Journal of Taiwan Agricultural Research

Author:Ching-Hua Kao and Edward Y Cheng

Abstract:

The diamondback moth (Plutella xylostella, DBM) has developed resistances to almost all conventional insecticides, for example, carbamates, organophosphorus compounds, synthetic pyrethroids, and insect growth regulators. The resistance and cross-resistance amongst these insecticides had been studied and clarified. A strategy by rotating selected insecticides to manage the resistant DBM has been proposed and tested in field, and the result is acceptable to farmers. From 1990 to 2000, many new insecticides with unique mode of actions were registered, and DBM control is no longer a problem for farmers. However, whether DBM also slowly develops resistance to those new insecticides is worth to study. DBM strains were collected from two largest vegetable districts, Hsi-hu and Lu-chu, for testing the resistance profile to newly registered insecticides. The test results confirmed that field DBM has developed resistance to new insecticides except diafenthiuron. The resistance ratios of abamectin and emamectin benzoate between two field DBM populations are 2500~5000 and 300~150 respectively; the resistance ratio of another GABA inhibitor, fipronil, between these two populations is 65~104. The resistance ratio of derivatives of cartap and carbamate, bensultap and benfuracarb between two different populations are 20~30 and 10~30 respectively. The resistance ratio of chiorfenapyr and spinosad between two different populations are 10 and 60 respectively. The DBM resistance to commercial product of neem extract, azadirachtin, is too high for field application practically since the high viscosity of the extracted product plugged the spray nuzzle of sprayer when the concentrated product was used.

Key words:Plutella xylostella, Insecticide, Resistance, Resistance monitoring

Download: PDF Links