The effectiveness of powdery formulations of long pepper (<em>Piper longum</em> L.) and sweet flag (<em>Acorus calamus</em> L.) to combat the cowpea weevil (<em>Callosobruchus maculatus</em> F.) on stored mung beans

Abstract

The study aimed to evaluate the efficacy of Piper longum L. fruit and Acorus calamus L. rhizome powders in counteracting the Callosobruchus maculatus F. attacks on the mung bean. People frequently consume mung beans; thus, the insecticides, which are used to prevent seeds from infestations by storage pests, should be formulated in such a way that they can be readily removed from grains prior to cooking; for that reason, powdery formulations were selected. Neem plant (Azadirachta indica A.) gum was pulverized and incorporated as adjuvant according to weight. 100 g of mung bean seed lots were individually exposed to powdery formulations of 80%, 90% and 100% of P. longum and A. calamus, respectively and 100% of adjuvant, along with control. Consequently, five pairs of unsexed C. maculatus were introduced into eight treatments, with three replicates and laid out in the Completely Randomized Design. This experiment was designed to evaluate the adult survival, ovipositional capacity, adult emergence of the F1 and F2 generations and developmental period of C. maculatus, and weight loss in mung bean seeds. Simultaneously, qualitative analysis was done to determine the presence of alkaloids, flavonoids, phenol, tannin, steroids, cardiac glycosides, saponin, and anthraquinone phytochemicals in selected botanicals. Data were subjected to the analysis of variance aided by SAS 9.4 version and means were separated by using the Duncan Multiple Range Test at the 5% significance level. According to the statistical analysis, mung beans treated with 100% A. calamus showed no survival of C. maculatus two days after treatment, whereas those treated with 90% A. calamus powdery pesticide showed 3.3% survival. Though minimum cumulative number of eggs was detected in 90% and 100% (11.0, 9.7) of A. calamus treated mung bean seeds, zero progeny development was observed until 60 days; therefore, no weight loss was detected on mung bean seeds. The study concluded that 90 and 100% of the powdery insecticides from A. calamus were efficacious in safeguarding the mung bean from C. maculatus.