Predation Of Apolygus Lucorum To Cotton Insect Pests And Its Molecular Detection

Apolygus lucorum (Hemiptera: Miridae) is a key insect pest on cotton in China, whereas this pest also can prey on some small insects and insect eggs. In order to understand the feeding habit and evaluate the ecological function of A. lucorum in the agro-ecosystem, we assessed the predation of A. lucorum on Helicoverpa armigera eggs, Aphis gossypii and Bemisia tabaci nymphs both in laboratory and in the field. The main results were summarized as follows.The functional responses of the predation of A. lucorum adults and nymphs on H. armigera eggs, A. gossypii and B. tabaci nymphs belong to Hollingâ…¡type. The feeding amount increased with the increasing number of preys or age of predators. The feeding amount of H. armigera eggs, A. gossypii nymphs and B. tabaci nymphs were 11.2, 6.8 and 2.0 for the second instar nymph, 31, 12.2 and 6.8 for the fourth instar individuals, and 35, 13.6, 6.4 for for the 5-day-old adults, respectively. There are no significant differents in feeding amount between male and female.Development and survivorship of nymph A. lucorum varied greatly between different food sources. The survival rates of A. lucorum nymphs were very low when only provided animal food. A. lucorum could complete nymphal development on H. armigera eggs with low survival rate (13.3%), but could not on A. gossypii or B. tabaci nymph. The survival rates of A. lucorum nymphs fed on plant foods (i.e. green bean or cotton leaf) were between 37% and 46%, whereas that of individuals on mixed food (inc. the above plant and animal foods) were over 50%. In total, both plant and animal food provided together are available for the development and survival of A. lucorum nymph.We designed the specific primer of H. armigera and A. gossypii by using the sequences of cytochrome oxidase subunit (COâ… ) gene. The primer of H. armigera can amplify the band only in H. armigera, can't get the band in other insects. We use this primer to test the A. lucorum which fed on H. armigera eggs in laboratory. The results indicated that the target DNA of H. armigera was detected in guts of A. lucorum, but not detected in A. lucorum without feeding on H. armigera eggs. And there are no target DNA in A. lucorum which collected in cotton fields. The primer of A. gossypii can amplify the band only in A. gossypii. It showed that this is specific. Molecular identification of A. lucorum fed on A. gossypii was tested with the specific primer. The results indicated that the target DNA fragement of A. gossypii was detected in A. lucorum. We use the primer of A. gossypii to test 309 A. gossypii individuals collected in cotton fields, there are 17 individuals had target DNA of A. gossypii.In conclusion, A. lucorum can feed on H. armigera eggs, A. gossypii and B. tabaci nymphs, and the predation belongs to Hollingâ…¡type. A. lucorum is mainly phytophagous, and is rather carnivorous. The result proved that A. lucorum can prey on A. gossypii in the fields.