Optimization Of Noctuid Floral Attractants And Associative Learning Behaviour Of Helicoverpa Armiqera Adults To Key Floral Components

ABSTRACT:In this disertation, the author tested the electrophysiological response of Helicoberpa armigera males and females to 14 common floral volatiles, then conducted a serial of field trapping experiments with candidate floral attractant blends mixed by Mixture Uniform Design, the key floral volatiles were further tested for associative learning study of H. armigera moths and their polysemy, finally designed a novel trap specifically to Lepidopteron adults. The main results are summarized as follows.1. H. armigera males and females show similar EAG profile to the floral volatiles, among which β-phenylethyl alcohol, benzaldehyde, and benzyl acetate exhibited strong stimulative effect on both sexes;2. The field trapping experiments show that the floral-based attractants exhibited generic attraction effect, the trapped species included H. armigera, Argyrogramma agnata, Spodoptera litura, Spodoptera exigua, Hymenia recurvalis, Ostrinia furnacalis, Cnaphalocrocis medinalis, and Maruca testulalis, etc. Benzaldehyde and benzyl alcohol, with the shortest side-chain among the tested compounds, had significant negtive effect on almost all the captures. Phenylacetaldehyde, benzyl acetate, and salicylaldehyde was the most important active components, but the interactions among them are very complex. We found that the phenylacetaldehyde showing the strongest attractiveness could mask the attractive effect of the other two key floral volatiles, suggesting that Lepidopteron adults showed odour preference hierarchy during flower-visiting, and which could be changed with experience. Benzyl acetate and β-phenylethyl alcohol were responsible for the flower-visiting differentiation of noctuid moths and pyralid moths, and both the blend ratio test and the dosage test indicated that benzyl acetate and phenylacetaldehyde interacted as additive effect.3. The associative learning of H. armigera moths to two key floral volatiles. Naive moths could not discriminate benzyl acetate and phenylacetaldehyde, and the pre-exposure under these volatiles could not improve the acceptance of the moths to the volatiles used in exposure treatments. However, the phenylacetaldehyde conditioned group (conditioned stimulus:the floral volatiles, unconditioned stimulus: sucrose solution) altered their odour preference after conditioned, which was occurred at CNS level.4. The polysemy of floral volatiles. Our experiment indicated that the binary floral attractants of benzyl acetate and phenylacetaldehyde exhibited fairly strong effect on the oviposition, and also played an important role in their mating.5. The author preliminarily designed a novel trap special for Lepidopteron adults, which has infinite trapping capicity with the volume being only 1% of traditional design; and the trapping selectivity of Lepidopteron species, natural enemies, and pollinator, was via a simple net structure.