Effects of herbicide glyphosate on fitness attributes of Zygogramma bicolorata pallister

This study is on the effects of glyphosate on biology and fitness of biocontrol agent Zygogramma bicolorata against parthenium weed. Bioassay of glyphosate was conducted using a minimum range of the field- recommended dose (0.408%). Results showed that indirect exposure to glyphosate caused significant mortality of I, II, III, and IV instar Z. bicolorata grubs. Maximum mortality (23.60%) was recorded in the first instar. The total larval developmental period was significantly prolonged in the group exposed to glyphosate (19.50 days) compared to the unexposed group (17.73 days). The application of glyphosate also caused a variation in pupation period. In addition, the longevity of both male and female Z. bicolorata was negatively impacted by glyphosate treatment. Thus, it is concluded that glyphosate has an ecotoxic effect on Z. bicolorata with potential implications for the effectiveness of Z. bicolorata as a biocontrol agent against parthenium.