H. K. Jyothi ¹, G. Veeranna ¹, Geetha Bali ²

Affiliations
1 Karnataka State Sericulture Research and Development Institute, Thalaghattapura, Bangalore 560 062, Karnataka, IN
2 Bangalore University, Jnana Bharathi, Bangalore 560056, Karnataka, IN

Abstract

Biology of Dirhinus anthracia Walker was investigated on its natural host, Exorista bombycis Louis at six constant temperatures (10-35°C). The lower threshold for development for male and female was 10.5° and 11°C, respectively. Entire development from egg to adult required 475.05 and 550.96 day degrees, respectively for male and female. Sex ratio was in favour of female at all temperatures except 35°C where a reversal of sex ratio was observed. Reduction in doubling time and generation time was observed as temperature increased.

Keywords

Dirhinus anthracia, Exorista bombycis, Parasitoid, Temperature, Uzi Fly.

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H. K. Jyothi ¹, G. Veeranna ¹, Geetha Bali ²

Affiliations
1 Karnataka State Sericulture Research and Development Institute, Thalghattapura, Bangalore 560062, Karnataka, IN
2 Department of Zoology, Bangalore University, Bangalore 560 056, Karnataka, IN

Abstract

Possibility of low temperature storage of indigenous hymenopteran parasitoids of uzi fly (Exorista bombycis Louis) namely, Nesolynx thymus (Girault), Dirhinus anthracia Walker and Pachycrepoideus veerannai Narendran and AniI at various stages of life cycle, was investigated. Egg, larvae, pupae and adults of all the three parasitoids died when stored at 5 and 1 ODC. However, Dirhinus anthracia and Pachycrepoideus veerannai could be stored for 90 and 45 days, respectively at 15°C without hampering their reproductive potential. With increase in the duration of storage, a reduction in the adult parasitoid longevity and fecundity at ambient temperature was noticed.

Keywords

Dirhinus anthracia, Exorista bombycis, Nesolynx thymus, Pachycrepoideus veerannai, Storage, Uzi Fly.

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K. P. Jayanth ¹, Geetha Bali ²

Affiliations
1 Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Banagalore - 560 089, IN
2 Department of Zoology, Bangalore University, Bangalore, 560 056, IN

Abstract

The neotropical plant Parthenium hysterophorus L. (Asteraceae) is a serious weed of agricultural fields, pastures and waste lands in most parts of India (Krishnamurthy et al., 1977). The mexican beetle Zygogramma bicolorata Pallister (Coleoptera : Chrysomelidae), releases of which were iniitiated in 1984 (Jayanth, 1987), is proving to be a promising biological control agent in and around Bangalore (Jayanth and Geetha Bali, 1990). A number of weedicides have been recommended for the control of, P.hysterophorus in India (Krishnamurthy et al., 1977 ; Muniappa et 01., 1980; Challa, 1987). In situations where chemical methods are preferred, it would be ideal to use weedicides that are least harmful to Z.bicolorata. With this in view, the impact of some commonly used weedicides were tested for their safety to the beetle.

Keywords

Zygogramma bicolorata, Parthenium hysterophorus, Biological Control, Weeds, Effect of Weedicides.

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K. P. Jayanth ¹, Geetha Bali ²

Affiliations
1 Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore, 560089, IN
2 Department of Zoology, Bangalore University, Bangalore, 560056, IN

Abstract

Biological studies were carried out in Bangalore on the leaf feeding chrysomelid beetle, Zygogramma bicolorata Pallister, introduced for biological control trials against the neotropical weed Parthenium hysterophorus L. (Asteraceae). The insect completed its development in 27-29 days at 25.5 ± 1°C. sex ratio was in favour of females, with the males constituting only about 30% of the population. However, males lived longer (l22-271 days) than females (109-198 days). Although females were capable of laying up to 3368 (mean 2590.8) eggs each, only 30-52 % hatched.

Keywords

Zygogramma bicolorata, Biology, Parthenium hysterophorus.

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K. P. Jayanth ¹, Geetha Bali ²

Affiliations
1 Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore - 560 089, IN
2 Department of Zoology, Bangalore University, Bangalore - 560 056, IN

Abstract

Parthenium hysterophorns L. (Asteraceae) is a serious weed of agroecosystems, pastures and waste lands. in India. The Mexican beetle Zygogramma bicorata Pallister (Coleoptera : Chrysomelidae) was released in Bangalore in 1984 for biological control trials against this weed. The insect started building up to damaging population levels from 1988 (Jayanth and Bali, 1990). The present studies were conducted under laboratory conditions to make a critical assessment of the biological control potential of this insect.

Keywords

Zygogramma bicolorata, Parthenium hysterophorus, Biological Control, Intrinsic Rate of Increase.

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