Dr. Perera et al., Effect of antifeedants on the diamondback moth (Plutella xylostella) and its parasitoid Cotesia plutellae, PEST MAN SC, 56(5), 2000, pp. 486-490
Two neem preparations and the bitter-tasting synthetic chemical denatonium
benzoate were tested in the laboratory as antifeedants against the diamondb
ack moth, Plutella xylostella L. The effects of the three materials on Cote
sia plutellae (Kurdjumov), a hymenopteran parasitoid of P xylostella, were
also recorded. All three materials significantly reduced the food consumpti
on of P xylostella larvae. Parasitoid cocoons were formed on approximately
half of those larvae which had been exposed to female C plutellae, regardle
ss of antifeedant treatment, but emergence of adult parasitoids from the co
coons was significantly reduced by antifeedant treatment. In terms of food
consumption and mortality of unparasitised P xylostella larvae, and emergen
ce of adult C plutellae, the effect of each antifeedant preparation was dir
ectly related to the concentration of material used, but the effects of the
neem preparations were greater than those of denatonium benzoate. However,
no adult P xylostella emerged on any antifeedant treatment, therefore some
of the parasitoids survived antifeedant treatments which were fatal to the
unparasitised hosts. (C) 2000 Society of Chemical Industry.