Effects of different formulations of neem oil-based products on control Zabrotes subfasciatus (Boheman, 1833) (Coleoptera: Bruchidae) on beans

• Neem extracts could be prepared in a manner to enhance toxicity for Zabrotes subfasciatus.
• Nanoformulations showed better stability than no encapsulated products.
• Formulations were stable and show promise for commercial production.

The bean weevil, Zabrotes subfasciatus is a major storage pest and causes direct and indirect damage to the grains. The poor water solubility and the high degradation rate of many natural products remain a major obstacle to their development and agronomical application. This present work describes alternative methods to formulate botanical extracts of Azadirachta indica (neem) to improve its biological stability. Moreover, it highlights both the importance of the preparation of botanical products, which should be formulated with reproductive levels of active compounds, and also should be characterized by using analytical tools in quality control programs. Nanoparticles loaded with neem products and enriched botanical extracts with different quantities of azadirachtin were prepared and they were efficiently tested against Z. subfasciatus. The results showed higher stability when compared with commercial products. The biological experiments were assayed using nanoformulated neem products in powder (NC), soluble powder prepared with neem oil (SP), neem oil emulsifiable concentrate (EC), and control. Under the conditions which the experiments were installed, the emulsifiable products of the neem oils 1000 EC, 2000 EC, 4000 EC provided the highest mortality for the Z. subfasciatus. Nanoformulated neem products in powder showed greatest UV stability.

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