameters involved in the system.展开更多
Based on the niche theory,a class of delayed intraguild predation systems integrating Holling type I and type II functional response functions is constructed.Firstly,the existence conditions of the positive equilibriu...Based on the niche theory,a class of delayed intraguild predation systems integrating Holling type I and type II functional response functions is constructed.Firstly,the existence conditions of the positive equilibrium point of the system are clarified.Secondly,the dynamic behavior of the system is analyzed from two aspects:in the absence of time delay,the local stability of the positive equilibrium point of the system is analyzed by using the Hurwitz criterion.In the presence of time delay,with the gestation delay of the predator population as the bifurcation parameter,the existence of Hopf bifurcation near the positive equilibrium point of the system is explored,and the properties of Hopf bifurcation are analyzed by means of the center manifold theorem and normal form theory.Finally,the correctness of the theoretical derivation is verified by numerical simulation.展开更多
This study was carried out on the ability of predatory thrips Scolothrips longi- cornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus （McGregor） on ...This study was carried out on the ability of predatory thrips Scolothrips longi- cornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus （McGregor） on Typhlodromus bagdasarjani Wainstein and Aru- tunjan and vice versa was evaluated. The larvae, prepupae, and pupae of thrips and the eggs, larvae, and protonymphs of phytoseiids were selected as intraguild prey. The in- traguild predation （IGP） among S. longicornis and 2 phytoseiid species was unidirectional and in favor of phytoseiids, i.e., S. longicornis was not able to feed on larval stages of 2 phytoseiids. However, N. californicus and T. bagdasarjani fed on the 1st instar larvae （1.39 and 0.80 per day）, 2nd instar larvae （0.87 and 0.55 per day）, prepupae （0.51 and 0.48 per day）, and pupae of thrips （0.51 and 0.49 per day, respectively）. Both phytoseiids fed on eggs, larvae, and protonymphal stages of each other. Females of N. californicus con- sumed more phytoseiid larvae （2.49 per day） than T. bagdasarjani, which consumed 1.08 N. californicus larvae per day. When Tetranychus urticae was presented as an extraguild prey, intensity oflGP between 2 species ofphytoseiids and on larval stages ofS. longicornis reduced significantly. Therefore, it is concluded that （i） IGP existed among the 3 examined species and lack of feeding of S. longicornis on 2 phytoseiid species can be justified by its feeding type （monophagy）, （ii） N. californicus was much more prone to IGP than was T. bagdasarjani.展开更多
Zoophytophagous mirid species,that feed and develop either on prey or plant resources,are often found simultaneously on the same host.Hence,these species can engage in both intraguild predation and cannibalism,which c...Zoophytophagous mirid species,that feed and develop either on prey or plant resources,are often found simultaneously on the same host.Hence,these species can engage in both intraguild predation and cannibalism,which can pose a threat to mirid eggs.Ovipositing females may respond to such risks of predation on their eggs by reducing the number of eggs laid or selecting safer oviposition sites.We tested the oviposition behavior of Macrolophus pygmaeus(Rambur)(Hemiptera:Miridae)females under the risk of cannibalism by M.pygmaeus males and intraguild predation by Nesidiocoris tenuis(Reuter)males(Hemiptera:Miridae)under laboratory conditions.Intraguild predators and cannibals were introduced during or after the oviposition period.The number of eggs laid(using counts of newly hatched nymphs)and their proportion on each part of a tomato plant were both measured.The results reveal that only cannibalism by M.pygmaeus males after the period of oviposition significantly decreased the number of hatched eggs.Cannibalism thus represents a greater risk to mirid eggs than intraguild predation.The M.pygmaeus female responded to the presence of potential intraguild predators(or competitors)by decreasing the nu mber of eggs laid in the upper leaves.The results suggest that M.pygmaeus females avoid competition by N.tenuis,by laying fewer eggs on upper leaves.Cannibalism could regulate zoophytophagous predator populations under prey scarcity conditions and minimize the risk of crop damage associated with those biological control agents.展开更多
The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermedia...The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermediate predator and top predator. First,the model without self-limitation of the predators is studied. Boundedness of the systemand existence of non-negative solutions are established. The local stability analysisof the equilibria is carried out to examine the behavior of the system. The possibilityof Hopf bifurcation around non-negative equilibria with consumption rates as bifurcationparameters is studied. Center manifold theorem and the normal form theory areapplied to obtain the formulas for determining the direction of Hopf bifurcation and thestability of bifurcating periodic solutions. Numerical simulations support the analyticalfindings, which show that the extinction of one of the predators can occur under certainrestrictions on the predation rate of the top predator. Subsequently, numerical analysisof the model with self-limitation of the predators is carried out. Simulations reveal thatthe system with intraspecific competition in the predator populations can reproducecoexistence between the three species in resource-rich environment.展开更多
The aim of this work is to investigate the existence and non-existence of traveling wave solutions for a diffusive three-species intraguild predation model which means that one predator can eat its potential resource ...The aim of this work is to investigate the existence and non-existence of traveling wave solutions for a diffusive three-species intraguild predation model which means that one predator can eat its potential resource competitors. The method of upper-lower solution is implemented to show the existence of traveling wave solutions. In order to simplify the construction of an admissible pair of upper lower solution, the scheme of strictly con- tracting rectangle is applied. Finally, the minimal speed c＊ of traveling wave solutions of the model is characterized. If the wave speed is greater than c＊, we show the exis- tence of traveling wave solutions connecting trivial and positive equilibria by combining the upper and lower solutions with the contracting rectangle. On the other hand, if the wave speed is less than c＊, the non-existence of such solutions is also established. Furthermore, to illustrate our theoretical results, some numerical simulations are performed and biological meanings are interpreted.展开更多
Direct treatment of predators with entomopathogenic fungi (EPF) at different concentrations revealed that some species, like <i>Beauveria bassiana</i> and <i>Metarhizium anisopliae</i>, were fo...Direct treatment of predators with entomopathogenic fungi (EPF) at different concentrations revealed that some species, like <i>Beauveria bassiana</i> and <i>Metarhizium anisopliae</i>, were found to have detrimental effects on all developmental stages of some predator species. Other species, like <i>Numoraea rileyi</i> and <i>Paecilomycis fumosorosius</i>, showed little or no effect on treated predators. Adult predators were found to avoid feeding on fungi-infected prey. EPF could be isolated from hibernating or field-collected coccinellids. Some studies indicated that combining a fungus with a predator could increase the rate of insect control in the field. As for parasitoids, this review indicates that the developmental stages of the egg parasitoids can develop successfully in host eggs treated with fungi. However, fungus-infected hosts negatively impact the development of larval parasitoids inside such hosts and this impact depends on the species and concentration of the fungus as well as the time between infection and parasitism. Some parasitoid females can discriminate between fungus-infected and uninfected hosts and do not parasitize the infected hosts. With appropriate timing, the parasitoids or predators could be combined with fungi for the biological control of insects in the field.展开更多
基金Supported by the National Key Research and Development Program of China(No.2017YFC1404405)the Taishan Scholar Climbing Plan to Sun Song,the Shandong Joint Fund for Marine Ecology and Environmental Sciences(No.U1606404)the Aoshan Science and Technology Innovation Project(No.2016ASKJ02-2)。
文摘Jellyfish blooms occur worldwide and have resulted in serious problems in tourism,fisheries,coastal industries,and the marine ecosystem.The life cycle of scyphozoan jellyfish consists of a pelagic medusa stage and a benthic polyp stage.Success of asexual reproduction of the polyps determines directly the number of medusae;thus,the polyp stage is the key to understanding the population dynamics of medusae.Nemopilema nomurai,Aurelia coerulea,and Rhopilema esculentum are three scyphozoan jellyfish commonly inhabit in Chinese coastal waters.Polyps of A.coerulea are easily visible,while those of N.nomurai and R.esculentum remain yet to be found in the wild.However,distribution of the medusa indicates that the polyps of all three species may occur together.To evaluate the distribution pattern of polyps of the three species and explore intraguild predation by the polyps,we conducted a laboratory experiment that considered the attachment sequence and size relationship of calyx diameter of the polyps.We found that the polyps of A.coerulea preyed on polyps of the other two species in all treatments,except when polyps of R.esculentum were bigger than those of A.coerulea.The polyps of R.esculentum preyed on the polyps of N.nomurai only when polyps of R.esculentum attached first and were bigger than those of N.nomurai.Colonies of N.nomurai polyps were rarely found in the places inhabited by A.coerulea polyps.In addition,A.coerulea polyps are known to inhabit at depths of less than 20 m in coastal sea,thus,we speculate that N.nomurai polyp colonies might occur at depths of more than 20 m.Therefore,our finding that polyps of A.coerulea aggressively preyed on polyps of other species may help understand other such systems of jellyfish bloom in the world.
文摘In this paper, we prove the existence of a limit cycle for a given system of differential equations corresponding to an asymmetrical intraguild food web model with functional responses Holling type II for the middle and top predators and logistic grow for the (common) prey. The existence of such limit cycle is guaranteed, via the first Lyapunov coefficient and the Andronov-Hopf bifurcation theorem, under certain conditions for the parameters involved in the system.
文摘Based on the niche theory,a class of delayed intraguild predation systems integrating Holling type I and type II functional response functions is constructed.Firstly,the existence conditions of the positive equilibrium point of the system are clarified.Secondly,the dynamic behavior of the system is analyzed from two aspects:in the absence of time delay,the local stability of the positive equilibrium point of the system is analyzed by using the Hurwitz criterion.In the presence of time delay,with the gestation delay of the predator population as the bifurcation parameter,the existence of Hopf bifurcation near the positive equilibrium point of the system is explored,and the properties of Hopf bifurcation are analyzed by means of the center manifold theorem and normal form theory.Finally,the correctness of the theoretical derivation is verified by numerical simulation.
文摘This study was carried out on the ability of predatory thrips Scolothrips longi- cornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus （McGregor） on Typhlodromus bagdasarjani Wainstein and Aru- tunjan and vice versa was evaluated. The larvae, prepupae, and pupae of thrips and the eggs, larvae, and protonymphs of phytoseiids were selected as intraguild prey. The in- traguild predation （IGP） among S. longicornis and 2 phytoseiid species was unidirectional and in favor of phytoseiids, i.e., S. longicornis was not able to feed on larval stages of 2 phytoseiids. However, N. californicus and T. bagdasarjani fed on the 1st instar larvae （1.39 and 0.80 per day）, 2nd instar larvae （0.87 and 0.55 per day）, prepupae （0.51 and 0.48 per day）, and pupae of thrips （0.51 and 0.49 per day, respectively）. Both phytoseiids fed on eggs, larvae, and protonymphal stages of each other. Females of N. californicus con- sumed more phytoseiid larvae （2.49 per day） than T. bagdasarjani, which consumed 1.08 N. californicus larvae per day. When Tetranychus urticae was presented as an extraguild prey, intensity oflGP between 2 species ofphytoseiids and on larval stages ofS. longicornis reduced significantly. Therefore, it is concluded that （i） IGP existed among the 3 examined species and lack of feeding of S. longicornis on 2 phytoseiid species can be justified by its feeding type （monophagy）, （ii） N. californicus was much more prone to IGP than was T. bagdasarjani.
基金the Spanish Ministry of Economy and Competitiveness(Project AGL2011-24349)the CERCA Programme of the Generalitat de Catalunya.
文摘Zoophytophagous mirid species,that feed and develop either on prey or plant resources,are often found simultaneously on the same host.Hence,these species can engage in both intraguild predation and cannibalism,which can pose a threat to mirid eggs.Ovipositing females may respond to such risks of predation on their eggs by reducing the number of eggs laid or selecting safer oviposition sites.We tested the oviposition behavior of Macrolophus pygmaeus(Rambur)(Hemiptera:Miridae)females under the risk of cannibalism by M.pygmaeus males and intraguild predation by Nesidiocoris tenuis(Reuter)males(Hemiptera:Miridae)under laboratory conditions.Intraguild predators and cannibals were introduced during or after the oviposition period.The number of eggs laid(using counts of newly hatched nymphs)and their proportion on each part of a tomato plant were both measured.The results reveal that only cannibalism by M.pygmaeus males after the period of oviposition significantly decreased the number of hatched eggs.Cannibalism thus represents a greater risk to mirid eggs than intraguild predation.The M.pygmaeus female responded to the presence of potential intraguild predators(or competitors)by decreasing the nu mber of eggs laid in the upper leaves.The results suggest that M.pygmaeus females avoid competition by N.tenuis,by laying fewer eggs on upper leaves.Cannibalism could regulate zoophytophagous predator populations under prey scarcity conditions and minimize the risk of crop damage associated with those biological control agents.
文摘The dynamics of a three-component model for food web with intraguild predation isconsidered. The model is based on the collection of ordinary differential equations thatdescribe the interactions among prey, intermediate predator and top predator. First,the model without self-limitation of the predators is studied. Boundedness of the systemand existence of non-negative solutions are established. The local stability analysisof the equilibria is carried out to examine the behavior of the system. The possibilityof Hopf bifurcation around non-negative equilibria with consumption rates as bifurcationparameters is studied. Center manifold theorem and the normal form theory areapplied to obtain the formulas for determining the direction of Hopf bifurcation and thestability of bifurcating periodic solutions. Numerical simulations support the analyticalfindings, which show that the extinction of one of the predators can occur under certainrestrictions on the predation rate of the top predator. Subsequently, numerical analysisof the model with self-limitation of the predators is carried out. Simulations reveal thatthe system with intraspecific competition in the predator populations can reproducecoexistence between the three species in resource-rich environment.
文摘The aim of this work is to investigate the existence and non-existence of traveling wave solutions for a diffusive three-species intraguild predation model which means that one predator can eat its potential resource competitors. The method of upper-lower solution is implemented to show the existence of traveling wave solutions. In order to simplify the construction of an admissible pair of upper lower solution, the scheme of strictly con- tracting rectangle is applied. Finally, the minimal speed c＊ of traveling wave solutions of the model is characterized. If the wave speed is greater than c＊, we show the exis- tence of traveling wave solutions connecting trivial and positive equilibria by combining the upper and lower solutions with the contracting rectangle. On the other hand, if the wave speed is less than c＊, the non-existence of such solutions is also established. Furthermore, to illustrate our theoretical results, some numerical simulations are performed and biological meanings are interpreted.
文摘Direct treatment of predators with entomopathogenic fungi (EPF) at different concentrations revealed that some species, like <i>Beauveria bassiana</i> and <i>Metarhizium anisopliae</i>, were found to have detrimental effects on all developmental stages of some predator species. Other species, like <i>Numoraea rileyi</i> and <i>Paecilomycis fumosorosius</i>, showed little or no effect on treated predators. Adult predators were found to avoid feeding on fungi-infected prey. EPF could be isolated from hibernating or field-collected coccinellids. Some studies indicated that combining a fungus with a predator could increase the rate of insect control in the field. As for parasitoids, this review indicates that the developmental stages of the egg parasitoids can develop successfully in host eggs treated with fungi. However, fungus-infected hosts negatively impact the development of larval parasitoids inside such hosts and this impact depends on the species and concentration of the fungus as well as the time between infection and parasitism. Some parasitoid females can discriminate between fungus-infected and uninfected hosts and do not parasitize the infected hosts. With appropriate timing, the parasitoids or predators could be combined with fungi for the biological control of insects in the field.
