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Studies on the Intraspecific Larval Interaction in a Laboratory Culture of Plodia Interpunctella (Hubner) (Lepidoptera: Pyralidae) on two Food Media

  • George N. Mbata
Research Article

Abstract

Laboratory studies were carried out to determine the effect of high larval densities of Plodia interpunctella (Hubner) on the development and survival of the moth in two food media. Mortality was found to be higher when reared on groundnuts than on artificial diet. Mortality was between 6.6 and 13.3% when larval densities were below five larvae on 3 g of both groundnuts and the artificial diet in 75 × 25 mm tubes. At higher larval densities (10 or more larvae on 3 g of medium) mortality ranged from 22.5 to 60% on the artificial diet, and on groundnuts it was between 30 and 65%. In both media, development period was prolonged and weights of moths at emergence was lower when larval densities were greater than 10 per tube.

When high densities were experienced between the first and the fourth instars individuals had protracted development, high mortality at larval stage and reduced weights of emerged adults and those subjected to high densities only at the final instars were less significantly affected. It seems that the fourth larval instar is the stage most sensitive to high densities.

Key Words

Plodia larvae density instars mortality 

Résumé

Des études de laboratoire ont été faites pour déterminer l’effet de la concentration intraspécifique larvaire de Plodia interpunctella (Hubner) sur le développement et la survie du lépidoptère dans deux aliments. La mortalité s’est montrée plus élevée dans des arachides que dans une culture lépidoptère. La mortalité était entre 6,6 pour cent et 13,3 pour cent quand la densité larvaire était au-dessous de 5 larves par 3 g d’arachides ou de culture lépidoptère préparée dans des tubes de 75 mm × 25 mm. Avec des densités plus élevées (10 et au-dessus de 10 par 3 g de culture), la mortalité se situait entre 22, 5 pour cent et 60 pour cent pour la culture lépidoptére, et entre 30 pour cent et 65 pour cent pour les arachides. Dans les deux cultures, la période de développement était allongée et le poids des lépidoptères à l’émergence décroissait quand les densités larvaires étaient au-dessus de 10 per tube.

Les larves soumises à la concentration entre le 1er et le 4ème instars ont manifesté un développement prolongé, une mortalité larvaire plus élevée et des poids d’adultes émergents réduits, alors que les larves soumises à la concentration seulement aux derniers instars étaient moins affectées. Il semble que le 4éme instar soit le plus sensible à la concentration.

Mots Cléfs

Plodia larves concentration instars mortalité 

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Copyright information

© ICIPE-ICIPE Science Press 1990

Authors and Affiliations

  • George N. Mbata
    • 1
  1. 1.School of Biological SciencesImo State UniversityOkigweNigeria

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