Plant Essential Oils Against Pulse Beetle, Callosobruchus chinensis (Coleoptera: Chrysomelidae) Management

Abstract

Background: Pulse beetle, Callosobruchus chinensis (L.), is a major insect pest of stored legume grains and has developed resistance to a broad range of chemical insecticides. Plant essential oils (PEOs) show potential in management of stored-product pests. However, there are limited research about their use in Nepal. Six plant essential oils (PEOs) were tested against pulse beetles considering their fumigation toxicity and ovicidal actions including post-treatment legume grain quality. Methods: Two doses (100 μl and 200 μl for fumigant toxicity and 10 μl and 20 μl for ovicidal actions) of each of the essential oils tested in laboratory condition in a completely randomized design with four replications. Result: The descending order of fumigant toxicity to adult pulse beetle was observed at four days of fumigation: citronella greater than prickly ash greater than artemisia greater than sweet flag greater than tea tree greater than mint. The lowest grain damage and grain moisture content were in citronella-treated units and the highest in control. The fumigation did not impair grain germination. The highest ovicidal rate was in citronella-treated units (96.25±2.06%) followed by prickly ash, sweet flag, mint, tea tree and the lowest in artemisia EO treated unit (16.25±2.45%). This research strongly suggests that citronella, prickly ash and artemisia EOs are alternative to chemical insecticides in pulse beetle management at stored conditions.