Distribution of Aphids in Spring Cereals

Publisher Website
Google Scholar
Abstract
Aphids, mainly Metopolophium dirhodum with fewer Sitobion avenae, invading cereals in May were scarce until after mid-June, most in mid-July, and gone after early August. Aphid densities were larger in 1970 than in 1971, but they probably affected grain yield for only about a week in July 1970. In June, S. avenae occurred mainly around the crop edge, while Metopolophium dirhodum was widespread. In July, Sitobion avenae infested the whole crop, with most in sheltered areas, whereas Metopolophium dirhodum was common everywhere. Both species occupied the leaves until after heading, when most Sitobion avenae invaded the ears and most Metopolophium dirhodum remained on the leaves. In 1970, M. dirhodum `groups' were larger (max. 79) than Sitobion avenae `groups' (max. 42) but in 1971, they were similar and smaller (max. 38 S. avenae). S. avenae occurred singly more often than Metopolophium dirhodum. In 1970, the largest `groups' of M. dirhodum appeared a week before, and of Sitobion avenae up to 5 weeks before, the maximum numbers of `groups'/0.3 m, whereas they coincided in 1971. Mean numbers of `groups' and aphids/0.3 m were related, but `group' size was independent of population size. Statistical differences between the indices of aggregation (b) for three aphid species could not be demonstrated.

This publication has 0 references indexed in Scilit: