Resistance of Lycopersicon species to Bemisia tabaci, a tomato leaf curl virus vector

Abstract

More than 1200 cultivars, breeding lines, and wild species of Lycopersicon were screened for resistance to the tomato leaf curl virus under field conditions. All accessions of Lycopersicon esculentum were found susceptible to tomato leaf curl virus. Three lines of Lycopersicon hirsutum and one of Lycopersicon peruvianum accessions showed apparent resistance to the tomato leaf curl virus owing to the failure of virus transmission by whiteflies. Morphological analysis by light and scanning electron microscopy revealed distributions of different types of trichomes on leaf surfaces. Lycopersicon hirsutum proved to be the least affected by the leaf curl virus because it did not support whitefly infestation to any extent. Lycopersicon hirsutum differed from other species by the presence of glandular trichomes designated type VIc. Whiteflies became entrapped in the exudate of type VIc trichome glands before they could transmit the virus. Thus, it may be possible to control tomato leaf curl virus transmission by breeding plants with certain types of trichomes, especially trichome type VIc. Key words: leaf curl virus, nonpreference, physical resistance, glandular exudate, trichomes, whitefly.

Biological aspects of the beetle Delphastus davidsoni fed with whitefly eggs laid on tomato genotypes

“…In our study, type V trichomes were not subdivided into Va and Vb, and no type VIII trichome, as defined by Channarayappa et al (1992), was identified. The counting of these trichomes may have been hampered by the technique used; it is possible that these trichomes were broken during glass slide preparation.…”

“…Nonglandular trichomes (II, III and V) are highly similar to each other, differing only in length; out of these, type V is the shortest nonglandular trichome and the most commonly found on tomato leaves. Glandular trichomes (I, IV, VI and VII) have 'heads' that release allelochemicals; of these, only type VI and type VII have multicellular tips (Snyder and Carter, 1985;Channarayappa et al, 1992;Simmons and Gurr, 2005). Because of the great diversity of trichomes found on the leaf surface, some trichomes were subdivided -type V (Va, Vb and Vc) and type VI (VIa, VIb and VIc) -and a new type (VIII) was characterized (Channarayappa et al, 1992).…”

“…Glandular trichomes (I, IV, VI and VII) have 'heads' that release allelochemicals; of these, only type VI and type VII have multicellular tips (Snyder and Carter, 1985;Channarayappa et al, 1992;Simmons and Gurr, 2005). Because of the great diversity of trichomes found on the leaf surface, some trichomes were subdivided -type V (Va, Vb and Vc) and type VI (VIa, VIb and VIc) -and a new type (VIII) was characterized (Channarayappa et al, 1992). The PI134418 genotype presented the greatest number of glandular trichomes (13.7 trichomes mm −2 ), followed by IAC294 (4.2 trichomes mm −2 ).…”

“…This compound causes increases in larval and pupal mortality rates and larval and pupal developmental time, in addition to pupal deformation (Leite, 2004). 2-TD also induces feeding non-preference in adult and young insects and causes oviposition non-preference (antixenosis) in other pests, including B. tabaci (Channarayappa et al, 1992), Myzus persicae (Sulzer) (Hemiptera, Aphididae) (Leite et al, 1999), Frankliniella occidentalis (Pergande) (Thysanoptera, Thripidae) (Kumar et al, 1995). Yet, the relatively small size of the first larval instars of D. davidsoni may have led to a greater concentration of 2-TD in their bodies, as suggested by Leite (2004), causing high larval mortality rates on PI134418 and IAC294.…”

Comportamento de oviposição da mosca-branca Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) biótipo B em tomateiro

“…Os tricomas podem interferir mecanicamente na oviposição, na fi xação e na alimentação de insetos em razão de quatro principais características: densidade, ângulo de inserção, comprimento e tipo (Channarayappa et al 1992).…”