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Interactions between the endophagous parasitoid Epidinocarsis lopezi and its host, Phenacoccus manihoti

Published online by Cambridge University Press:  19 September 2011

P. Neuenschwander
Affiliation:
International Institute of Tropical Agriculture, Oyo Road, PMB 5320, Ibadan, Nigeria
D. Sullivan
Affiliation:
Visiting scientist from Fordham University, Bronx, New York
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Abstract

Epidinocarsis lopezi proved to be an efficient biological control agent of the cassava mealybug (CM), Phenacoccus manihoti, despite apparently low parasitization rates. Laboratory experiments indicated that its killing power at higher temperatures was two to three times higher than the per cent mummy formation suggested. Following an attack by an E. lopezi female some CM hosts were killed through host feeding and some through successful development of the parasitoid larva, processes which both benefit the parasitoid. If the host was found unsuitable, no egg was laid, and the CM survived the attack. Other CM died from the wasp attack without forming a mummy. This mortality is attributed to mutilation and unsuccessful larval development of E. lopezi. Most ovipositions induced a defence reaction by the host that lead to melanization. This process involved mainly wound tissue, sometimes partial encapsulation of the tail end of the parasitoid larva, and infrequently complete and fatal encapsulation of the parasitoid larva.

Résumé

Malgré un taux de parasitisme apparemment faible, Epidinocarsis lopezi s'est révélé un agent de lutte biologique efficace contre la cochenille du manioc, Phenacoccus manihoti. Les expériences de laboratoire ont montré que son pouvoir destructif, en présence de températures élevées, était deux à trois fois supérieur à ce qu'aurait laisser prévoir le pourcentage de momies. L'attaque de E. lopezi entraîne la mort de la cochenille hôte par ingestion de l'hôte ou par le développement des larves du parasitoïde, deux mécanismes favorables au parasitoïde. On n'observe aucune ponte dans un hôte inapproprié; la cochenille survit à l'attaque. Certaines cochenilles ont succombé à l'attaque de la guêpe sans toutefois former de momie. La mortalité est alors imputable à la mutilation et à l'interruption du développement larvaire de E. lopezi. Dans la plupart des cas, l'introduction de l'oeuf suscite une réaction de défense de la part de l'hôte se traduisant par la mélanisation, phénomène qui donne le plus souvent lieu à des déchirures cellulaires, occasionnellement à l'encapsulation partielle de la portion caudale des larves du parasitoïde et, dans des cas plus rares, à l'encapsulation totale et mortelle de la larve.

Type
Symposium XI: Africa-wide Biological Control Programme of Cassava Pests
Copyright
Copyright © ICIPE 1987

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References

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