Evaluation of larvicidal activity of Panchagavya, against the teak defoliator (<i>Hyblaea puera</i> Cramer) and skeletonizer (<i>Eutectona machaeralis</i> Walker) in a forest plantation

Abstract

Panchagavya is an organic formulation, formed by merging five cow derivatives, such as dung, urine, milk, ghee, and curd, which promotes the growth of plants. The present investigation was aimed to determine the larvicidal efficacy of Panchagavya with varied concentrations against major pests of teak, Tectona grandis, singly, and combined with leaf extract of members of Meliaceae family, and coupled with extract of seaweed, in experimental research plots. Observations on occurrence of pests was also observed periodically and recorded. Treatments include 5% concentration of panchagavya (T1), which serves as a control and Panchagavya combined with varied dosage of other leaf crude extracts of Melia dubia (T2), Melia azedarach (T3), Azadirachta indica (T4), and a seaweed, Sargassum wightii (T5), with a concentration range of 1000-5000 ppm that were used as foliar application. Among the various pests, Hyblaea puera, and Eutectona machaeralis were found to be dominant, and the III instar larval stage were targeted for the management. Maximum larval mortality was observed with exposure to Panchagavya with crude extract of S. wightii, at an appropriate ratio (T5) against teak defoliator, Hyblaea puera. The per cent pest reduction was found to be 65% and 73% in 48 h and 72 h time interval. Similarly, higher level of larval mortality was recorded against skeletonizer (E. machaeralis) where the reduction per cent was recorded as 62% and 71% at 5000 ppm in (T5) within the interval of 48 h and 72 h. Consequently, a distinct individual lethal effect of Panchagavya (T1, control) against both pests was found to be 8%, 24%, and 46% with similar time frames. However, the efficacy of Panchagavya combined with extract of M. dubia, M. azedarach and A. indica exhibited statistically significant ability in larvicidal potential against H. puera. Whereas, treatments like T2, T3, and T4 showed 59, 67, and 62 % of larval mortality of E. machaeralis larva within the period of 72 h. The results of the study affirmed that the synergistic effects of Panchagavya coupled with seaweed extract at appropriate ratio proved to be effective against major pests of teak plantation.