Insecticidal activity of garlic juice in two dipteran pests

1 Botanical products excluding pyrethroids constitute a small, but growing portion of the U.K. pesticides market. With increasing legislative pressure upon chemical pesticides such as organophosphates, interest in this sector is increasing steadily. 2 Garlic Allium sativum L. juices and extracts form the basis of several commercially available pest control products, but the performance of these products is variable, possibly due to lack of quality control upon batches of materials in the manufacturing process. 3 Some garlic products designed for use in the food industry are subjected to rigorous batch-control to ensure organoleptic consistency. We studied the insecticidal efficacy of a commercially produced food grade garlic juice using two target dipteran pests, Delia radicum (L.) and Musca domestica L. 4 Exposure of the two species to different concentrations of garlic juice revealed variability in insecticidal effect across life stages. LC50 values recorded for D. radicum were: eggs (7-day exposure) 0.8%; larvae (24-11 exposure) 26.4%; larvae (48-h exposure) 6.8%; and adults (24-h exposure) 0.4%. LC50 values recorded for M. domestica were: eggs (7-day exposure) 1.6%; larvae (24-h exposure) 10.1%; larvae (24-h exposure) 4.5%; and adults (24-h exposure) 2.2%. 5 Mortality rates caused by the garlic juice were comparable with those obtained with the organophosphate pesticide Birlane (R), indicating parity of effect at various concentrations depending on life stage. 6 We conclude that this product may provide an effective, naturally-derived insecticide for use in agricultural systems against dipteran pests.