Cassava Varieties Trichome Density Influence the Infestation of Vatiga illudens (Hemiptera: Tingidae)

Abstract

The objective of this study was to evaluate the infestation of Vatiga illudens in cassava varieties and to correlate its infestation with the physical and morphological parameters of resistance. The experiments were conducted in the 2014/2015 and 2016/2017 seasons, out in a randomized complete block design with nine treatments and five replicates. Nymphs and adults of V. illudens were evaluated on the abaxial surface of 16 leaves of the middle third of the plant. The density of trichomes was quantified with the use of electron micrographs, and the roughness of the epicuticular wax was assigned to the leaves of the shoot and the apical third. The color components L*, a*, b*, were measured with a portable digital colorimeter. The cultivars IAC 90 and Santa Helena demonstrated the smallest infestations in the 2014/2015 season and maintained low infestation in the 2016/2017 season. The varieties Baianinha, IAC 576-70 and Catarina-Branca, maintained high infestations in the both seasons. The density of trichomes of the middle third of the plants correlated negatively to the V. illudens infestation for the two seasons. The higher density on trichomes, negatively affects the infestation of V. illudens in cassava varieties, characterizing as a specific resistance factor to this species.

Are epicuticular waxes a surface defense comparable to trichomes? A test using two Solanum species and a specialist herbivore

“…macrocarpon, creating a comparatively stronger physical barrier against stresses. Higher trichome density is usually associated with decreased herbivory (Fordyce and Agrawal, 2002;Eaton and Karba, 2014;Pastório et al, 2019;Watts and Kariyat, 2021b) and increased abiotic stress tolerance (Liakoura et al, 1997;Li et al, 2018). Thus, we expected S. macrocarpon to be more resistant to herbivore feeding than S. glaucescens, but this was not the case.…”

Decoding Antixenotic Mechanism of Resistance in Cassava Genotypes against Whitefly, <i>Bemisia tabaci</i> (Gennadius)

“…For scanning electron microscope (SEM) analysis 1 mm 2 area from the central leaf lobe's median section of each cassava cultivar was carefully excised using a scalpel. Before SEM imaging these samples were processed according to Pastório et al (2019).…”

Resistance of Common Bean Genotypes to Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae)

“…The leave's adaxial central portion in the plant's upper third region was used. A black background was used behind the leaf to avoid reflected sunlight influence [33].…”