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Distribution patterns, sample-size and sampling Earias spp. on cotton in Ludhiana (Punjab)*

Published online by Cambridge University Press:  19 September 2011

A. K. Chakravarthy
A. K. Chakravarthy
Affiliation:
Department of Entomology, Punjab Agricultural University, Ludhiana 141004, India
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Abstract

Eggs and larvae of the bollworms Earias spp. followed a uniform distribution on G 27, LD 133, LD 230 (Arboreum) and F 414 (hirsutum) cotton varieties in Ludhiana (Punjab). Clump distribution of Earias eggs and larvae on the four cotton varieties may result from environmental heterogeneity. Although Earias gravid females laid maximum eggs at the top (41–50 cm) plant canopy mostly, examination of the whole length of the plants is suggested for sampling Earias on the four varieties.

Sample sizes of 10 plants in arboreum and seven in the hirsutum variety resulted in reliable estimates of population at 5% risk level. Injured fruiting bodies and larval numbers were significantly and positively correlated.

Résumé

Les oeufs des larves des vers Earias spp. ont adopté une distribution uniforme sur les variétés de cotton G27, LD133, LD230, et F414 à Ludhiana (Punjab). Les oeufs et les larves ont atteint leurs nombres maximaux une fois que la plante atteignait sa hauteur maximale (41–50 cm). Quand les plantes étaient âgées de 110 jours, on a fait des prélèvements sur dix plantes pour garantir une estimation fiable de Earias spp. sur les quatre variétés de cotton. Il y avait une corrélation significative (r = 0,5807) au niveau de 5% entre le pourcentage de dégâts causés par Earias sur les structures fruitières et leurs nombres larvaires. Par conśequent, l'utilisation du pourcentage de structures fruitières endommagées pour le prélèvement des échantillons d'Earias est suggéré.

Keywords

Spatial patternsample sizecottonEarias spp.LudhianaModèle spatialgrandeur de l'échantilloncottonEarias sppLudhiana
Type
Research Articles
Information
International Journal of Tropical Insect Science , Volume 6 , Issue 4 , August 1985 , pp. 517 - 520
Copyright
Copyright © ICIPE 1985

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References

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