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A SAMPLING SYSTEM FOR ESTIMATING EGG AND LARVAL POPULATIONS OF AGROMYZA FRONTELLA (DIPTERA: AGROMYZIDAE) IN ALFALFA12

Published online by Cambridge University Press:  31 May 2012

D. G. Harcourt  and
M. R. Binns
D. G. Harcourt
Affiliation:
Ottawa Research Station, Agriculture Canada, Ottawa K1A 0C6
M. R. Binns
Affiliation:
Engineering and Statistical Research Institute, Agriculture Canada, Ottawa K1A 0C6
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Abstract

During 1977, a detailed study was undertaken to develop efficient sampling procedures for estimating egg and larval populations of the alfalfa blotch leafminer, Agromyza frontella (Rond.), in Vernal alfalfa. Distributions of the stages within and between stems were contagious and stem totals tended to follow negative binomial distributions. Within stems, the density of eggs and larval mines increased exponentially from base to tip. Taking these patterns and the costs of sampling into account, and using the relevant components of variance, four leaves taken systematically from a single stem is proposed as the appropriate sample unit for both eggs and mines. On this basis, 200 stems per field will give adequate precision (less than 10% of the mean with confidence probability 90%) for population estimates. However, the propensity of the leafminer to prefer the middle leaflet to the basal leaflets in the approximate ratio 3:4:3 suggests that sampling costs may be further reduced by restricting counts to the middle leaflet and raising them by a factor of 2.5.

Type
Articles
Information
The Canadian Entomologist , Volume 112 , Issue 4 , 01 April 1980 , pp. 375 - 385
Copyright
Copyright © Entomological Society of Canada 1980

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