Resistência de genótipos de meloeiro à mosca-minadora, Liriomyza sativae Blanchard (Diptera: Agromyzidae)

Abstract

The leafhopper (Liriomyza sativae) today is considered one of the main plagues of melon in Brazil, which has been stimulating the abusive use of insecticides to overcome the problems caused by the pest. In this sense, the use of resistant cultivars is a promising alternative. Thus, the present study aimed to evaluate the resistance of melon genotypes in relation to the fruit fly. For that, 21 genotypes of melon were evaluated, from the Genetic Improvement Program of Meloeiro of Embrapa, and the commercial hybrid "Goldex" testifies. The non-preference for oviposition and feeding were evaluated in tests with and without a choice; The effect of genotype antibiosis through larval and pupal viability; As well as the number of trichomes and volatile compounds present in the leaves. For evaluation, the following genotypes AC 35, AC 43, 341, 343, 333 and the Goldex hybrid were selected for the morphological characterization of leaves (adaxial and abaxial) and release of volatile compounds. Quantification of trichomes was carried out in Scanning Electron Microscope (SEM), where the number of trichomes was quantified and correlated with oviposition and plague feeding. The volatile analyzes in the melon leaves were carried out using the solid phase microextraction technique coupled to gas chromatography with mass spectrometry (SPME-GC-MS). As for the non-preference for oviposition (number of oviposition punctures) and feeding (number of feeding punctures), there was no difference between the genotypes and the Goldex control, in a test with a chance of choice. However, in the confinement test, genotypes 343 and AC 43 were the least oviposited by L. sativae, with mean values of 0.9 and 1.3 respectively; While genotype 343 was the least preferred for feeding, with 0.7 feeding punches / 4cm in diameter. As for larval and pupal viability, nine genotypes were more promising: 339, 346, 343, 341, 334, 331, 333, 313 and 330, and a possible antibiosis effect was found in these treatments. In relation to the density of trichomes, there was no difference between the treatments and no correlation was found between the density (adaxial and abaxial) and the number of oviposition and feeding punctures. For the volatile analysis of the leaves, a total of ten volatile compounds distributed among the treatments were obtained. From this study it is suggested to have antibiosis resistance in the nine genotypes mentioned above and the presence of some degree of antixenosis in genotypes 343 and AC43, but the trichomes and volatile compounds identified in the melon genotypes do not present any action Antioxenotic for oviposition and feeding of L. sativae.