The Study of the Fitness Difference of Helicoverpa Armigera (Hübner) and Helicoverpa Assulta (Guenée) Fed with Different Pepper Varieties
|School||Henan Agricultural University|
|Course||Agricultural Entomology and Pest Control|
|Keywords||Bollworm Tobacco budworm Pepper varieties Host is suitable degree Salivary glands Protein differences|
Two sibling species Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) are serious crop pests in China . They have the similar morphological,biological and ecological characterstics, they can even hybridize with each other. However, their host range are quite different. The former is a typical polyphagous species, but the latter is an oligophagous species. Capsicum annuum L. is an important economic crop, with a long culture history in China, the varieties resource is richest, and the cultivated area is widest. In Henan province, it is an important economic crops. Both H. armigera and H. assulta can damage pepper, and the field investigation found that H. assulta is more harmful to pepper than H. armigera, but also there have some literatures pointed that pepper is the host plant of H. assulta, not H. armigera.In order to proven whether or not the Capsicum annuum L. is the host of H. armigera and H. assulta or suitable host , make the fitness difference of H. armigera and H. assulta on different pepper varieties clearly, and provide theoretical basis to sift some insect-resistant pepper varieties , we have chosen four pepper varieties to study. The main results are as follows:1.The analysis of pungent constituents on four pepper varieties: By using GC-MS, the pungent constituents of four pepper varieties were determined. The results showed that: the pungent constituents contains five kinds of constituent, they are C17H27NO3 , C18H27NO3 , C18H29NO3 , C19H29NO3 and C19H31NO3. The contents of these on No.2 Yuyouxianla is highest , followed by Yuyilüguan,Yuyimoxioudajiao and No.12 Yutianjiao. Capsaicine is the main pungent constituent in pepper, the content of it on No.2 Yuyouxianla is highest, followed by Yuyilüguan and Yuyimoxioudajiao, No.12 Yutianjiao is lowest.2.The feeding behavior of H. armigera and H. assulta on the four pepper varieties: Effects of four pepers varieties (No.2 Yuyouxianla, Yuyilüguan, Yuyoumoxioudajiao, and No.12 Yutianjiao) on the feeding behavior of H. armigera and H. assulta under experimental conditions were studied comparatively. The results show that (1)The larvae’s selectivity of Newly-hatched、3rd instar and 5th instar of two Noctuidae insects were basically identical, with the content of capsaicine reducing , the selectivity was enhanced, the percentage of feeding amount was also increased, but the selectivity of H. assulta was stronger than H. armigera. (2) With the content of capsaicine reducing, the feeding time and recess time of two Noctuidae insects were both increased, but the activity time was reduced. Compared with H. armigera, the feeding time and recess time of H. assulta were longer, the activity time was shorter. The feeding time on No.2Yuyouxianla and Yuyimoxioudajiao, the recess time on Yuyimoxioudajiao, and the activity time on Yuyilüguan of two Noctuidae insects were difference significantly , the activity time on Yuyimoxioudajiao was extremely significant difference. Among the four pepper varieties, the feeding amount of H. assulta on No.12 Yutianjiao was significantly higher than H. armigera.3.Nutritional function of larvae reared on four pepper varieties: (1) The approximate digestibility and the efficiency conversion of ingestion of H. armigera showed differences in four pepper varieties, and the difference between No.12 Yutianjiao and No.2 Yuyouxianla was significant; (2) The efficiency conversion of ingestion and efficiency conversion of digestion of H. assulta showed differences, and the difference on No.12 Yutianjiao was significant,but the relative consumption rate wae significantly lest than Yuyilüguan and No.2Yuyouxianla.(3) Compared with H. armigera, the efficiency conversion of digestion of H. assulta on No.12 Yutianjiao was significantly higher than H. armigera.4.The effects of four pepper varieties on the experimental population increase of H. armigera and H. assulta: (1) H. armigera could normaly complete a generation in all four pepper varieties. With the content of capsaicine increasing, the development duration of H.armigera larvae were prolonged , the survival rates were declined. So it leaded to a decrease both net reproductive rate and Innate capacity of increase on No.12 Yutianjiao. (2) The development duration, survival rates and population increase of H. assulta are basically identical with H. armigera .(3) Development duration, survival rates and population increase of H.assulta reared on four pepper varieties were much worse than H.armigera,1eading to the growth rate of population lower than H armigera.5.The oviposition behavior and the damage level analysis of H. armigera and H. assulta on the four pepper varieties:At the field conditions, the oviposition behavior and the damage level of Helicoverpa armigera and Helicoverpa assulta on the four pepper varieties with different contents of pungent constituent were studied comparatively. The results showed that: (1) The numbers of mean eggs of Helicoverpa armigera among the four pepper varieties have no significant difference, but the total numbers of mean eggs per plant on No.12 Yutianjiao is obviously more than No.2 Yuyouxianla and Yuyilüguan. The numbers of mean eggs and the total numbers of mean eggs per plant of Helicoverpa assulta on No.12 Yutianjiao are significantly different from No.2 Yuyouxianla .The numbers of mean eggs and the total numbers of mean eggs per plant of Helicoverpa assulta deposited on the four pepper varieties were higher compared with that of Helicoverpa armigera; (2) The rate of wormyfruit and the larval survival on No.12 Yutianjiao were highest, followed by Yuyimoxioudajiao, Yuyilüguan, and No.2 Yuyouxianla. Feeding with the fruit of Yuyimoxioudajiao, the pupation rate of larvae was highest and the number of adult emergence was also most , followed by No.12 Yutianjiao, two other varieties are relatively lower; with the increase of the content of capsaicine in the four pepper varieties, the number of eggs and the damage level of the two noctuidae insects are significantly reduced.6.The digestive enzyme of salivary gland of H.armigera: Using 2-DE technology, we analysed the digestive enzymes after feeding the artificial diet which contains the fruit of four pepper varieties. The result showed that the protein on salivary gland was differentily expressed after feeding, we find 20 protein points to determine to determine, and made 15 protein points clearly .