The Effect of Sprays on the Fauna of Apple Trees. IV. The Recolonization of Orchard Plots by the Predatory Mirid Blepharidopterus angulatus and Its Effect on Populations of Panonychus ulmi

1 November 1966

journal article
research article
Published by JSTOR in Journal of Applied Ecology

Vol. 3 (2) , 269-+
https://doi.org/10.2307/2401252

Abstract

Following a DDT spray in July 1957 which almost eliminated the predatory Blepharidopterus angulatus from orchard plots of 1/4 acre (1/8 ha), population of Panonychus ulmi increased to a maximum of 100 mites and eggs per leaf in 1958 and then declined to 8 mites and eggs per leaf by 1960, a level which had been maintained on untreated plots throughout the period of the experiment. Adults of B. angulatus invaded the treated plots in Agust 1958; in 1959 the numbers were equal to those on the untreated plots, and by 1960 larval populations of the predator on the ''DDT'' plots exceeded those on the controls. Dispersal of adult B. angulatus from all plots occurred in 1960. B. angulatus decreased leafhopper populations, which were further attacked by a parasite, Aphelopus sp., in 1959.

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