Development and Reproduction of the Burdock-infesting Aphid, <i>Uroleucon gobonis</i>（Matsumura）, and the Effects of Insecticide Application on Aphid Densities

Abstract

The developmental times and reproduction of the burdock-infesting aphid, Uroleucon gobonis (Matsumura ) , were determined at different temperatures. The developmental zero, effective cumulative temperature, and intrinsic optimum temperature for the development of this aphid were estimated to be 5.27 C, 141.71 degree-days, and 19.22 C, respectively. This species had growth retardation at 27 C, and no nymphs reached the adult stage at 32 C. Like other aphids, it was found to be strong against low temperatures and weak against high temperatures. The intrinsic rate of natural increase of U. gobonis was 0.26 at 12 C, followed by 0.29 at 17 C, and 0.51 at 22 C suggesting that U. gobonis has a higher reproductive ability at low temperatures than other reported aphid species. Assessment of insecticide susceptibility using the leaf and body dipping methods showed that U. gobonis was highly susceptible to the recommended field rates of the 10 insecticides tested. Clothianidin granules(6 kg/10 a )applied to depths of 2 or 5 cm in the soil significantly suppressed aphid densities compared to surface treatment and the nontreated control. Acetamiprid granules(6 kg/10 a )also showed the same effect as clothianidin granules(6 kg/10 a )on the aphid density, and halving the dose showed no reduction in effectiveness.