Reproduction Behaviour of Insecticide Susceptible and Resistant Plutella xylostella (Linnaeus)

Reproduction behaviour of insecticide-resistant and susceptible populations of diamondback moth, Plutella xylostella (Linnaeus), a challenging insect-pest of cruciferous vegetable crops round the globe, is reported. The oviposition period differed significantly for pairs from resistant population, the maximum being 8.33±0.577 d. Both the resistant and susceptible moths preferred untreated surface over insecticide-treated surface for egglaying. The fecundity was maximum (185.0) when pairs from resistant population were mated and minimum (135.3) when both the males and females were from the susceptible population. In spite of the higher fecundity of the resistant moths, their reproductive effort (fecundity × egg-size) could not register a higher value given to the smaller egg-size (0.023 mm³) as compared to the bigger eggs (size = 0.035 mm³) of the susceptible ones. Hatchability of the eggs of pairs of the susceptible population was the maximum (79.28%) than pairs from that of resistant populations (74.10%). Certain pronounced reproductive behavioural differences were registered in the insecticide-resistant P. xylostella as compared to the susceptible one. This knowledge may help to find management solution against diamondback moth.