Effects Of Predation Risks Of Bats On The Growth,Development,Reproduction,and Hormone Levels Of Spodoptera Litura

Predation is a powerful selective pressure that shapes predator-prey interactions.Predators can influence prey through both direct consumption effects and indirect predation-risk effects,thereby influencing their population dynamics,community composition and ecosystem function.Density interactions driven by predation consumption have received widespread attention and research,and the results have both underpinned the understanding of species interactions and community dynamics and contributed to the generation of most ecological theories related to predator-prey interactions.However,predation risk effects can also affect the population dynamics and fitness of prey by increasing the cost of prey counter-predation;therefore,predation risk effects have received increasing attention in recent years,and ecologists have found that the indirect effects of predation risk effects on prey are comparable to,or even greater than,the direct effects.Currently,studies of predation risk effects have focused on insects,amphibians,fish,birds,and diurnal mammals,while relatively little attention has been paid to nocturnal animals.Bats occupy a unique ecological niche in the night sky,and about 70% of bats are insectivorous.Long-term interactions between bats and moths have led moths to evolve auditory organs to perceive the echolocation calls of bats,which results in bats can exert predation risk effects on moths.However,the trait response and non-consumptive effects of bat predation risk on insects triggered by bats are sparsely studied relative to the direct predatory effects of bats on insects and their functions in the ecosystem.Therefore,in this study,the agricultural pest Spodoptera litura was used as a research object to integrate the theories and methods from ecology(growth and development monitoring),behavior(acoustic playback and behavioral observation)and physiology(hormone measurement)to investigate the effects of the CF type Chinese Horseshoe Bat(Rhinolophus sinicus)and the FM type Asian long-winged bat(Miniopterus fuliginosus)as predator risk to investigate the effects of bat predation risk on the growth and development,reproduction and hormone levels of S.litura.The main findings are as follows.1.When exposed to different bat predation risks the larvae of the S.litura were able to complete the entire generation,however increased larval food intake,accelerated the developmental of the larval stages;prolonged the pupal stage,had a lower pupal weight;increased mortality of larvae,decreased significantly the pupation rate and eclosion rate,indicating that the bat predation risks led to changes in the life history strategy of the S.litura,decreased fitness.2.When the S.litura were exposed to different predation risks,the frequency of adult activity,the proportion of times pent on moving,mating and courtship were significantly decreased;the egg production of adult and egg hatching rate decreased significantly,indicating that bat predation risks had a significant negative impact on the reproductive level of the S.litura.3.When the S.litura were exposed to different predation risks the juvenile hormone titers and 20-Ecdydysone hormone titers of the S.litura in the larval stage,pupal stage and adult males and females were significantly increased,and the increase of both hormones synergistically regulated the larval development.In addition,JH could promote reproductive function of S.litura,while 20-E could enhance immune function of S.litura.These results suggested a trade-off between growth and reproduction by altering hormone levels in the S.litura.Nevertheless,the S.litura still payed the price of high mortality,high metamorphosis failure,and decreased reproduction rates.4.There were differences in the negative effects of different bat predation risks on the oblique night moth.The overall effect was greatest in the FM-exp group,followed by the CF-exp group,the FM-call group,the CF-call group and the white noise group,indicating that the S.litura can perceive different predation risks and noises,and further respond to different degrees.In summary,our study suggested that the predation risk effects of bat lead to changes in the behavioral and physiological traits of the S.litura,which furthered leads to a reduction in growth and reproduction,and ultimately may have a significant negative impact on the population dynamics of the moth.This study shows the potential of bat predation risk to influence moth population dynamics,provides new insights into an effective biological control approach,and provides a theoretical basis for the realization of "bat ultrasound for pest control" and the conservation of bat diversity.