Sublethal Effects of Fenoxycarb on the Plutella xylostella (Lepidoptera: Plutellidae)

The effects of fenoxycarb, a Juvenile hormone analogue, at sublethal concentrations were tested on some biological parameters of Plutella xylostella (L.) in two consecutive generations. The calculated LC(10), LC(25), and LC(50) values of the insecticide were 21.58, 43.25, and 93.62 mg/liter on third-instar larvae, respectively. Fenoxycarb significantly reduced pupal weight and oviposition period in parent generation. In addition, the fecundity of treated groups (LC(10) = 71.06, LC(25) = 40.60 eggs per female) in parents was significantly lower than control (169.40 eggs per female). Although fenoxycarb could not affect gross reproductive rate and death rate, it decreased net reproductive rate, intrinsic rate of increase, finite rate of increase, and birth rate in offspring generation. Also, mean generation time and doubling time of treated insects was significantly longer than control at LC(10) level. Therefore, the data from this study suggested that fenoxycarb could adversely cause population decline in the subsequent generation.