Field and laboratory assays on Phthia picta (Coreidae) and Murgantia histrionica (Pentatomidae) using organic pesticides

This study evaluated the effect of organic pesticides on Phthia picta and Murgantia histrionica with laboratory and field assays. Also P. picta was tested under cage on field conditions. Phthia picta was grown and tested with tomato and for M. histrionica was used leaves of cabbage. On field conditions, M. histrionica was probed in kale plants. Mortality was estimated in laboratory experiments each 12 hours, and on cage test each 24 hours until 72 h, and trial field 1, 3, 5 and 7 days with insecticides (Bacillus thuringiensis, azadirachtin, pyrethrin, Beauveria bassiana, and spinosad). Data were analyzed with an ANOVA and differences were separated with LSD (p < 0.05). Our results of laboratory on P. picta were: azadirachtin produced 100 % of mortality with 0.4 % at 24 h and with 0.6 % at 12 h, and similar mortality (91%) was obtained with spinosad 0.6 %. On field conditions and cage test, spinosad (0.6 %) had max mortality (60%) after 48 h, B. thuringiensis (0.16 %) had maximum mortality (30%) after 120 h, and azadirachtin (0.4 %) was ineffective. On field conditions and non-uniform population, B. thuringiensis combined with spinosad, azadirachtin or pyrethrin produced mortality similar to control. In test laboratory of M. histrionica and 0.6% a. i., spinosad and pyrethrin caused 100% mortality (at 24 h), and B. bassiana had maximum mortality (83 %) after 60 h. In field conditions with non-uniform population, results were inconsistent with laboratory test; however we observed high decrease on population with B. thuringiensis combined with spinosad or azadirachtin.