INFLUENCE OF TEMPERATURE ON TOXICITY OF 2 PYRETHROIDS TO GRASSHOPPERS (ORTHOPTERA, ACRIDIDAE)

Nymphs of Camnula pellucida and Melanoplus bivittatus were sprayed with alphamethrin at 10 or 20 g/ha (equivalent to effective field rates), deltamethrin at 6 g/ha, or alphamethrin at 10 g/ha combined with diazinon at 300 g/ha, and transferred to constant temperatures of 15, 19, 23, 27 or 31°C. Mortality rates were greater and occurred more rapidly at higher temperatures. On the 2nd and subsequent days after treatment, mortalities at 23, 27 or 31°C did not differ significantly. Mortality at 19°C was significantly lower than at 23-31°C, and mortality at 15°C was lower than at 19°C. -from Author