Evaluation of a choice-test method to assess resistance of melon to Aphis gossypii Glover (Homoptera: Aphididae) by comparison with conventional antibiosis and antixenosis trials

The Vat gene of melon confers resistance to Aphis gossypii through both antixenotic and antibiotic mechanisms.This article reports several experiments carried out to detect this gene in melon lines from a melon breeding program.These included antixenosis, antibiosis and virus transmission trials.Results showed that, for Vat detection, antibiosis trials were not as discriminating as antixenosis trials.The antixenosis trials discriminated more clearly between resistant and susceptible lines after 72 h than after 24 h.We additionally developed a rapid and simple choice-test method to assess antixenotic effect.This test discriminated rapidly and effectively between resistant and susceptible lines.The aphids showed significant rejection of resistant lines after only 1.5 h of exposure.Thus compared to the conventional antixenosis trials this test has several advantages, including rapidity, ease of use, and non-destructiveness (allowing replicate testing of a single plant, or subsequent obtention of seed).