DEVELOPMENT AND STANDARDIZATION OF BLACKGRAM BASED SEMI-SYNTHETIC DIET FOR SPOTTED POD BORER, Maruca vitrata (Geyer) (CRAMBIDAE: LEPIDOPTERA) AND ITS MANAGEMENT WITH BIOPESTICIDES
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Date
2022-08-10
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guntur
Abstract
The present investigation was carried out at the Department of Entomology, Agricultural College, Bapatla during the period 2020-21 on ―Development and Standardization of Blackgram based Semi-Synthetic Diet for Spotted Pod Borer, Maruca vitrata (Geyer) (Crambidae: Lepidoptera) and its Management with Biopesticides‖.
To mass rear M. vitrata under laboratory conditions, a study was carried out to develop a blackgram based semi-synthetic diet (D-B). Comparison of several biological, reproductive and digestive parameters for three successive generations of M. vitrata reared on four different semi-synthetic diets viz., D-J, D-JR, D-NEW and blackgram based semi-synthetic diet (D-B) along with blackgram natural diet was successfully attempted.
Larvae fed on blackgram based semi-synthetic diet (D-B) recorded the shortest developmental time (29.37 days), the highest food consumption (64.21 mg) and fecal production (20.83 mg) resulting in the maximum larval and pupal weights (48.46 and 47.11 mg, respectively). The insects fed on D-NEW and blackgram natural diet recorded the longest developmental period (32.90 and 34.48 days) with minimum larval weights (44.03 and 48.64 mg) and pupal weights (40.39 and 49.43 mg), respectively.
The highest per cent pupation (82.53), adult emergence (78.22), larval (6.50) and pupal growth indices (12.86) were recorded on larvae fed with blackgram based semi synthetic diet (D-B). The highest sex ratio (1.81) and fecundity (43.94 eggs) were recorded on blackgram semi-synthetic diet (D-B). The highest Relative Consumption Rate (0.23 gg-1day-1), Relative Growth Rate (0.084 gg-1day1), Relative Metabolic Rate (0.073 gg-1day-1), Approximate Digestibility (67.49%) and Metabolic Costs (46.51%) lowest Efficiency of Conversion of Ingested Food (36.09%) and Efficiency of Conversion of Digested Food (53.49%) were recorded on blackgram semi-synthetic diet (D-B).
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Laboratory experiments were conducted to test the efficacy of native Bt isolates viz., 16, 49, 51, 52, 55, 493.A bioassay was carried out on third instar larvae of M. vitrata using a blackgram flower dip bioassay method and compared with a reference strain, HD-1. The mean per cent mortality of M. vitrata larvae with native Bt isolates ranged between 60.00 and 93.33 per cent.
Among the seven treatments tested, Bt isolate HD-1 was found to be highly effective against third instar larvae with LC50 and LC90 values of 3.18 × 107 and 3.62 × 1011 CFU, respectively with LT50 and LT90 values of 108.15 and 168.84 hpi, respectively. Among the native Bt isolates the lethal action regarding LT50 was recorded by Bt isolate 493 followed by Bt isolates 16, 51, 52, 55 and 49 with 112.05, 117.96, 130.14, 134.33, 135.30 and 150.44 hpi, respectively and the LC50 of 1.53× 108, 3.64 × 108, 9.15 × 109, 3.09 × 1010,1.30 × 1010 and 5.57× 1010 CFU ml-1, respectively. Similarly, LT90 was recorded with 184.01, 206.15, 234.22, 239.71, 240.46, and 272.88hpi, respectively and the LC90 of 1.99× 1012, 9.05 × 1013, 2.32 × 1015, 9.24 × 1015, 5.39 × 1015, and 1.60 × 1017 CFU ml-1, respectively.
Field efficiency of nine microbial bioinsecticides (Bt isolates16, 49, 51, 52, 55, 493, HD-1, Dipel, M. anisopliae) and spinosad 45 SC were evaluated against M. vitrata infesting blackgram during rabi season of 2021. The results revealed that spinosad 45 SC, Dipel, M. anisopliae, Bt isolate HD-1and Bt isolate 493 were found to be the most effective in reducing the larval population and also in per cent reduction of the bud, flower and pod damage of blackgram. The maximum increase of seed yield (166 kg) of blackgram over control was recorded in spinosad 45 SC.
The next effective treatments were Dipel, M. anisopliae, Bt isolate HD-1and Bt isolate 493. The treatments of spinosad 45 SC and Dipel gave the highest ICBR of 1:7.24 and 1:6.75, respectively followed by M. anisopliae (1:6.24) Bt isolate HD-1 (1:5.62) and Bt isolate 493 (1:4.70). Thus, three sprays of microbial bioinsecticides, at the time of bud initiation, flowering and pod developmental growth stages were found efficacious on the field management of M. vitrata on blackgram with higher yields.
Description
DEVELOPMENT AND STANDARDIZATION OF BLACKGRAM BASED SEMI-SYNTHETIC DIET FOR SPOTTED POD BORER, Maruca vitrata (Geyer) (CRAMBIDAE: LEPIDOPTERA) AND ITS MANAGEMENT WITH BIOPESTICIDES