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The distribution and analysis of cabbage root fly egg populations
Author(s) -
FINCH S.,
SKINNER G.,
FREEMAN G. H.
Publication year - 1975
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1975.tb01516.x
Subject(s) - biology , aestivation , first generation , range (aeronautics) , brassica , botany , sampling (signal processing) , negative binomial distribution , horticulture , third generation , pest analysis , statistics , agronomy , ecology , mathematics , population , demography , telecommunications , materials science , poisson distribution , filter (signal processing) , sociology , computer science , composite material , computer vision
SUMMARY The distribution of the egg stage of the cabbage root fly around brassica plants was studied at Wellesbourne on 0.05–0.4 ha plots during 1970 and 1971. The three generations of flies occurred at similar times in both years and the numbers of eggs collected generally decreased from the first to the third generation. Differences between generations demonstrated that each generation should be treated separately. The number of plant samples required for a given level of precision increased from the first to the third generation, indicating that experiments relying on egg counts should be planned to coincide with the first generation whenever possible. A sampling plan for the range of oviposition normally encountered during the three generations is illustrated for both one‐ and five‐plant samples. For the same level of precision, estimates of the populations from five‐plant samples required only 50% to 80% of the time of those from one‐plant samples. When aestivation occurs the peak of oviposition in the second generation is difficult to determine, and designed experiments should not be undertaken. The negative binomial distribution failed to describe the clumping of the eggs for a complete generation, since a common k could not be fitted to the data. The distribution of the eggs was best described by Taylor's power law which showed that although sampling factors changed with generation, the value of the power did not. A value of 1.4 appears to be the index of aggregation characteristic of the egg stage of this species.