Relationship Between Host Selection And Host Performance Of Helicoverpa Armigera

Helicoverpa armigera(Hübner) is a kind of polyphagous insects which belongs to Lepidoptera, Noctuidae. They can eat a variety of plants especially about Malvaceae, Solanaceae, Leguminous plants and occur to different extent from north to south in our country.Interaction between H. armigeraand host plants has always been a hotspot in research of plant-insect interactions. But H. armigeraas a polyphagous insect, how to determine host plants, and what stage palayed a key role in the process of ascertaining host plants remains elusive. To address this question, we chose 16 plants as test plants from 11 families according to host fitness, that contained 5 suitable host plants, 4 less suitable host plants, 3 least suitable host plants and 4 non-host plants. Then we respectively studied three stages about female adult oviposition selection, neonate feeding selection and no choice larva feeding performance of H. armigera. In proper order to get results and defined them as adult selection spectrum, neonate selection spectrum and larva survival spectrum. we compared the size of the three stages host spectrum to makesure the key link of H. armigera to host plants. Main results were as following.1. H. armigera female adults placed a strong spawning choice preference in the vast majority of the test plants. Chi-square test indicated that including 11 plants(tobacco, eggplant, cotton, carrot, tomato, red pepper, corn, celery, soybean, peanut and poplar deadwood) the number of H. armigera female adults chose plants was significantly higher than control. So these were host plants of female adult oviposition selection and defined as adult selection spectrum.2. H. armigera neonates had a great feeding selection adaptability in most of the test plants. Chi-square test showed the number of H. armigera neonate chose plants was significantly higher than control including 13 plants(corn, eggplant, tobacco, soybean, carrot, cucumber, spinach, tomato, cotton, celery, peanut, red pepper and welsh onion), which were host plants of neonate feeding selection and defined as neonate selection spectrum.3. H. armigera larvae existed very big difference on no choice larvae feeding survival and performance in different test plants. Only including 6 plants(carrot, tomato, tobacco, cotton, soybean and celery) as foods could make H. armigera larvae grow smoothly until success of pupation and eclusion. These were host plants of no choice larvae feeding performance and acted as larvae survival spectrum.4. We compared the size of 3 stages, neonate selection spectrum(13 plants) was two plants wider than adult selection spectrum(11 plants), the most narrow was larva survival host spectrum(6 plants) which all 6 plants were included in adult selection spectrum(11 plants). Adult selection spectrum(11 plants) was contained in neonate selection spectrum(13 plants) except poplar deadwood.Above all, to a great extent, H. armigera female adults oviposition selection determined neonate’s feeding range, but neonates had the ability to select other plants out of adult host spectrum. Meanwhile neonate selection stage and adult selection stage could only restrict host range of H. armigera to a certain extent. Due to more urgent demand for plants nutrition, no choice larvae feeding performance put forward higher request to host plants providing. It resulted in host range of larvae survival stage was significantly narrower than other two stages. Therefore, H. armigera no choice larvae feeding performance stage played the most vital role in determining host plants of the three stages.