Control of ground beetles (Col., Carabidae) attacking strawberry fruits

Experiments in south-east England are described in which insecticides were tested against the Carabid beetles Harpahis rufipcs (Deg.) and Feronia melanaria(111.), which cause damage to strawberry fruits.In preliminary screening tests, the mortality of H. rufipex was low when adults were caged with fruits or straw treated with rotenone at 0·004 per cent, or with carbaryl, DDT, dimethoate, malathion, mevinphos, nicotine, TEPP, toxaphene and trichlorphon at one or more concentrations in the range 0–06–0–2 per cent. In small-scale field trials, γ BHC at 0·026 per cent, gave poor results but chlordane and dieldrin exhibited persistent toxicity.In further tests with fruits, field-weathered deposits from sprays containing 0·1 or 0·2 per cent, dieldrin caused over 90 per cent, mortality for 7 and 21 days, respectively, but left residues at harvest of 0·5 p.p.m., which were considered too high for consumer safety.Dieldrin applied to soil at 5 lb. per acre resulted in 100 per cent, mortality for 28 days in 1957, but gave very variable results in 1958. Conversely, aldrin at 5 lb. gave effective mortality for only 14 days in 1957 but for the maximum test period of 89 days in 1958; no satisfactory explanation was found for the seasonal differences. Aldrin at 10 lb. per acre gave 100 per cent, mortality for 77 and 89 days, respectively, in the two years. Tests of soils into which measured quantities of insecticide had been incorporated, resulted in 100 per cent, mortality, after 4 days' exposure, with aldrin and dieldrin at levels of 2–4 and 16–32 p.p.m., respectively; endrin at 64 p.p.m. was only slightly toxic.In field trials in 1959–60, application of aldrin at 10 lb. per acre to the surface of the soil around the plants in sprays in late April immediately before flowering, or at 5 lb. per acre in late May before laying straw below the fruit, reduced fruit damage due to H. rufipes or F. melanaria by 66–94 per cent. Residues at harvest were of the order of 0·03 p.p.m., and no effect on flavour was detected in processed fruit from plots treated at either time of application.