Abstract
Anatomical features of cowpea (Vigna unguiculata) associated with stem and pod wall resistance to the legume pod borer, Manica testulalis, were studied. The anatomical microenvironment of the area immediately post the stem epidermis seems to impose severe limitation to larval movement and feeding within the tissue. Coiienchyma cells in both 21-day old TVu 946 and IT82D-716 stems form a network of closely knit interlocking cells with a few intercellular spaces. Significant differences (P <0.05) were observed in the distance between the epidermis and coiienchyma cells of the slightly raised (convex) and concave portions of TVu 946 and IT82D-716 stems. TVu 946 had a smaller stem diameter than IT82D-716 stem. Distance between epicarp and mesocarp tissues of 7-day old TVu 946 and IT82D-716 pod wall did not show any significant difference. Similarity in cell and tissue arrangement and the absence of strengthening tissues in pod wall could be some of the most important constraints responsible for their vulnerability to larval damage.
Stem anatomy is considered to be an important factor in stem resistance to M. testulalis, but this does not appear to be the case in pod wall resistance.
Résumé
Les caractèristiques anatomiques du nièbé (Vigna unguiculata) associées à la résistance de la tige et de la gousse aux foreuses Mantea testulalis ont été étudiées. Le microenvironnement anatomique de la partie qui vient immédiatement après l’èpiderme de la tige semble entraver sérieusement tout mouvement et alimentation larvaires dans les tissus. Les cellules collenchymateuses des tiges de TVu 946 et IT82D-716, âgées de 21 jours, forment un dense réseau de cellules enchevêtrées au sein duquel l’on trouve quelques espaces intercellulaires. Des différences significatives (P <0.05) ont été observées dans la zone située entre l’èpiderme et les cellules collenchymateuses des portions de tige lélérement bombées (convexes) et concaves de TVu 946 et IT82D-716. TVu 946 avait une tige de diamètre inférieur à celui de la tige dTT82D-716. La partie située entre les tissus de l’épicarpe et du mésocarpe des gousses de TVu 946 et IT82D-716, âgées de 7 jours, n’a pas laissé paraître de différence significative entre les deux variétés. Une certaine similarité dans l’arrangement des cellules et des tissus ainsi que l’absence de tissus de renfort dans la paroi des gousses seraient la principale cause de leur vulnérabilité aux dégâts des larves.
L’anatomie de la tige est considérée comme un facteur important pour la résistance de la tige à M. testulalis; toutefois, il semblerait que cela ne s’applique pas à la résistance des gousses.
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Oghiakhe, S., Jackai, L.E.N. & Makanjuola, W.A. Anatomical Parameters of Cowpea, Vigna Unguiculata (L.) Walp. Stem And Pod Wall Resistance To The Legume Pod Borer Maruca Testulalis Geyer (Lepidoptera: Pyralidae). Int J Trop Insect Sci 12, 171–176 (1991). https://doi.org/10.1017/S1742758400020658
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DOI: https://doi.org/10.1017/S1742758400020658