Preliminary Study On Selectivity And Host-adaption Mechanism Of Batocera Horsfieldi To Juglans Regia L And Eucalyptus Spp

Batocera horsfieldi is a major polyphagous wood-boring beetle.A large number of domestic and foreign scholars have focused on the way of its biological characteristics,controlling measures,host interactions,et al in recent years,but they have not yet described the selectivity and the host-selection mechanisms of it to Juglans regia L.and Eucalyptus spp.In this study,the populations of B.horsfieldi of J.regia and Eucalyptus were used as research objects.The selection behavioral responses of B.horsfieldis to them were studied by exchanging the host.Its adaptation mechanisms to J.regia or Eucalyptus were explored by the changes of enzyme activities in the body after the larvae were fed J.regia or Eucalyptus.The research results are as follows:1.Tropism of the adults of B.horsfieldi in the population of J.regia to volatile matters from the bark,leaf,twig of J.regia was significantly higher than that in the corresponding organs of Eucalyptus.In the nutritional replenishment period,there was no significant difference in the tropism rate of adults toward bark,leaf or twig of J.regia.The tropism rate of female adults to bark volatiles after mating was significantly higher than that of male adults after mating,but there was no significant difference between the genders in the tropism rate of adults to twig or leaf volatiles of J.regia after mating.2.Whether the adult was mating or not,there had no significant difference on the tropism rate of twig or leaf volatiles of J.regia.But the tropism rates of male unmated adults and female mated adults to the bark volatiles of J.regia were significantly higher than those of male mated adults and female unmated adults respectively.3.Adults of B.horsfieldi in the population of J.regia have EAG responses to the volatiles of the three organs of the bark,twig and leaf of J.regia and Eucalyptus.The response value of EAG to volatiles in the bark of J.regia of female adults was significantly higher than that of male adults,but there was no significant difference in the EAG response value to volatiles in other organs between the genders.4.The EAG response value of male unmated adults to the volatiles of twig of J.regia was significantly lower than that of Eucalyptus,but there was no significant difference between the volatiles of other organs whether the male adult was mating or not.There was no significant difference on the EAG response values between unmated and mated females to the volatiles of leaf of J.regia,but there was significant difference on the EAG response values of volatiles of other organs between unmated and mated female adults.5.Under the selective trial conditions,the adults of B.horsfieldi in the population of J.regia tended to choose J.regia to feed or oviposit,while in the case of forced feeding the bark of Eucalyptus,their feeding intake decreased and they did not oviposit in Eucalyptus.The feeding tendency of larvae is similar to that of adults,but forcing larvae to feed on new host can reduce the feeding tropism rate of larvae to the original host.6.The content of nutrient substances in the leaf,bark and twig of J.regia was significantly higher than that in the corresponding organs of Eucalyptus,while the content of secondary substances was significantly lower than that in the corresponding organs of Eucalyptus.7.The activities of digestive enzymes,detoxifying enzymes and protective enzymes in larvae of different hosts were significantly different.Host switching had significant effects on the activities of digestive enzymes,detoxifying enzymes and protective enzymes in larvae of B.horsfieldi.Among them,Ach E increased significantly,while tryptase,Endoglucanase,PPO,GSTs and SOD decreased significantly.Conclusions: Batocera horsfieldi has a preference for different hosts.The population of J.regia and Eucalyptus have the mechanism of switching hosts and adapting to new hosts.