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Insecticide granule distribution and the control of Lycoriella auripila (Diptera: Lycoriidae) in mushroom casing material
Author(s) -
BINNS E. S.
Publication year - 1974
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.1744-7348.1974.tb01493.x
Subject(s) - casing , biology , mushroom , toxicology , granule (geology) , diazinon , zoology , botany , agronomy , pesticide , paleontology , petroleum engineering , engineering
SUMMARY In laboratory tests the distribution of insecticide in peat–chalk mushroom casing greatly affected the number of adult sciarids which emerged from larvae placed in 50 g samples. Only thionazin markedly reduced emergences when granules were clumped in the centre of the sample of casing. The slope of dosage mortality data for clumped granule treatments was less steep than for mixtures and gave estimated LD 95 values of 16300 and 26.8 ppm respectively. Thus, the number of adults which emerged when granules amounting to 6.4 mg of chlorfenvinphos were clumped was 65% of those emerging when only 0.4 mg a.i. was mixed into 50 g casing. However, adults did not emerge when 3.2 mg of the same insecticide was mixed throughout the sample. Increased doses did not, therefore, compensate for inadequate mixing. With 0.2–0.4 mg a.i. chlorfenvinphos mixed through the casing, about three times as many sciarids emerged with the intact granules than when pulverized granules were used. This showed the lack of mobility of this chemical in peat‐chalk mixtures and the need for it to be homogeneously incorporated in commercial casing. Pirimiphos‐ethyl, diazinon and thionazin also gave improved kills when mixed into the casing rather than clumped. A χ 2 test of the mortality data suggested a non‐linear dosage‐mortality relationship for treatments amounting to half the dish. However, LD 95 estimates of 37.5 and 62.2 ppm were obtained for mixed and quadrant treatments. Thus, when 3.2 mg chlorfenvinphos was mixed into only half of the volume of casing, the number of adults emerging was only 6% of that from untreated casing. However, larval movement was negligible in untreated casing and this appeared to limit the effectiveness of chlorfenvinphos and pirimiphos‐ethyl when they were not evenly distributed throughout the casing. With thionazin and diazinon, mobility of the insecticide appeared to compensate for uneven distribution.