Abstract
Objectives: To develop a method to replace the usage of synthetic fumigants in stored product pest management. Methodology: For this purpose, we employed four plant based essential oils namely, Lantana camara (Lantana) oil, Citronella nardus (Citronella) oil, Cinnamomum zeylanicum (Cinnamon) oil and Trachyspermmum copicum (Ajwain) oil and evaluated against pulse beetle, Callosobruchus chinensis L., and rice weevil, Sitophilus oryzae L., for their fumigant toxicity and the weight loss caused by them. The oils of Lantana and Citronella were extracted from leaves, Cinnamon and Ajwain from barks and seeds respectively. Findings: Among the essential oils tested for fumigant toxicity, C. zeylanicum performed better with Lethal Concentration (LC50) of 23.16 and 21.91ml in minimal period of exposure i.e. at 12 h of treatment and found effective against adults of test insects viz., C. chinensis, and S. oryzae respectively. During the maximum period of exposure i.e. at 72 h. the fumigation efficacy of T. copicum was noticed to be the highest (3.43 ml) against adults of C. chinensis whereas C. zeylanicum was found better against S. oryzae (6.19ml). The minimum loss of pulse grains was observed in C. zeylanicum treated at 60 % of 24 h LC50 ; with 7.41 % weight loss. The minimum weight loss was noticed in C. zeylanicum about 60 % of 24 h LC50 with 9.68 per cent against S. oryzae. The fumigant toxicity bioassay revealed that as the exposure period increases, mortality of test insects also found increased i.e. exposure period directly proportional to mortality of insects. Keywords: Coleoptera; essential oils; fumigant toxicity; stored product pests; volatiles
Highlights
The food requirement of an increasing human population remains a major global issue
The fumigant effect of essential oils at different exposure periods were tested against the adult beetles of C. chinensis and Lethal Concentration (LC50) along with Upper and Lower Confidence Limit (UCL and LCL 95 %) were obtained and the results presented in Table 1 as μl/ lit
Among the essential oils tested, C. zeylanicum performed better at 12 h of exposure period followed by L. camara, T. copicum and least performance with C. nardus, their 12 h LC50 values were 23.16 μl, 25.23 μl, 30.80 μl and 33.89 μl respectively
Summary
More than one third of food is lost or wasted during post harvest operations. Reducing the post harvest losses, a concrete solution will be to increase the availability of Kathirvelu et al / Indian Journal of Science and Technology 2020;13(25):2575–2581 food, reduce damage on natural resources, eliminate hunger and improve farmers’ livelihoods. Cereal grains are the staple food in most of the developing nations and it account for maximum post harvest losses. Storage losses have been estimated as 14 million tonnes of food grain and worth of |7,000 crore every year in India, out of which insects alone account for nearly |1,300 crores. Out of all the post harvest losses, storage alone 6.58 %, in this insect alone account for 2.0 to 4.2 % followed by rodents (2.50 %), Birds (0.85 %) and moisture (0.68 %) [3]
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