Response of Several Pest Species to Cucumis melo L. Lines Resistant to Aphis gossypii Glover1

Abstract

Populations of Aphis gossypii Glover and its natural enemies, and of Liriomyza sativa Blanchard and Empoasca abrupta DeLong were determined on 3 sib progenies in the F4B6 generation from crosses of the aphid-resistant Cucumis melo L. line LJ90234 to each of 4 recurrent parents: ‘Top Mark,’ ‘PMR 45,’ ‘Perlita’ and ‘Gulf Stream.’ E. abrupta was moderately abundant on the 4 recurrent parents and most of the progenies. Only one aphid-resistant progeny, 47946 with Perlita as the recurrent parent, had significantly fewer E. abrupta than certain other lines; it is not known if this was due to genetically based resistance. None of the progenies supported greater populations of E. abrupta than the recurrent parents and none suffered excessive injury from feeding by this insect. No differences were observed in the degree of cotyledon infestation by L. sativa. Recurrent parent Top Mark had statistically fewer mines/leaf than did PMR 45. Certain progenies having Top Mark as their recurrent parent had significantly fewer mines/leaf than PMR 45 and some of its aphid-resistant progenies. Populations of A. gossypii increased rapidly on the recurrent parents following artificial infestation and exceeded 1000/leaf before killing the plants. The rates of increase on all resistant progenies were low and at no time did population means exceed 88/leaf. The plants suffered little injury. No differences were observed in the levels of parasitism of A. gossypii despite the large differences in aphid populations. More aphid predators were observed on aphidsusceptible recurrent parents than on the resistant progeny. Both Frankliniella occidentalis (Pergande) and Tetranychus urticae (Koch) were present in low numbers on all lines, but no significant feeding damage was observed. Results indicate that the breeding strategy followed has eliminated undesirable genes for high susceptibility to E. abrupta which were present in the aphid-resistant parent LJ90234. A muskmelon cultivar resistant to A. gossypii would be expected to have little effect upon the associated complex of arthropods pest species studied herein except through the reduction of A. gossypii populations.