Efficacy and cytotoxic potential of deltamethrin, essential oils of Cymbopogon citratus and Cinnamonum camphora and their synergistic combinations against stored product pest, Trogoderma granarium (Everts)

Abstract

Residual film method was followed to analyze the toxicity of deltamethrin, essential oils (EOs) of Cymbopogon citratus and Cinnamonum camphora in separate and form of various combinations against LHR1 and LHR2 populations of fifth instar larvae of Trogoderma granarium. The cytotoxic potential of LC50s of both EOs, deltamethrin and their various combinations was as well investigated. The LHR2 population showed 23.73 fold deltamethrin resistance with respect to LHR1 population. Both EOs had high insecticidal activity than deltamethrin but C. citratus EO was less toxic than C. camphora EO against both populations. Based on strength of synergism and dose reduction index, the order of insecticidal activity of combinations in LHR1 population was: C. citratus EO: deltamethrin < C. camphora EO: deltamethrin < C. citratus EO: C. camphora EO < C. citratus EO: C. camphora EO: deltamethrin. In LHR2 population the order was: C. citratus EO: C. camphora EO < C. citratus EO: deltamethrin < C. camphora EO: deltamethrin < C. citratus EO: C. camphora EO: deltamethrin. Following to exposure of LC50 of each treatment various markers of cytotoxicity viz., haemocyte viability, cell proliferation rate and mitochondrial dehydrogenase activity were decreased significantly with respect to control in both populations. Except for deltamethrin, each treatment significantly increased the lactate dehydrogenase activity. Phenoloxidase activity was reduced significantly in LHR1 population following to exposure of each treatment. Likewise, LHR2 population also showed significantly reduced activity of phenoloxidase following to exposure of each treatment except deltamethrin as it increased the activity. Furthermore, each marker of cytotoxicity was fluctuated in relation to the toxicity of LC50 of treatments and combination contained both EOs and deltamethrin produced highest cytotoxicity. Findings of this study should be used in granaries for the effective control of insecticide resistance in T. granarium1.