The whitefly Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) in processing tomato crop – attack differences among four cultivars

Mestrado em Engenharia Agronómica / Instituto Superior de Agronomia. Universidade de Lisboa

The Portuguese 2017 processing tomato season was one of the worst regarding the color parameter. The tomato coming from Ribatejo region fields was showing symptoms of irregular ripening disorder (IRR), probably caused by the large population of Bemisia tabaci present. This pest, favoured by global warming, by its versatility and resilience, has the potential to become a major pest, hence relevant to analyse different management alternatives in the processing tomato crops, such as the development of lesser susceptible or attractive cultivars (cvs). Several studies carried out on wild Solanum spp. species revealed the existence of resistance to B. tabaci through its trichomes. However, as far as we know, there are no studies conducted on cvs commonly used by farmers, either on susceptibility to this pest or on the type and distribution of its trichomes, which may influence it. This study aimed to verify and compare abundance and type of trichomes, glandular and nonglandular, in four commercial processing tomato cultivars (CXD277, H1015, H3402 and KG273) and evaluate its influence on B. tabaci attractiveness. To achieve that, two free choice trials were performed in Kagome’s greenhouse at Águas de Moura. The greenhouse was uniformly infested with B. tabaci specimens. The trichomes count was done using a stereoscopic microscope and the type recognition by scanning electronic microscopy. The analysis of variance did not reveal significant differences in the number of either nonglandular, glandular trichomes or both combined. The analysis of the number of nymphs on the leaves, excluding H3402, revealed a significant lower number of nymphs on KG273, but only in the 1st trial. There were no correlations between nymphs and trichomes counts. So, this factor was considered not determinant for a different infestation and, probably, does not play a role on different attractiveness of B. tabaci on commercial cvs. Other factors that can affect attractiveness are discussed

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