Age, mating status and sex influence food consumption and utilization efficiency of Parthenium beetle, Zygogramma bicolorata Pallister.
A study was designed to evaluate the combined effects of age, mating status and sex on the feeding attributes of the Parthenium beetle, Zygogramma bicolorata Pallister when fed on Parthenium hysterophorus L., a serious weed of wastelands, pastures and agricultural fields. Newly emerged adult beetles were placed in two groups. Adults of the first group were kept unmated and their daily feeding and growth attributes were assessed for the following 20 days. By comparison, males and females of the second group were allowed to mate on the 11th day (attainment of sexual maturity) and mating pairs were kept individually to assess their daily feeding and growth attributes for the following 10 days. Results revealed higher consumption and growth rates of Z. bicolorata females than males. In contrast, males exhibited higher food conversion efficiencies than the females. However, food consumption and growth rates of unmated adults were higher than mated adults. Age-based regression graphs revealed decreased consumption rates, conversion efficiencies and growth rates of Z. bicolorata adults with increase in age. However, the mean body biomass of adults increased with increasing age. This further suggested compensatory feeding in Z. bicolorata adults as they age. The present findings may be helpful to mass-multiply Z. bicolorata in laboratories for the biocontrol of Parthenium weed in agricultural farms on the Indian subcontinent.