SEASONAL ABUNDANCE OF SPOTTED POD BORER (Maruca sp.) ON EARLY DURATION VARIETY OF PIGEONPEA AND THEIR MANAGEMENT
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Date
2023
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Birsa Agricultural University, Ranchi
Abstract
Pigeonpea, Cajanus cajan, (L.) Millsp, is a shrub legume that is widely grown in tropical and subtropical regions. It is infested by large no. of insect pest limiting the realization of potential yield. Spotted Pod borer, Maruca vitrata, particularly inflicts severe damage on early duration varieties, thereby posing a serious threat to the attainment of the full potential yield of the crop. The present study, "Seasonal Abundance of Spotted Pod Borer (Maruca sp.) on Early Duration Variety of Pigeonpea and their Management" was carried out at the Agriculture Research Farm, Birsa Agricultural University, Ranchi, Jharkhand, during kharif, 2022, to observe the seasonal incidence and population dynamics of Maruca vitrata in relation to important weather parameters, and to evaluate the efficacy of biopesticides for its management in pigeonpea. The study documented the presence of a total of 16 insect species, comprising of 14 insect pests and two natural enemies. The seasonal occurrence of Maruca vitrata persisted from August to November 2022. The population exhibited a significant increase following the onset of 50 per cent flowering and attained its peak in the 40th SMW after which it declined. Two natural enemies, the Ladybird beetle and Spider, were observed during the crop period. In the correlation analysis of weather parameters with the population dynamics of Maruca vitrata, it was found that maximum and minimum temperature, along with mean temperature, had a positive correlation with larval population and webs, as did the minimum relative humidity (RH at 2 pm). However, bright sunshine hours and calculated humid thermal index had a significantly negative correlation with larval population and webs. The efficacy of different biopesticides and a standard insecticidal treatment for the management of Maruca vitrata was studied in a field experiment. The standard treatment (T7) consisting of Chlorantraniliprole 18.5SC, Dimethoate 30EC, and Flubendiamide 480SC, sprayed in sequence showed the highest efficacy, resulting in a significant reduction in the larval population (92.19 per cent) and web count (93.42 per cent), and lower flower parasitisation along with pod and grain damage compared to other treatments. Treatment T1 - Bacillus thuringiensis var. Kurstaki was found to be the most effective biopesticide, resulting in a significant reduction in larval population (78.34 per cent) and web counts (81.85 per cent), lower flower infestation, pod, and grain damage compared to other biopesticides. The cost-benefit analysis revealed that the standard insecticidal treatment (T7) resulted in the highest net profit as well highest B:C ratio, followed by treatment T1(Bacillus thuringiensis var. Kurstaki).