Ontogenetic Changes in Feeding Behavior and Nutrient Allocation Patterns in Mexican Beetle (Zygogramma bicolorata) Pallister on Parthenium hysterophorus L

Parthenium hysterophorus L. (Asteraceae) is a noxious weed found in agricultural fields, pastures, and wastelands across tropical regions. It significantly reduces crop yields and poses serious health risks to humans. The Mexican beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), has emerged as one of the most effective biological control agents against this weed. However, no previous research has examined the beetle's nutrient assimilation. This study evaluated the feeding behavior and nutrient assimilation in the larvae of Z. bicolorata when feeding on P. hysterophorus. The findings showed that the first instar larvae had the lowest food consumption rates and accumulated minimal amounts of glucose, proteins in their bodies. These larvae demonstrated compensatory feeding behavior, achieving the highest food utilization efficiency and developmental rates. In contrast, the fourth instar larvae exhibited the highest food consumption and conversion efficiency but had the slowest developmental rates. Notably, the fourth instar larvae accumulated the largest food reserves. These results provide valuable insights for laboratory-based mass-rearing programs for Z. bicolorata, though further field trials are necessary to validate these findings.