Resistance of cotton genotypes with different leaf colour and trichome density to Bemisia tabaci biotype B

Abstract

The silverleaf whitefly (SLW), Bemisia tabaci biotype B, is considered one of the most serious pests in cotton worldwide. Its control is based on the use of pesticides, which are well‐known for their harmful effects on non‐target organisms and the environment. Here, we examined resistance of several cotton genotypes in terms of antixenosis and antibiosis against SLW. We also investigated the mechanisms of cotton genotypes involved in antixenosis against SLW by correlating with leaf trichome density and leaf colour parameters. In choice tests, we selected resistant cotton genotypes, Gossypium hirsutum palmeri, Aubum 56‐7, G. hirsutum morrilli, Mocó, Nu‐16 (B2 B3 B6)‐ 78/658, Paymaster 53‐816 and ‘IAC 23’, based on SLW oviposition and host preference. No‐choice tests with these genotypes confirmed antixenosis effect on SLW; however, no antibiosis resistance was detected in terms of developmental period and adult emergence rate. We found SLW oviposition preference was positively correlated with trichome density in the abaxial leaf surface, while adult host preference was mostly explained by high levels of green intensity of adaxial surface. Nevertheless, both SLW oviposition and host preference were negatively correlated with the lightness level of adaxial leaf surface. Probably, the underlying mechanism of cotton resistance is based on more than just these two parameters, but our study will contribute to selecting resistant cotton genotypes and helps to understand the mechanisms involved in cotton resistance against SLW. To our best knowledge, this is the first work showing that cotton leaf colour parameters are related to resistance against SLW.