ABSTRACT

The effect of nonviruliferous wheat curl mites (Aceria tosichella Keifer) on yield of the hard red winter wheat cultivar `Ike' was evaluated in field plots. Plots artificially infested with wheat curl mites reared in the greenhouse averaged 8,821 ± 3,814 mites per spike compared with l,166 644 per spike in the naturally infested controls. The yield of the infested plots (3,707 ± 401 kg/ha) was significantly less (17%) than the naturally infested control plots (4,481 ± 349 kg/ha). Assuming a linear effect, which may or may not be valid, it is estimated that a 1% loss in grain yield may result from 450 wheat curl mites per spike. Test weights and 1,000 kernel weights were also significantly lower for the infested plots than for the naturally infested controls. There were no significant differences among treatments for numbers of kernels per spike or for any other variables associated with the May 1, 8, and 15 dates of infestation. These results indicate that wheat curl mites cause yield losses to wheat aside from that caused by the viruses they vector. The limited information available on natural infestations of wheat spikes indicates that yield losses due to wheat curl mites may range from less than 1% to 15%.

wheat yield, wheat curl mite, Acari, Eriophyidae, Aceria tosichella Keifer, vector, nonviruliferous

¹Accepted for publication 26 October1999.