| Panonychus citri,which is an agricultural pest that is widely distributed worldwide and causes serious damage to citrus.At present,chemical control measures are still mainly used in production which leading to the “3R” problem increasingly prominent.Neoseiulus californicus has the characteristics of strong adaptability,high predation,drought tolerance and high temperature resistance as the natural enemies of P.citri.Not only it records of field operations abroad but also collected in Sichuan and Guangdong areas of China.For the purpose of N.californicus can play a better role to P.citri in biological control,this article mainly studied the relationship among Citrus,P.citri and N.californicus and the results are as follows:1.Experiments on the attracting effect of P.citri to N.californicus shows: different period of P.citri have different attracting effects.Among P.citri with intact web-nest,P.citri female adults,P.citri nymph and P.citri larvae were all found had significantly attraction response to the predatory mite N.californicus.But,P.citri eggs and excreta both had no attraction response to the predatory mite.This attraction suggests that the N.californicus can be used for biological control of P.citri because of it’s good automatic search ability and control ability.2.The ambulatory dispersal experiments about N.californicus shows: The crawling diffusion rate of N.californicus is positively correlated with the prey density in its original habitat.The time of its diffusion and migration will increase with the increase of the prey density.When the eggs density of P.citri in the original leaf was 40,the time of the severe damage to the leaf under the different treatments was significantly higher than that when the egg density was 5 in the same situation.The diffusion time of N.californicus is also closely related to its own population density.The diffusion time of five predators pupae under the same experimental conditions was significantly shorter than that of one predator pupae.The spread time of N.californicus is also closely related to it’s feeding experience.Predator mites in a state of starvation will rapidly prey,and the number of prey will decline rapidly to speed up the rate of predation.When there are enough prey in the original habitat,the full predation process will significantly prolong its stay in the original leaf environment and the higher the prey density is,the more obvious this phenomenon is.However,there was no significant difference between N.californicus females adults and N.californicus nymph in the diffusion rate.During the experiment,the diffusion time of predatory mites was positively related to their predation.3.The olfactometer test and its component analysis of citrus leaf volatiles to the N.californicus shows: Using the self-made "Y" olfactory instrument to test the effects of five different treatments on the behavioral responses of N.californicus.The five different treatments are infested vane,healthy vane,infested vane without mites,mites and artificia damaged vane.Compare the 5 volatiles and clean air,infested vane and artificia damaged vane appeared extremely attractive,the selection rates were 76.67% and 66.67% respectively.There was a significant effect of attracting infested vane without mites with air and its selectivity was 61.67%.But,there was no obvious attraction of healthy vane and mites with clean air,and its selectivity was 46.67% and 56.67%.When the five kinds of treatments are compared with each other,infested vane selection rate was higher than the other four treatments and the healthy vane selection rate was lower than the other four treatments.The headspace sampling of the 5 treated volatiles was analyzed by GC/MS for composition and content analysis:Cyclohexene and 3-Carene only appear in infested vane.Bicyclo only appears in healthy vane.1,2-Benzenedicarboxylic acid,Bis(2-ethylhexyl)phthalate,1,5-Cyclooctadiene,2-(dodecyloxy)-only appear in infested vane without mites.Styrene only appears in mites.2,6,10,14,18,22-Tetracosahexaene,-1,3,6-Octatriene,3,7-dimethyl-,(Z)-,Cyclohexene,Tetratetracontane,Phthalic acid only appear in artificia damaged vane.However in this experiment,a large number of olefins were found in the leaves of the hazard treatment such as beta.-Myrcene,D-Limonene,Cyclohexene,1R-.alpha.-Pinene,Bicyclo,3-Carene,1-Docosene and Camphene.Cyclohexene and 3-Carene only appear in infested vane which may be volatiles produced by plants after being eaten by insects.4.The effect of N.californicus on control of P.citri on citrus seedlings shows: N.californicus and Neoseiulus cucumeris were released on citrus seedlings using self-made releasers.P.citri was well controlled on the 10 th day after release,but after 40 days of release,N.cucumeris was not as effective as N.californicus.This may be due to N.californicus being more Strong resistance to high temperatures and drought. |
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