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Studies on Biology, Host Instar Preference and Preliminary Evaluation of Apanteles Sp. and Meteorus Sp. as Parasitoids on Spilarctia Obliqua (walker)

A.T.M.F.Islam
Institute of Food and Radiation Biology Atomic Energy Research Establishment G.P.O. Box No. 3787, Dhaka-1000, Bangladesh

S. lslam
Institute of Food and Radiation Biology Atomic Energy Research Establishment G.P.O. Box No. 3787, Dhaka-1000, Bangladesh

M.S. Alam
Institute of Food and Radiation Biology Atomic Energy Research Establishment G.P.O. Box No. 3787, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

Experiments were conducted on the life cycle, host instar preference and parasitization efficiency of two parasitoids, Apanteles sp. and Meteorus sp. on the larvae of Spilarctia (=Spilosoma) obliqua. It was found that the mean durations from egg to larva of Apanteles sp. and Meteorus sp. were 7.9±1.07 and 9.5±0.61 days, prepupal period 0.25±0.07 and 0.23±0.05 days and pupal period was 5.10±1.02 and 6.60±0.68 days respectively in second instar of S. obliqua larvae. The adult male and female longevity recorded 3.35±0.49 and 3.75±0.64 days for Apanteles and 5.95±0.94 and 6.50±0.69 days of Meteorus parasitoid. The eggs laid by the unmated female parasitoids produced only male progeny, while mated female produced male and female progeny in a ratio of 1:1.52 and 1:1.87. Parasitism of both species of parasitoids consistently involved only in second and third instar larvae. The mean parasitism rate of mated and unmated Apanteles was 43.0 and 37.0% in second instar larvae and the rate decreased to 38.0 and 34.0 in third instar host larvae. The parasitism rate of Meteorus from mated and unmated was 50.0 and 48.0% in second instar larvae while 44.0 and 38.0% for third instar larvae. Results also indicated that the development of S. obliqua were found to be arrested following parasitization of Apanteles sp. and Meteorus sp. Moulting of Spilarctia obliqua was suppressed during parasitoids emergence.

Keywords: Biology, Preference, Evaluation, Apanteles sp., Meteorus sp., Spilarctia obliqua

Location: Institute of Food and Radiation Biology Atomic Energy Research Establishment

Start Date: 00-06-2001

End Date: 00-12-2001

Program Area: Pest Management

Commodity: Jute

Objectives:

To know the biology, host instar preference and parasitization efficiency of Apanteles sp. and Meteorus sp. on Spilarctia obliqua.

Methodology:

Small scale cultures of parasitoids, Apanteles sp. and Meteorus sp. were done using second and third instar larvae of S. obliqua as host collected from the jute field. They were reared in Petri dishes (15 cm dia x 1.5 cm depth) in the laboratory at 28.0±0.5°C temperature and 76.5±3.5% relative humidity. The laboratory cultures were maintained so that both parasitoid larvae may come out due to natural parasitisation of the host in the field. Host larvae were transferred regularly to new Petri dishes with fresh jute leaves and reared to fifth instar. Meanwhile parasitoid larvae came out from the host larvae and pupated. Pupae were then transferred in separate jelly jar and kept undisturbed till adult emergence. The mouth of jelly jar was covered with thin cloth tying with a rubber band. Afterwards, emerged adults were sexed and confined in pairs in a separate jar. Mated female parasitoids were separated from males and released on second and third instar host larvae in jelly jar individually for oviposition. Honey solution at 3:1 (water : honey) was supplied in cotton as food to adult parasitoids. The mouth of the jars were covered as before. Parasitized larvae were reared like before and the cultures continued till the end of the experiment.

Source of Information: Bangladesh J. Agril. Sci. 30(2): 233-240, July, 2003

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The result indicated that the parasitized host larvae were smaller in size and longer .in developmental period than control. The arrested development of the host continued during the lengthy post emergence period before host death. It was found that the parasitized larvae consumed less food than unparasitized host larvae, which might be responsible for the physiological state of the parasitized larvae. The process of moulting and pupation might depend on the hormonal activities and accumulation of certain nutritive reserve. As parasitized larvae consumed less food, it could be ascertained that the physiological needs of them were low and they were starved due to physical viability to accumulate nutritive reserved in the body. Similar developmental arrestment occurs in a wide range of parasitized insects, including habitual host of other Apanteles sp. (Smith and Smilowitz, 1976). Beckage (1982) observed the larvae of Manduca sexta parasitized by Apanteles smerinthi indicated that parasftism induced only partial developmental arrestment.

Knowledge Management: Journal