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Entomophaga

, Volume 39, Issue 1, pp 71–83 | Cite as

Conservation of two predator species for biological control ofChrysophtharta bimaculata (Col.: Chrysomelidae) in tasmanian forests

  • R. K. Mensah
  • J. L. Madden
Article

Abstract

Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae) is a major defoliator of regeneration eucalypt trees in Tasmania causing a significant reduction in height and diameter increment of trees which reduces wood volume per hectare. A study to conserve and enhance the efficiency of coccinellid species chieflyCleobora mellyi (Mulsant) (Coleoptera: Coccinellidae), and the cantharid,Chauliognathus pulchellus (Macleay) (Coleoptera: Cantharidae), for the biological control ofC. bimaculata was conducted in young regeneration forests in southern Tasmania from 1991–92. Cantharid adults and coccinellid adults and larvae feed onC. bimaculata eggs and, to a lesser extent, young larvae. The study found that coccinellids were more active throughout the egg and early (1st and 2nd) stage ofC. bimaculata. The cantharid, however was active only during the egg stage of the prey and then disappeared from the plantation. The coccinellids were therefore the most useful predators, but their population declined when the prey reached the 3rd and 4th stages. As shortage of food may account for this decline, supplementary food was provided in the form of sucrose sprays or sugar granules at a feeding station. This resulted in the retention of both predators and particularly the coccinellids and enhanced their efficacy.

Key-Words

biological control cantharid supplementary food coccinellids 

Résumé

Chrysophtharta bimaculata Olivier (Col. Chrysomelidae) est un défoliateur important des régénérations d'eucalyptus en Tasmanie: il cause une forte réduction de l'accroissement en hauteur et en diamètre des arbres, réduisant ainsi le cubage de bois produit à l'hectare. En 1991 et 1992, une étude pour conserver et accroître l'efficacité de coccinelles, principalementCleobora mellyi Mulsant (Col.: Coccinellidae), et d'une cantharide,Chauliognathus pulchellus (Macleay) (Col.: Cantharidae) comme agents de lutte biologique, a été faite dans les jeunes peuplements forestiers de Tasmanie du sud pour la lutte biologique deC. bimaculata. Les cantharides adultes et les adultes et larves de coccinelles se nourrissent des œufs deC. bimaculata et à un degré moindre, des jeunes larves. L'activité des coccinelles était la plus importante pendant le stade œuf et les premier et deuxième stades larvaires deC. bimaculata. Les cantharides n'étaient actives que durant le stade œuf de la proie puis disparaissaient de la parcelle. Les coccinelles étaient donc les prédateurs les plus utiles, mais leur population diminuait lorsque la proie atteignait les 3e et 4e stades larvaires. Comme le manque de nourriture pouvait être à l'origine de leur diminution, un complément de nourriture a été fourni sous forme de pulvérisation de saccharose ou de granules de sucre déposées à une station de nourrissage. Ceci a provoqué le maintien des populations des deux prédateurs, particulièrement des coccinelles, et a augmenté leur efficacité.

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Copyright information

© Lavoisier Abonnements 1994

Authors and Affiliations

  • R. K. Mensah
    • 1
  • J. L. Madden
    • 1
  1. 1.Department of Agricultural ScienceUniversity of TasmaniaHobartAustralia

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