The Impact Of Pardosa Pseudoannulata To The Reproductive Behavior Of P.mionebulosa In The Sympatric Habitat

For a long time,people studying on the dynamic relationship between the predator-predator research has mainly focused on the competition of resources and space,and between the reproductive dynamics,especially how the predator affect the predator reproductive status is often ignored,especially in sympatric habitat,with highly overlapping niche between predator and predator.Spiders are characterized by large predation,wide feeding ability and strong reproduction.They are important natural predators in agricultural ecosystem,which can effectively control the number of pests,play a very important role in the prevention and control of pests,and have great potential of biocontrol in the farmland ecosystem.Wolf spider is a very large predator in rice fields in the middle and lower reaches of the Yangtze River,and there are many species.While controlling pests,different species can also prey on each other.Therefore,understanding their interactions is of overall significance for the comprehensive use of different populations of wolf spiders for biological control in the field.In this project,we used two species of wolf spiders that living in the sympatric habitat with almost the same niche,Pardosa pseudoannulata and P.mionebulosa,to study the the effects of the visual and olfactory signals of predator on the reproduction of the prey.The experiment is divided into two parts:(1)Effects of visual signals in of P.pseudoannulata to the reproduction of P.mionebulosa.We designed experiments for mating and reproduction of P.mionebulosa in the presence of P.pseudoannulata,in which P.mionebulosa can clearly see the existence of predator P.pseudoannulata.The results showed that,compared with the absence of the spider,the exploration time of the male spider was significantly increased,the courtship time was significantly increased,the mating success rate was significantly decreased,but the number of spiders female produced was significantly decreased.This result shows that the predator P.pseudoannulata has a strong "stress" effect on the prey P.mionebulosa,and P.mionebulosa has a significant change in behavior.In addition,as can be seen from the reflection spectrum of the bodies of the two species,the reflectivity of P.mionebulosa is higher,which indicates that P.pseudoannulata is more crypsis in body color than the prey P.mionebulosa,and is more conducive to its predation.This may be an adaptive feature of P.pseudoannulata spider that formed during the coevolution.(2)Effects of olfactory signals of P.pseudoannulata on the reproduction of P.mionebulosa.We designed experiments to allow P.mionebulosa to mate and reproduce if they could "smell" but see the spider.Similar to the results of the visual signal experiment,compared with no P.pseudoannulata spider odor presence,when P.mionebulosa spider can feel P.pseudoannulata spider odor,male exploration time significantly increased,courtship duration also significantly extended,but the mating success rate significantly reduced,and the number of female spider mating spiders also significantly reduced.It shows that the odor material of the predator can also give prey a strong "stress" effect from the sense of smell,so that the behavior of the P.mionebulosa changes.Through the Y-type olfactometer choice experiment,we confirmed that P.mionebulosa could indeed feel the odor material released by P.pseudoannulata.In addition,by electrophysiological reaction and gas chromatography,we identified two compounds heptacosane and 2,6,10-trimethyltetradecane,from the cuticle of P.pseudoannulata that can induce reaction P.mionebulosa.This shows that P.mionebulosa has evolved the ability to "eavesdrop" on the chemical signal material from the sympatric predator P.pseudoannulata.(3)Effect of the coexistence of visual and olfactory signals of P.pseudoannulata on the reproduction of P.mionebulosa.Pardosa mionebulosa was allowed to mate and reproduce under the presence of both visual and olfactory signals of P.pseudoannulata in the laboratory.The result showed that comparing with the situation that both visual and olfactory signals of P.pseduannulata were absent,when Pardosa mionebulosa can feel the existence of both visual and olfactory signals,the male exploration time significantly increased,courtship duration also significantly extended,but the mating success rate significantly reduced,and the number of female spider mating spiders also significantly reduced.In addition,it seems that the impact was higher that that when either the visual signal of olfactory signal existed alone.In conclusion,this study demonstrates for the first time that P.mionebulosa evolved the ability to judge odor of predator P.pseudoannulata under strong predatory pressure.This is also the first time to show that predators in the sympatric habitat with the same niche can produce reproductive stress on the prey.However,it is necessary to verify how P.mionebulosa dealing with this stress in the field environment.