K. I. Singh ¹, C. H. Singh ¹, M. P. Singh ¹, M. K. Gupta ¹

Affiliations
1 Department of Entomology, College of Agriculture, Central Agricultural University, Imphal 795004, Manipur, IN

Abstract

The predation efficiency of five species of coccinellids, namely, Coelophora biplagiata (Swartz), Coccinella transversalis F., Menochilus sexmaculatus (F.), Cryptolaemus montrouzieri Mulsant, and Chilocorus nigrita (F.), against cowpea aphid, Aphis craccivora Koch, was evaluated in the laboratory. Maximum consumption of A. craccivora (65.20 ± 0.59 to 214.60 ± 2.60) was observed in C. biplagiata released under various predator densities, whereas C. montrouzieri consumed the minimum numbers (19.40 ± 0.36 to 84.60 ± 0.73). C. biplagiata was closely followed by M. sexmaculatus and C. transversalis. It was also observed that C. biplagiata, M. sexmaculata and C. transversalis exhibited higher predation efficiency with a mean aphid consumption of 43.60 ± 0.46 to 485.80 ± 5.18, 41.20 ± 0.33 to 377.00 ± 3.35 and 40.60 ± 0.96 to 370.00 ± 3.74, respectively, under different prey densities of 45 to 720. When C. biplagiata was released, significantly lowest aphid population (23.06) was recorded, followed by M. sexmaculatus (35.26), C. transversalis (43.00) and C. nigrita (49.13) as against unreleased control (191.86). The highest aphid population (54.26) was recorded in the treatment where C. montrouzieri released.

Keywords

Aphis craccivora, Cowpea, Feeding Efficiency and Predaceous Coccinellids.

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K. I. Singh ¹, S. K. Jalali ², R. J. Rabindra ², N. S. Rao ², Y. Lalitha ²

Affiliations
1 Department of Entomology, College of Agriculture, Central Agricultural University, lmphul 795 004, Manipur, IN
2 Project Directorate of Biological Control (lCAR), Post Bag no. 2491, Bellary Road, Hebbal, Bangalore 560 024, Karnataka, IN

Abstract

The optimum release dosage of Trichogrammatoidea bactrae Nagaraja and its comparative efficacy alone and in combination with dichlorvos against diamondback moth (DBl\1), Plutella xylostella (Linnaeus) on cabbage was worked out. Results of the study on the percentage parasitization under different host-parasitoid ratios revealed that the maximum DBM egg parasitization (83.0%) was recorded in the ratio 100 (eggs): 5 (females), which was on par with other higher ratios of 100:10 to 100:20. The release of T. bactrae twice (2 and 5 days after DBM moth release) proved as the most effective treatment in significantly reducing the larval population (4.89 larvae per plant) in comparison to two sprays of dichlorvos (0.05%) (14.54 larvae per plant). The results indicated the efficacy of T. bactrae in suppressing DBM on cabbage and calls for further evaluation in field trials.

Keywords

Cabbage, Dichlorvos, Efficacy, Plutella xylostella, Trichogrammatoidea bactrae.

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K. I. Singh ¹, A. Debbarma ¹, H. R. Singh ¹

Affiliations
1 Department of Entomology, College of Agriculture, Central Agricultural University, Imphal - 795004, Manipur, IN

Abstract

A field trial was experimented during Rabi, 2014-15 at the Vegetable Research Farm of College of Agriculture, Central Agricultural University, Imphal to evaluate certain microbial pesticides against the diamond back moth, Plutella xylostella Linnaeus and the cabbage butterfly, Pieris brassicae Linnaeus and their effect on the population of lady bird beetle, Coccinella septempunctata Linnaeus in cabbage -crop-ecosystem of Manipur. The results on the efficacy of insecticides against P. xylostella and P. brassicae revealed that all the insecticidal treatments resulted in significantly suppression of both the pests' incidence. However, bioasp (Bacillus thuringiensis var. kurstaki) @ 1000 g ha^-1 was the most effective insecticide against P. xylostella with a record of minimum mean leaf damage of 13.32 per cent as against 69.18% in untreated control, closely followed by spinosad 2.5 SC applied @ 500 ml ha^-1(14.22% LD) which did not differ significantly from each other. Against P. brassicae spinosad 2.5 SC registered significantly the lowest mean leaf damage of 24.30 per cent as against 87.38% in untreated check, closely followed by myco-jaal 10 SC (Beauveria bassiana) with a record of 26.59 per cent leaf damage but, differed significantly between them. The highest mean leaf damage incidence (37.47% LD) was noticed in the plots treated with brigade (Vertcillium lecanii) applied @ 1250 g ha^-1. The results on toxic effect of insecticides on the population of C. septempunctata revealed that bioasp (B. thuringiensis var. kurstaki) @ 1000 g ha^-1 proved to be the safest insecticide with significantly highest population of 1.99/ 5 plants as against 3.04/5 plants recorded in untreated control, followed by myco-jaal 10 SC (B. bassiana) @ 500 ml ha^-1 (1.61 beetles/ 5 plants) and spinosad 2.5 SC @ 500 ml ha^-1 (1.51 beetles/ 5 plants) which did not differ significantly from each other. The lowest population C. septempunctata (0.55/plants) was observed in the malathion 50 EC @ 500 ml ha^-1 treated plots. The highest mean cabbage yield (24.77 t ha^-1) was harvested from the plots treated with spinosad 2.5 SC with the maximum yield increase over control of 9.37 t ha^-1 which showed non significant difference with the plots of bioasp (B. thuringiensis var. kurstaki (23.70 t ha^-1) with its yield increase over control of 8.30 t ha^-1, whereas verticel (V. lecanii) @ 1000 g ha^-1 treated plots accrued significantly lowest cabbage yield of 19.27 t ha^-1 with a record of lowest yield increase over control of 3.87 t ha^-1. The avoidable yield loss was computed to be 37.82 per cent in the untreated control plots. Application of insecticides resulted in reduction of the mean avoidable loss, which ranged between 4.32 and 22.21 per cent in different insecticidal treatments, the lowest being in bioasp (B. thuringiensis var. kurstaki) and highest in verticel (V. lecanii). The net profit of the insecticidal treatments varied from Rs. 17860.60 (verticel) to Rs. 45621.60 (spinosad) with the cost : benefit ratios ranging between 1:11.99 and 1:43.09, the minimum and maximum being with verticel and myco-jaal 10 SC, respectively.

Keywords

Cabbage, Coccinella septempunctata, Field Evaluation, Microbials, Plutella xylostella, Pieris brassicae.

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K. I. SINGH ¹, M. BASAR ¹, S. M. HALDHAR ¹

Affiliations
1 Department of Entomology, College of Agriculture, Central Agricultural University, Imphal – 795004, Manipur, India ., IN

Abstract

The field experiments were conducted to study the bio-efficacy of microbial insecticides against Pieris brassicae Linnaeus in cabbage crop var. “Green Hero” in NEH region of India. The pooled data of two years indicated that Metarhizium anisopliae @ 1500 g/ha proved the most effective treatment in reducing the incidence of P. brassicae with a minimum mean leaf damage of 49.93 per cent as against 67.57 per cent in untreated control followed by Beauveria bassiana 10 SC @ 1000 ml ha-1 and M. anisopliae @ 1000 g ha-1 with a record of lower mean leaf damage of 51.68 and 51.85 per cent, respectively. The treatment M. anisopliae @ 1500 g ha-1 recorded maximum cabbage yield of 17.09 t ha-1 , followed by B. bassiana 10 SC @ 1000 ml ha-1 treated plots (15.19 t ha-1) and M. anisopliae @ 1000 g ha-1 (15.02 t ha-1). The minimum yield (12.84 t ha-1) was obtained from the plots treated with Dichlorvos 76 SL @ 500 ml with an increased yield of 3.09 t ha-1 over control, but, did not differ significantly from rest of the treatments. The extent of avoidable yield loss due to the incidence of P. brassicae was estimated to be 45.98 per cent in untreated control which was reduced to 9.41-28.86 per cent in treated plots. Minimum avoidable yield loss being recorded in B. bassiana 10 SC @ 1000 ml ha-1 and maximum avoidable yield loss in Dichlorvos 76 SL @ 500 ml ha-1 treatments. The net profit of the treatments varied from Rs. 28,350.00 (Dichlorvos 76 SL @ 500 ml ha-1) to Rs. 77,150.00 (M. anisopliae @ 1500 gm ha1 ) with the cost-benefit ratio of 1:11.12 to 1:13.19 in the treatments. Beauveria bassiana 10 SC @ 1000 ml ha-1 gave the highest benefit-cost ratio of 1:13.19, while the lowest was in Dichlorvos 76 SL @ 500 ml ha-1 with 1:11.12 .

Keywords

Bio-efficacy, cabbage butterfly, microbial control, Pieris brassicae .

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