Abstract

Eureka Mondal*, Sukanta Majumdar and Kaushik Chakraborty

ABSTRACT

Sitophilus oryzae Linn. (Coleoptera: Curculionidae), the rice weevil, is a major stored grain pest of global importance. It affects the stored grains resulting in both qualitative and quantitative lost to a large extent. For investigating the role of S. oryzae as mechanical vector of fungal pathogen, an experiment has carried out. Fresh Swarna mashuri rice grain and a few number of S. oryzae sample were collected from local market and rice mills respectively.Stock culture of the rice weevil was done in glass jar containing non-infested disease free rice grains. Thirty insect samples from the culture vial were inoculated in the separate vial with rice grain showing the sign of fungal infestation.(A) Insects are propagated for two months in that vial and then are transferred to the glass container with fresh grains (B) with no report of fungal contamination and was maintained for another two months. Few drops of the suspension made from the washing of the body surface of the pest from container(B) with distilled water were inoculated randomly in petri-plates containing PDA media that was incubated at 26 ± 2°C for 6-7 days. Two fungal isolates were obtained in pure culture. Morpho-taxonomy reveals that the isolates were Aspergillus flavus and Aspergillus fumigatus respectively. The extent of weight loss was maximum at 60 days after infestation (37.27%) having a consonance with maximum ambient humidity (> 80%). It is thus evicted that apart from grain damage, Sitophilus oryzae also acts as a carrier of harmful Aspergillus sp.