Stage specific feeding attributes of Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) under fluctuating food quality.
The food is the foremost need for the existence of all living organisms and the fluctuations in its availability strongly affects the population dynamics of both the primary and secondary consumers. In the present study we have investigated the effect of food (Parthenium weed) resource fluctuations, in terms of quality, on the feeding attributes of the Parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae). This beetle is an effective biological control agent of the noxious weed, Parthenium hysterophorus L. We have abruptly changed the fourth instars and adult females of Z. bicolorata from their rearing condition of mature leaves to an experimental condition of early leaves or vice versa; and observed the effect of sudden change of food on their consumption rate, conversion efficiency and growth rates. The results revealed no significant effect of rearing and experimental conditions on the feeding attributes of fourth instars and adult females of Z. bicolorata by sudden fluctuation in the food quality. However, the fourth instars had higher feeding attributes than the adult females, proving them to be the better biocontrol agents of Parthenium weed than the adult females. However, field based studies are still needed to validate the present findings.