This study was conducted to evaluate the effect of three concentrations (10, 20 and 30%) of three Plant
extracts: Thevetia, (Thevetia peruviana), Neem (Azadirachta indica) and Common Oleander (Nerium oleander)
against the fourth instar larvae of greater wax moth, G. mellonella and the mortality percentages were
calculated. In comparison to the control, mortality rates were higher at Neem treatments, followed by Common
Oleander and Thevetia. In addition, the values of LC50 were 12.656, 20.268 and 23.416% respectively. In the
fourth instar larvae treated with the three studied plant extracts, the activity of the enzymes Lactate
Dehydrogenase (LDH), Glutathione S-Transferase (GST), ATPase-acetylcholinesterase, and Alpha esterases was
assessed. The results showed that, in comparison to the control, LDH activity increased following treatment
with neem and common oleander. The levels of Glutathione S-transferase (GST) and alpha-esterases increased
following treatment with Common Oleander and Thevetia extracts. In contrast, ATPase activity showed a
marked decrease across all treatments, while acetylcholinesterase (AChE) activity declined after exposure to
Common Oleander and Thevetia. Overall, Neem and Common Oleander extracts exhibited stronger effects
compared to Thevetia, and all three plant extracts were more active than the untreated larvae.