Background: The third larval instar (L3) of Lucilia cuprina grow and feed on the living flesh of sheep.
Besides, they cause cutaneous myiasis. Herbal medicine showed potential efficacy against several
pathogens as well as insecticidal effects.
Objectives: The present work aims to investigate effect of two volatile oils, Syzygium aromaticum, Mentha
longifolia and the chemical neonicotinoid, imidacloprid (IMI), on the developmental stages of L. cuprina.
Material and Methods: Early L3 of L. cuprina were exposed to five concentrations of the three selected
compounds under investigation. The procedures were replicated four times for each concentration, and
25 larvae were used for each replicate. Average larval mortality rates were subjected to probit model
analysis for calculating LC25, LC50, LC90. Activity of acetylcholine esterase (AchE), as a measure of anticholinesterase
activity of the used compounds, was measured using acetylcholine bromide (AchBr) as
substrate.
Results: It was observed that the volatile oil LC50 of M. longifolia (3.35%) gave higher mortality of L3
compared with that produced by S. aromaticum oil (6.06%), whereas IMI was the most effective larvicidal
agent with LC50 of 0.000853%. Both volatile oils induced complete disintegration in epicuticle and the
epidermis of larval integument, and extensive damage of epithelial cells of midgut. Treatments by both
oils and IMI induced deformed adult flies, with significant larval mortality and the highest pupal mortality,
compared to controls. The AchE activity showed insignificant reduction after treatment with the LC50 of
both essential oils and IMI.
Conclusion: The inhibitory effect of the two volatile oils and IMI on the biology, histology and AchE activity
suggested that they may be considered as control agents against the myiasis causing fly L. cuprina.