Reproductive Behavioral Tactics Of Sclerodermus Guani Xiao Et Wu(Hymenoptera:Bethylidae)

Sclerodermus guani Xiao et Wu(Hymenoptera:Bethylidae)is one of specialized parasitic wasps,which parasitize coleopteran,lepidopteran and other wood boring insects.It is one of effective natural enemies for controlling Cerambycidae,Buprestidae and bark beetles,.Numerous studies on S.guani have been carried out,most of which focus on biological characteristics,control applications and qualitative description of parasitism behavior.But few quantitative studies have been made on pre-oviposition time,and ovipositon behaviors associated with brood tending.Therefore,this thesis focuss on S.guani behavioral tactics by investigating maternal effects on offspring developmental performances.Results obtained from this study provide new data for the understanding of S.guani social behavior and helps with its mass-productionin biological control.1.Effects of maternal care and number of offspring larvae on developmental performances of offspring parasitoidsTo understand how maternal care and density of offspring density affect developmental performances of offspring parasitoids,two maternal care treatments(with and without tending)were imposed on the offspring larvae,which were manipulated as 10,20,30,40,and above 50 on a host larvae weighted,respectively.The results showed that maternal care did not significantly affect the survival rate of larvae to adults,but significantly increased larval mortality.Larval mortality rate increased with increasing number of larvae.Larval survival rate increased with increasing host body weight.The number of initial larvae and host body weight at parasitism did not affect sex ratio of offspring parasitoids.However,male proportion increased with host weight without the maternal care.Offspring female body size decreased with increasing number of larvae,but increased with increasinghost body weight.The results suggest that host body size and parasitoid larval laoad can have an overwriting influcne than brood tending on offspring development.2.Effects of host body size and number of foundresses on pre-oviposition time anddevelopmental durationSclerodermus parasitoids are unusual amongst parasitoids in that multiple females(foundresses)share a host,by not only attacking and ovipositing on a single host but together tending the developing brood.The foundresses can be under high selection pressure to effectively exploit resources on the host they share.Here we examined time-specific behavior of foundresses and developmental traits of offspring parasitoids in response to host body size and numbers of foundresses.We manipulated numbers of S.guani foundresses as 1,2,4,6 and 8,respectively,and then exposed to the foundresses for parasitism a long horned beetle(Monoohamus alternatus)larva,which varied continuously in body weight within a wide range.The pre-oviposition time of foundresses and the duration of successive life stages of offspring parasitoids were recorded.[Results]The pre-oviposition time increased in relation to increasing host body weight,but decreased in the presence of more foundresss in compared to the presence of fewer foundresses,decreasing by 17.5%,35.8%,41.3%,and 49.7%in the presence of 2,4,6,and 8 foundresses,respectively,compared to the presence of 1 foundress.The egg,larval,and pupal development duration did not vary in response to host body weight and numbers of foundresses,averaged out to 7.27,6.81,and 14.38 days,respectively.The results of this study suggest that Sclerodermus females can adjust their pre-oviposition time as an adaptive trait in response to host body size and number s of foundresses.3.Maximum fecundity and sex radio of Sclerodermus guaniTo explore the reproductive potential of S.guani,this study,using high quality long-horned beetle Saperda populnea larvae as the host,investigated daily ovipsoiton in clutch size and sex radio of S.gunai on single or multiple hosts in a lifetime.The results showed that the number of eggs laid was significantly affected by the number of hosts available-When supplied with new hosts daily,S.guani female deposited 184.5 ± 9.6(SD)eggs,which was higher than the parasitoid when supplied with single host in a life time 37.2 ± 1.2(SD)eggs.More adult parasitoids emerged from the multiple hosts treatment than from the single host treatment.Sex ratio was extremely biased to males,up to all maes,for females later in their life attacking multiple hosts.Egg hatching rate under the multiplehosts treatment decreased compared to that under the single host treatment,but larval survival and offspring body size increased under the former than later treatments.Oviposition days and host body weight were interacted in affecting number of female oviposition.The numder of eggs laid daily decreased with ovipostion days,but increased with host body size.The results of this study suggest that S.guani has potential to parasitize more than one host.