An investigation on the susceptibility of different populations of Melon Aphid, Aphis gossypii G. (Homoptera: Aphididae), to malathion

The melon aphid, Aphis gossypii G., is one of most important pests of agricultural productions. Despitethe problems arising from the use of pesticides, chemical control remains the main method to control of thispest. In current investigation, seven populations of melon aphid (includes: Yazd, Varamin, Mohammadshahr,Esfehan, Pardis Karaj, Hashtgerd and Ramsar) were tested for susceptibility to malathion in laboratoryconditions (temperature: 25±0.2 ºC, Relative Humidity: 60±5%, Photoperiod: 16:8 (L:D)h) after 24 hours.Bioassay experiments on adults were carried out by using leaf dipping method of squash (Cucurbita pepo L.)in different concentrations of malathion. Control treatment was dipped in distilled water. Each test wasreplicated three times and 15 adult female were used for each replication.According to the results, LC50 values of Yazd, Esfehan, Varamin, Hashtgerd, Mohammadshahr, Pardis andRamsar populations were 20.25, 36.32, 38.81, 79.96, 117.94, 159.19 and 162.99 ppm respectively. Resultsshowed that aphids of Yazd and Ramsar populations had the most and the least susceptibility to malathion atthe LC50 values. Ramsar population was 8-fold more tolerant to malathion than Yazd population. Ramsarpopulation than other populations tested were most tolerant to malathion and there is a possibility that melonaphid in this region is tolerant to other organophosphate or carbamate (similar mode of action) pesticides. Soin this area must use pesticide program management to control of melon aphid.

کلیدواژه ها:

Aphis gossypii ، malathion ، susceptibility ، tolerance