Insecticidal Activity Of The Scent Gland Extracts From Litchi Stink Bug And Its Fumigating Mechanism

Tessaratoma papillosa Drury (Hemiptera, Pentatomidae) is a serious pest of litchi and longan fruit and known for the scent glands, which released foul liquid when being disturbed. To understand the biological activity of the scent gland extracts from litchi stink bug, the common pests and pathogens were used to test the insecticidal activity of scent gland extracts, and there has no report about this research. The research results were as follows:The fumigation action of the scent gland extracts was tested by flask sealed fumigation. The scent gland extracts of female and male adults have significant fumigation effect on the tested pests. After fumigating for 12h, the LC50 values of scent gland extracts of the female and male adults to Aphis craccivora Koch, Ceratovacuna lanigera Zehntner, Aphis gossypii Gloyer, Rhopalosiphum maidis Fitch, Subtropical Agriculture Rehash, Bemisia tabaci Gennadius and Brontispa longissima Gestro were 1.0743μL/L,1.5324μl/L,3.6802μL/L, 1.4398μL/L,1.9495μl/L,1.8862μL/L,0.9910μL/L and 1.4038μL/L,1.5327μL/L,3.6351μL/L,1.5858μL/L,0.9673μL/L,0.9904μL/L,0.9536μL/L, respectively. And after fumigating for 24h, the LC50 values of scent gland extracts of the female and male adults to Sitophilus oryzae (Linnaeus), Rhyzopertha dominica Fabricius, Callosobruchus maculatus Fabricius, Curpophilus hemipterus Linnaeus were 0.4803μL/L,6.3803μL/L,2.5936μL/L, 3.7925μL/L and 0.5247μL/L,6.3125μL/L,2.4068μL/L,3.7753μL/L, respectively.The contact action of the scent gland extracts of stink bugs to pests were analyzed by methods of immersion, culture dish membrane and drop respectively. The scent gland extracts of female and male adults have remarkable action of contact poison on the tested pests. After treating for 12h, the LC50 values of the scent gland extracts of female and male adults to A. craccivora, C. lanigera, A. gossypii, R. maidis, S. Agriculture, B. tabaci and B. longissima were 11.2703 mL/L,6.2152 mL/L,4.7612 mL/L,23.9420 mL/L,1.1769mL/L,1.0323 mL/L 0.0172μL per insect dose and 8.5769 mL/L,7.6450 mL/L,4.1751 mL/L,9.8741 mL/L 1.4276 mL/L,1.3245 mL/L,0.0103μL per insect dose, respectively.The repellent action of the scent gland extracts of stink bugs to the aphids and common storage pests were tested by blade applicator method and membrane filter method, the results showed that the scent gland extracts of female and male adults have remarkable repellent effect to the tested pests. After treating for 12h, the repellent rate of the scent gland extracts of female and male adults to A. gossypii, A. craccivora, R. maidis, were respectively 83.98%, 91.01%,69.19% and 92.89%,77.96%,64.87%; the repellent rate of the scent gland extracts of female and male adults to S. oryzae, C. hemipterus, C. maculates, R. dominica were 68.71%,96.27%,33.33%,97.62% and 72.27%,94.09%,50.00%,96.39%, respectively. In addition, the scent gland extracts have remarkable selective repellent effect and nonselective repellent effect to B. longissima by blade applicator method. The selective repellent effect increased with the raise of time and concentration. When dealing with 18h, 36h,48h, the concentration of 0.001mL/L, the relative repellency rates of the scent gland extracts of female and male adults to B. longissima were-24.91%,12.00%,31.07% and-15.07%,13.65%,18.77%. When the concentration of 10 mL/L, the relative repellent rates were 82.22%,75.62%,66.36% and 62.81%,82.22%,50.75%, respectively. But the nonselective repellent effect decreased with the raise of time and concentration. When dealing with 18h,36h,48h, the nonrelative repellency rates of the female and male adult stink bugs scent gland extracts to B. longissima were minimumat the concentration of 0.001mL/L, 55.56%,38.10%,35.71% and 70.18%,47.62%,35.71%, respectively. The nonrelative repellent rates were maximum at the concentration of 10 mL/L,83.33%,56.79%,47.62% and 90.23%,81.63%,71.43%, respectively.The changes of zymogen protein's content and the main enzymes'activity of S. oryzae were tested after fumigation treated with the scent gland extracts of the litchi stink bugs. The results showed that the scent gland extracts of the litchi stink bugs have strong inhibitory action to the main enzymes'activity of S. oryzae. The contents of soluble protein in the insects treated with the scent gland extracts of the litchi stink bugs were lower than control, and the contents of soluble protein in the treated insects decreased with the increase of the concentration. The scent gland extracts of the litchi stink bugs had the effect of inhibiting all the specific activity of AChE, ACP, ALP, GSTs and POD of S. oryzae. After treated with the scent gland extracts of the litchi stink bugs, all the specific activity of AChE, ACP, ALP, GSTs and POD of S. oryzae were lower than control, and all the specific activity of AChE, ACP, ALP, GSTs and POD of S. oryzae decreased with the increase of the concentration and time.The results above showed that the scent gland extracts of the litchi stink bugs had significantly insecticidal and bactericidal biological activity. The extracts had obvious contact, fumigation and repellent activities to pests be tested. Inhibiting the enzyme activity in the tested insects is one of the mechanisms of the scent gland extracts of litchi stink bugs. Therefore, the extracts of litchi stink bug scent gland could be used as a class of bio-pesticides, and it was necessary to do further research on screening its active substance.