Leaf morphology of melon mediates feeding and oviposition preference, and immature survival of Liriomyza sativae (Blanchard) (Diptera: Agromyzidae)

To assess the influence of melon genotypes on the feeding and oviposition preferences and survival of L. sativae immatures, a study was carried out by offering 21 melon genotypes (no-choice tests). Among the genotypes, 18 were the least preferred by L. sativae for oviposition, as demonstrated by the reduced numbers of eggs laid on the leaves, while 7 were least preferred for feeding, as demonstrated by the reduced feeding punctures inflicted on the leaves. Genotypes CNPH 06–1047-333 and CNPH 06–1047-341 exhibited strong antibiosis resistance, as confirmed by the occurrence of 100% larval mortality. Scanning electron microscopy revealed that for both abaxial and adaxial surfaces of the leaves, the genotypes CNPH 06–1047-343, CNPH 06–1047-341 and CNPH 11–1071-43 had a lower density of trichomes and higher thickness of leaf epidermis when compared to the susceptible genotype. We also found a positive and significant correlation between the number of trichomes and the number of eggs of L. sativae on the abaxial and adaxial surfaces and with the feeding punctures on the adaxial surface of the melon leaves. On the other hand, the thickness of the leaf epidermis was negatively correlated with the number of insect eggs on the abaxial and adaxial surfaces and with the feeding punctures on the adaxial surface of the leaves. Antixenosis (feeding and oviposition preferences) on melon plants towards L. sativae is associated with a lower number of trichomes and to a higher thickness of the epidermis of leaves. Causes implicated to antibiosis should be further investigated.