Simple density estimation using presence–absence sampling for the cotton aphid Aphis gossypii (Glover) on strawberry plants

Abstract

To examine simple density monitoring, the mean number of Aphis gossypii (Glover) on strawberry plants was estimated from the proportion of leaflets parasitized by A. gossypii. The relationship between the mean number of aphids and the sample variance of aphids fits Taylor’s power law better than Iwao’s m^*–m regression. The relationship between the proportion of parasitized leaflets and the mean number of aphids on leaflets at various census dates fits the Kono–Sugino equation. The mean number of aphids was estimated using the proportion of parasitized leaflets. To estimate populations with a fixed level of precision, the smallest sampling size was obtained from Kuno’s equation. For this estimation 168 strawberry leaflets were examined. The mean density of A. gossypii was estimated from the proportion of parasitized leaflets between 10% and 90%, with a fixed level of precision.