Study of the Efficiency of the Aqueous Extract of Azadirachta indica’s Seeds and Deltamethrin on Jatropha curcas L. Insect Pests: Case of Calidea panaethiopica (Hemoptera: Scutelliridae) and Aphtona whitfieldi (Coleoptera: Chrysomelidae)

摘要

The efficiency of an aqueous extract of Azadirachta indica’s seeds and deltamethrin 12.5 EC was tested for the control of Calidea panaethiopica and Aphtona whitfieldi populations, two major insect pests of Jatropha curcas L. in Burkina Faso. This study was conducted in 2013 during the dry season and in 2014 during the raining season. In the laboratory, tests of toxicity by contact on paper blotter and by ingestion on organs of the plant and their repulsive effect on paper blotter were performed in vitro on the insect pests adults caught on J. curcasplantations as compared with controls. The aqueous excerpts of neem seeds were prepared at different lengths of steeping (12 h, 24 h and 48 h) and the deltamethrin 12.5 EC was diluted at different doses (4 ml, 8 ml and 16 ml/L). The results of this experiment showed the evidence of the efficiency of the doses 8 ml/L and 16 ml/L of deltamethrin 12.5 EC, and those of 24 h and 48 h for the excerpts of neem seeds. These efficient doses were evaluated in the field in 2013 and 2014. The highest decreases of C. panaethiopica (0.327) and of A. whitfieldi (0.501) populations were recorded with the 16 ml/L dose of deltamethrin in 2014 raining season. During the 2013 dry season, more insect pests were recorded (0.389 for C. panaethiopica and 0.679 for A. whitfieldi) with that dose. But these results were not significantly different from those of 8 ml/L. Regarding the A. indica extracts, the best decrease of populations in the 1st year (0.36 for C. panaethiopica and 1.278 for A. withfieldi) was recorded with the 48 h maceration. But in 2014 because of the effect of rainfalls that dose was less effective than that of 24 h maceration with 0.399 for C. panaethiopica and 1.208 for A. whitfieldi. The efficiency interval of the tested insecticides was two to three weeks in low or no rainfall conditions and one to two weeks in rainy season conditions.