Residual toxicity of seven pesticides to Trichogramma dendrolimi
Author of the article:FENG Hong-Zu1** LIU Jun 1 WANG Lan1 LI Zhi-Gang3 XU Jian-Jun2***
Author's Workplace：1. Tarim University/Engineering Laboratory of Featured Fruit Tree in Southern Xinjiang, XPCC/Scientific Observing and Experimental Station of Crop Pests in Alar; Ministry of Agriculture, P. R. China/Southern Xinjiang Key Laboratory of IPM of Tarim University, Alar 843300, China; 2. Institute of Plant Protection, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China; 3. Forestry Bureau of Aksu, Aksu 843000, China
Key Words：Trichogramma dendrolimi, insecticide, integrated pest management, biological control
[Objectives] To clarify the residual toxicity of common insecticides on Trichogramma dendrolimi. [Methods] The residual toxicity to Trichogramma pupae and adults of seven insecticides applied at the recommended dose was determined by simulation experiment. [Results] Avermectin and Chlorpyrifos had the highest toxicity to T. dendrolimi adults, causing 100% mortality after spraying at the recommended concentration for 1-3 days, and 70% mortality after spraying for 5-10 days. Emamectin Benzoate was less toxic, mortality rates declined to 22.2% after spraying for 7 days and to 13.3% after spraying for 10 days, which was not significantly different (P>0.05) to those produced by the control treatment (water). Spraying Gatifloxacin caused mortality of 38%-86.8% during 1-7 days, but mortality was not significantly different to the control (P > 0.05) after spraying for 10 days. Matrine had relatively high toxicity to adult T. dendrolimi with a mortality of 28.5%-82.3% after spraying for 1-7 days. The toxicity of Sulfoxaflor was similar to that of Gatifloxacin, with no significant difference in mortality compared to the control after 10 days. Methoxyfenozide had the least toxicity to T. dendrolimi among seven insecticides tested, with no significant difference in mortality compared to the control after the first 1-3 days of spraying. At the recommended dose, Chlorpyrifos had the greatest influence on the eclosion rate whereas all the other pesticides had no effect. The average eclosion rate after spraying Chlorpyrifos was 68%, which was significantly different from the control. The result showed that application of highly toxic insecticides, such as Abamectin and Chlorpyrifos, should be avoided after releasing Trichogramma as part of an integrated pest management program. The use of low residual toxic insecticides like Methoxyfenozide is recommended. In order to avoid adverse effects on Trichogramma from residual insecticide toxicity, the delay between the final pesticide application and the release of Trichogramma should be more strictly observed. [Conclusion] It provides the basic data for coordinating the chemical control and natural enemies control on integrated pest management.