C. KATHIRVELU*, A. S. MALINE, B. ANANADA GANESA RAJA AND T. KAVITHA
Department of Entomology, Faculty of Agriculture, Annamalai University, Annamalainagar-608 002 (Tamil Nadu), India
*(e-mail : ckathirveluau@gmail.com; Mobile : 91 98650 67040)
(Received : April 20, 2020; Accepted : June 18, 2020)
ABSTRACT
An attempt was made to find alternate methods for synthetic fumigants in stored product pest management. Four essential oils, namely, Lantana camara (Lantana) oil, Citronella nardus (Citronella) oil, Cinnamomum
zeylanicum (Cinnamon) oil and Trachyspermmum copicum (Ajwain) oil were selected and evaluated against lesser grain borer Rhyzopertha dominica F. and Red flour beetle Tribolium castaneum H. for their fumigant effect and the weight loss caused by them. The results of the study revealed that C. zeylanicum performed better with lethal concentration (LC50) effect of 25.40, 46.25 and 9.47 µl in minimal period of exposure i. e.
at 12 h of treatment against adults of R. dominica, adults and larvae of T. castaneum, respectively. During the maximum period of exposure i. e. at 72 h, T. copicum was noticed to be highest with 6.26 µl in causing
mortality (LC50) against adults of R. dominica, whereas C. zeylanicum essential oil was found maintaining better efficacy against adults and larvae of T. castaneum with a LC50 of 4.40 and 2.48 µl, respectively. In evaluating the damage caused by the target insects after the treatment of 60 days, C. zeylanicum excelled with the least loss of 8.34 % in weight of flour against T. castaneum. However, T. copicum was detected to be better with 10.32% weight loss of grains against R. dominica. The fumigant toxicity bioassay revealed that as the exposure period increased mortality of test insects also found increased i. e. exposure period was directly proportional to mortality of insects.
Key words : Coleoptera, essential oils, fumigant toxicity, stored product pests, volatiles