Studies On The Larval Feeding Behavior And Chemosensory Proteins Of Helicoverpa Armigera H(?)bner And Helicoverpa Assulta Guenée

The sibling species Helicoverpa armigera(Hubner) and H.assulta areserious crop pests in China. They have the similar appearance and feeding behavior,but there host-plant ranges are quite different . H.armigera is a typical polyphagousspecies, while H.assulta is an oligophagous species with a relatively narrow host plantrange, and mainly feeds on plant species in Solanaceae such as tobacco ,hot pepper andseveral Physalis species. The two species can occour in tobacco at the same time ,andthey can hybridization each other. We research on feeding behavior and theelectrophysiological responses of two species , in order to clarify the susceptiblemechanism to the invironmental information. The results is as following:Helicoverpa armigera and H. assulta with different experience affected the larvalhost-plant preference: we reared spectively H. armigera and H. assulta withcotton, tobacco and pepper , host-plant preference of fifth-instar caterpillars wastested by using a two-choice leaf-disk assay, significantly different in their feedingpreferences. H. armigera reared with cotton and tobacco more preferred to feed oncotton and tobacco, but H. assulta preferred feed on tobacco no matter which plantreared. The pepper almost didn't affect the feeding preference of H. armigera . Thisindicated that the feeding experience of H. armigera affected host-plant preferenceof its larval while didn't affect H. assulta.In all, two species are preferred to feed ontheir main host-plant.The physiological responses of the gustatory organ on the maxillary to different components of different H.armigera species : There are four styloconic contact chemoreceptors on the maxillary galeae of lepidopteral larvae: a medial styloconic sensillum and a lateral styloconic sensillum on each side, which are assumed to contain the main taste receptors involved in phytochemical perception.. They are very important to feeding preferences. Tip-recording method was used to examine the electrophysiological responses to different concentration of sucrose, insitol and sinigrin of the two species. Results showed that cells sensitive to sucrose exist in lateral styloconic sensilla of two species. And cells sensitive to insitol exist in medial styloconic sensilla. While the laboratory species of H. armigera sensitive to sinigrin exist in both lateral and medial styloconic sensilla, the nature species reared on...