Efficacy of food-grade diatomaceous earth as grain protection against Rhyzopertha Dominica - lesser grain borer in stored chickpea under tropical conditions

Abstract

Insects are the major cause of the storage losses in grains [1]. According to recent studies, the loss of grains during storage under conventional warehousing circumstances in Sri Lanka, like in other tropical nations, is about 4-6 %, with insect attacks accounting for 80 % of the total. DEs are inert dust by origin and consist of the fossils of phytoplankton (diatoms) which are mainly composed of amorphous hydrated silicates [2]. When insects come into contact with the DE particles, the waxy fat, and lipids are absorbed from their cuticles, resulting in water loss dehydration, and death [3]. DEs are of extremely low toxicity to mammals [4]. The lesser grain borer is a serious pest of stored grain worldwide [5]. Several reports showed that the lesser grain borer can be controlled using DE [6]. However, according to Stathers et al, (2002) the main problem limiting their use as a grain protectant is the lack of information on their efficacy under smallholder farming conditions [5]. Thus, there is a need to assess the efficacy of the food-grade DE for the controlling of insect pests in pulses. The efficacy of the food-grade DE will be assessed on chickpeas for up to 9 weeks during the 2021 grain storage season from March to May. Farmers find it difficult to store these grains since they are highly susceptible to insect storage pests. Determination of the most appropriate application rates and the residual protection offered by these DEs is also important.