Insecticidal effect of deltamethrin, dinotefuran and spiromesifen against the sugarcane whitefly Neomaskellia andropogonis on CP69-1062 sugarcane cultivar

SummaryThe sugarcane whitefly, Neomaskellia andropogonis Corbett (Homoptera: Aleyrodidae), is one of the important pests of sugarcane in Iran. The use of selective chemical insecticides helps to suppress whitefly infestations. Although several insecticides from various groups have been registered to control whiteflies, this is the first study to test the efficacy of deltamethrin, dinotefuran and spiromesifen insecticides against eggs, second instar nymphs and pupae of the sugarcane whitefly on CP69-1062 sugarcane cultivar. Five concentrations of the tested insecticides were applied in a leaf dipping bioassay under laboratory conditions. Probit analysis indicated that deltamethrin and dinotefuran with LC50 values of 50.1 and 49.5 ppm were the most toxic insecticides against eggs of N. andropogonis. Deltamethrin controlled nymphal and pupal stages more effective than the other two tested insecticides and the LC50 values were 49.7 and 5.44 ppm on nymphs and pupae, respectively. The LC50 values of dinotefuran on second instar nymphs and pupae were 564.7 and 78.7 ppm and the values were 270.9 and 18.3 ppm for spiromesifen, respectively. The results support the use of the insecticides in rotation according to their different mode of action in integrated pest management programs of the sugarcane whitefly N. andropogonis.

Biology, natural enemies and damage of the sugarcane whitefly (Neomaskellia andropogonis) (Homoptera: Aleyrodidae) in Iran

An outbreak of the sugarcane whitefly (Neomaskellia andropogonis Corbett) recently occurred in sugarcane fields in Khuzestan Province of Iran. This pest sucks plant sap producing large amounts of honeydew. In Khuzestan Province, populations of all developmental stages increase from early August until late November. At this time, when sugarcane is at the ripening stage, nymphs suck the sap, and in cases of severe infestation, retard the growth of sugarcane plants. In this study, we investigated the biology of the pest on different cultivars of sugarcane and under different temperatures. Also, we conducted experiments to determine the damage caused by the pest in the field. Mean pre-adult developmental times were 24.09, 28.06, 27.27 and 26.64 days on CP69-1062, CP57-1062, CP48-103 and NCO-310 cultivars, respectively, and only female progeny were produced. Mean longevity of females on the four cultivars was 6, 8.49, 4.15 and 4.60 days, respectively. Adult females laid an average of 61.80, 58.80, 41.10 and 39.38 eggs on the four cultivars, respectively. Results show that the optimum temperature for development of different stages of N. andropogonis is 30±1°C during the day and 25±1°C at night, and at this temperature, egg and nymphal duration (including first, second, third instars and pupae) and adult longevity were 6.2, 17.0 and 7.6 days, respectively. Females of cultivar CP69-1062 laid an average of 50.09 eggs. Analysis of data on the quality of damage (including Brix, pol and refined sugar factors) shows that damage was inversely and significantly correlated with the number of infested leaves. Whitefly damage differed among cultivars; and, based on the quality of damage, early maturing cultivars were more susceptible to whitefly damage. We collected two parasitoid wasps from nymphs—Encarsia inaron (Walker) (Hym.: Aphelinidae) and Eretmocerus delhiensis Mani (Hym.: Aphelinidae). To the best of our knowledge, this is the first study to assess the biology, damage and natural enemies of N. andropogonis on sugarcane in Iran.