Evaluation of the Efficacy of Deltamethrin Incorporated Polysack Bags for the Control of Stored Grain Pests of Maize during Storage

Abstract

A study was conducted to evaluate the efficacy of insecticide (deltamethrin) incorporated bags (Zerofly) against the insect attacks during maize storage under Sri Lankan conditions. Maize sample in Zerofly sacks were stacked as the treatment and for control, untreated polysack bags were used. Maize samples that were collected before store and monthly intervals during the storage period were analysed for moisture content, weight loss due to insect damages, Thousand Grain Mass (TGM) and kernel colour. Data was analyzed using Analysis of Variance (ANOVA) by Statistical Analysis System (SAS). The moisture content of maize grains fluctuated between 11.9% -12.8% during storage period but any significant difference was not observed between bag types. The level of insect damages in control increased with storage from 0.44% to 9.60% while the initial level of insect damage of treated bags remained unchanged. The mass loss due to insect damages of grains was significantly higher (p<0.05) in untreated bags than treated bags. The insect damage was reduced by 9.06 % using Zerofly bags during maize storage. In addition, dead insect bodies were found on outer surface of the insecticide incorporated bags but no live or dead insects were found on untreated bag surface during storage. Mainly rice weevil (Sitophils oryza) and lesser grain borer (Rhysopertha dominica) were found in maize samples of untreated bags and number of insects increased with time. Figures of thousand grains mass and grain hardness of maize seeds of control were significantly lower compared to treated bags (p<0.05). The study revealed that deltamethrin treated bags are appropriate packaging material to protect stored maize from insect infestations.