Assessment of the ancestral use of garlic (Allium sativum) and nettle (Urtica dioica) as botanical insecticides in the protection of mesquite (Prosopis laevigata) seeds against bruchins

Abstract

Currently, Prosopis laevigata (mesquite) has been affected by the Bruchinae coleoptera pest, whic feeds on its seed and causes significant losses in production and grain storage. In the Hñähñu community El Alberto (Ixmiquilpan, Hidalgo, Mexico), the use of aqueous extracts from garlic and nettle as botanical insecticides against different pests in agricultural fields is a known practice. Herein, we assess the efficacy of the method known by locals in the protection of mesquite seeds. Two tests were conducted: 1) Insecticidal effect on adult bruchins, and 2) Seed preservation test from Bruchinae infestation, with a germination test in seeds exposed to the treatments. There are probable insecticidal effects on immature stages of Bruchinae since there were no mortality effects on their adults during the first test. Mortality on adults in the second test was 75.6% with garlic and 50% with nettle. Nettle extract had more efficacy in seed protection with an infestation rate of 4%, whereas 27.5% of the seeds exposed to garlic extract were infested. Seed germination rate was 2.38% with nettle extract, and 1.19% with garlic extract. The method known by local inhabitants requires modifications to increase its efficacy and possible use in Integrated Pest Management in the future.