Bemisia argentifolii (Homoptera : Aleyrodidae) colonization on upland cottons and relationships to leaf morphology and leaf age

We compared Bemisia argentifolii Bellows & Perring colonization on Stonevil le (ST) 474 and Deltapine (DPL) 5415 cottons, Gossypium hirsutum L., in the field. We also examined leaf trichome density, leaf age, and leaf morpholo gical characteristics as possible factors influencing cultivar host selecti on. The increased numbers of all B. argentifolii life stages on ST 474 in t he field appeared to be related to the higher trichome density on abaxial l eaf surfaces compared with DPL 5415. In both cultivars,leaves from node num ber 1 below the terminals were smaller and had higher vascular bundle densi ties and numbers of lysigenous glands than older, larger leaves. Younger le aves also had smaller leaf areole areas, more terminal vein endings per uni t leaf area, and shorter distances from abaxial leaf surfaces to minor vein phloem tissues compared with older leaves. These younger leaf morphologica l characteristics may contribute to the higher B, argentifolii densities on younger leaves. In the laboratory, electronically monitored adult females and visually monitored settled first and fourth instars preferred. to probe into secondary and tertiary leaf veins as compared with main and primary l eaf veins.