The Effects Of Plant Volatiles On Sexual Orientation And The Chemoreception Function Of Odorant Binding Protein AlucOBP8 Of Apolygus Lucorum(Hemiptera:Miridae)

The green plant bugs(Apolygus lucorum) have become the main pest in cotton field with the spreading of Bt transgenosis cotton. The A.lucorum is difficult to manage due to its multi-hosts, host alternation and high mobility. Now managing and controlling the pests with their sex pheromone have become hot following the theory of integrated pest management(IPM) of which the “Push-Pull” strategy is a typical example. So we are demanded to explain the insect chemical communication with pheromone on the behavior level and molecular biology level. This research set about two points and we are expecting that our tentative exploration on the recognizing of A.lucorum which represents the mirids to sex pheromone could provide some help to the research latter.The main contents of the experiment include two part below: 1. At present it is intractable of the component of sex pheromone of mirid bugs to identify, the synthetic lure of sex pheromone of mirid dose not have a high biological activity and the sex pheromone which has effect in field does not work indoors. We got the preliminary study on the interaction between sex pheromone and plant volatiles on A.lucorum males using the H-tube olfactometer. On the behaviour level we found that the sex pheromone of which the components(E)-4-oxo-2-hexenal and(E)-2-hexenyl butyrate in a ratio of 3:2 could not attract the males of A.lucorum in H-tube olfactometer(P=0.5371),and the sex pheromone lure added to cotton volatile still had no attraction to A.lucorum males(P=0.4838). Then we made the A.lucorum feed on cotton leaves and found that the sex pheromone lure with cotton volatile worked(P=0.0022), but the lure without cotton volatile inefficacious(P=0.5002). The results showed that the plant volatiles had a key messenger function in the course of A.lucorum males searching for spouse. On this basis, we fed the bugs using different host and found that in the cotton volatile environment the A.lucorum fed on cotton, artemisinine and alfalfa which were main host in nature had strong tendency to sex pheromone with cotton volatile(P<0.05), and A.lucorum fed on bean and corn which were rare host in nature had no tendency(P>0.10). The discovery could not merely explain the phenomena difference between field and indoor of A.lucorum recognizing the sex pheromone, but also showed that in the long coevolution of miridae insects represented by A.lucorum and natural environment, feeling the host existing had become the precondition and foundation of mating of bugs in order to make the population flourishing.2. We cloned, expressed and purified an odorant binding protein of A.lucorum which named Aluc OBP8. Through the fluorescence competitive binding assays which included 7 latent sex pheromone analogs and 33 cotton volatiles, we found Aluc OBP8 could bind none of the sex pheromone components but could bind two host volatiles effectively. The two volatiles were α-humulene and dodecyl aldehyde, of which the dissociation constant respectively were 8.74μmol/L and 9.99μmol/L. Then we measured the attraction of these two odours to A.lucorum using H-tube olfactometer. The results showed that the dodecyl aldehyde could expel males of A.lucorum significantly and neither odour could attract the bugs of both gender. So we considered the Aluc OBP8 might be a GOBP binding plant volatiles, but we did not exclude the possibility of other function in the life history such as participation in sex pheromone recognizing indirectly.