Efficacy and residues of permethrin-incorporated nets used to protect maize grains post-harvest

BACKGROUND Pest control in post-harvest food storage represents a great challenge in the sustainable prevention of food losses, and insecticide-treated netting may represent a valid alternative to traditional practices such as the direct application of insecticides. In our work, the efficacy of a permethrin-incorporated net, in combination with polypropylene or jute sacking, was tested for the control of Sitophilus oryzae. Contamination of maize grain by permethrin from the treated netting was also evaluated. RESULTS A 98% control of S. oryzae was achieved using permethrin-treated netting. Both jute and polypropylene acted as additional barriers, increasing efficacy to 100%. The results also showed the contamination of maize kernel by permethrin released from the treated netting. The concentration of residues in maize kernels increased with increasing temperature; however, use of jute or polypropylene significantly reduced (by 87% to 97%) the concentration of residues transferred to maize kernels. CONCLUSIONS Permethrin-treated netting provided a high level of efficacy in the post-harvest protection of maize. Several factors influenced permethrin residue concentrations in grains when treated nets are used. Therefore, solutions should be found to prevent contamination of food stored in the bags that are treated with insecticides. © 2017 Society of Chemical Industry