The fecal shield is a double-edged sword for larvae of a leaf beetle

Larvae of some leaf beetles carry masses of feces covering parts or all of the body,which is called a"fecal shield'In general,the shield is thought to be a defense structure against natural enemies.However,some studies have suggested that defense effectiveness varies depending on the natural enemy.In this study,we used a fecal retention leaf beetle Ophrida xanthospilota(Coleoptera:Chrysomelidae),and 2 local generalist predators(an ant,Camponotus japonicus(Hymenoptera:Formicidae)and a stinkbug,Arma custos(Hemiptera:Pentatomidael)as a system to test the hypothesis that the fecal shield of O.xanthospilota plays different roles in predation behavior of different predators and can provide multiple chemical communication signals in predator-prey interactions.Prey bioassays showed that the fecal shield of O.xanthospilota larvae repelled the ant C.japonicus while attracting the stinkbug A.custos.The results also strongly demonstrated that hexane extracts of the fecal shield significantly repelled C.japonicus,while dichloromethane(DCM)extracts did not inhibit ant predation.Interestingly,DCM extracts attracted A.custos,but hexane extracts did not.Therefore,we suggest that the fecal shield is a double-edged sword for the larvae of O.xanthospilota.Our results also indicated that the risk-benefit tradeoff of an insect should be estimated at a community level involving multiple enemies(predators and parasites)and herbivores,rather than in a single prey-predator pair.

Climate shapes the spatiotemporal variation in color morph diversity and composition across the distribution range of Chrysomela lapponica leaf beetle

Color polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments.We explored the color morph diversity and composition in a Chrysomela lapponica leaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species.We obtained information on 13617 specimens of this beetle from museums,private collections,and websites.These specimens(collected from 1830-2020)originated from 959 localities spanning 33°latitude,178°longitude,and 4200 m altitude.We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism(quantified by the Shannon diversity index)and in the relative frequencies of individual color morphs.The highest level of polymorphism was found at high latitudes and altitudes.The color morphs differed in their climatic requirements;composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year,longitude,mean July temperature and betweenyear temperature fluctuations.The proportion of melanic beetles,in line with the thermal melanism hypothesis,increased with increasing latitude and altitude and decreased with increasing climate seasonality.Melanic morph frequencies also declined during the past century,but only at high latitudes and altitudes where recent climate warming was especially strong.The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments,presumably due to the different climatic requirements of coexisting color morphs.