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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730
EISSN: 2072-6589
Vol. 6, No. 1, 1998, pp. 49-59
Bioline Code: cs98006
Full paper language: English
Document type: Research Article
Document available free of charge

African Crop Science Journal, Vol. 6, No. 1, 1998, pp. 49-59

 fr
Ekesi, S.; Maniania, N.K. & Onu, I.

Résumé

Des etudes ont ete conduites au laboratoire pour etudier le mecanisme de resistance de deux varietes de niebe (Vigna unguiculata L. Walp), ICV 8 at IT84S-2246, a l'egard du thrips des fleurs de niebe, Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae). Une mortalite elevee des stades larvaires ainsi qu'un long developpement larvaire ont ete observes avec la variete ICV 8, montrant ainisi la presence des mecanismes antibiotiques de resistance. La longevite des adultes et le taux d'oviposition des insectes nourris au pollen de la variete ICV 8 etaient considerablement reduits. Les poids moyen des larves et des pupes etait egalement peu eleve avec cette variete; toutefois, le poids des adultes n'etait pas affecte. Avec la variete IT84S-2246, la mortalite etait peu elevee, tandis que le taux de developpement larvaire etait normal, indiquant ainsi l'absence des mecanismes antibiotiques. Cependant, un test a double choix avec les fluers de niebe et un essai dan un olfactometre, ont revele que la variete IT84S-2246 etait la moins preferee, indiquant ainsi que l'antixenose est le mecanisme de resistance pour cette variete.

Mots Clés
Megalurothrips sjostedti, resistance, olfactometre, Vigna unguiculata

 
 en Antibiosis and antixenosis of two cowpea varieties to the legume flower thrips
Ekesi, S.; Maniania, N.K. & Onu, I.

Abstract

Laboratory investigations were conducted to study the mechanisms of resistance of two cowpea (Vigna unguiculata L. Walp) varieties, ICV 8 and IT84S-2246 to the legume flower thrips, Megalurothrips sjostedti (Trybom) [Thysanoptera: Thripidae]. High mortality of larval stages and slower developmental rates on ICV 8, indicated presence of antibiotic mechanisms of resistance. Adult longevity and oviposition rates of thrips fed on pollen of ICV 8 were greatly reduced. Mean larval and pupal weights were also low on this variety but adult weight was not affected. Mortality rates on IT84S-2246 was low and developmental rates was normal, indicating an absence of antibiotic mechanisms. However, a choice experiment using cowpea flowers, and olfactometer assessment, showed that IT84S-2246 was the least preferred variety, indicating evidence of antixension as the mechanism of resistance in this variety.

Keywords
Megalurothrips sjostedti, resistance, olfactometer, Vigna unguiculata

 
© Copyright 1998 - African Crop Science Society

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