Ontogenetic Changes in Feeding Behaviour and Nutrient Allocation in Zygogramma bicolorata on Parthenium hysterophorus

Parthenium hysterophorus is an invasive weed causing agricultural losses. Zygogramma bicolorata, a biocontrol agent, is widely used to manage its spread. However, little is known about how nutrient assimilation varies during larval development. This study investigates ontogenetic changes in feeding behaviour and nutrient allocation patterns of Z. bicolorata across different larval instars. Larvae were reared under controlled conditions at Banaras Hindu University, India, across four temperature regimes (15°C, 20°C, 25°C, and 30°C). Feeding parameters (consumption rate, conversion efficiency, growth rate) and biochemical metabolites (glucose, proteins, triglycerides) were analyzed using one-way and two-way ANOVA. First-instar larvae exhibited the lowest food consumption and highest utilization efficiency, whereas fourth instars showed maximal nutrient accumulation but lower developmental rates. Temperature significantly influenced feeding efficiency and metabolic reserves, affecting overall developmental progression. Understanding nutrient allocation across larval stages can enhance mass-rearing strategies for biocontrol programs. The findings emphasize the role of developmental-stage-specific feeding strategies in optimizing biological control efficacy.