In laboratory experiments, all stages of the Egyptian cotton-leaf worm (Spodoptera littoralis (Boisd.)) were killed by exposure at 1–2%C for ten days, but the peach-potato aphid (Myzus persicae (Sulz.)) and the red spider mite (Tetranychus urticae (Koch)) were not controlled by this treatment. When exposed to methyl bromide, all the S. littoralis eggs tested were killed by a concentration × time product (CTP) of 44 mg h/litre at 18%C, but control of all stages of M. persicae and T. urticae required a CTP of at least 88 mg h/litre.
SUMMARYThe relationships between increased oxygen uptake and locomotor ataxy or death induced by LD50's of n‐valone (2‐n‐valeryl‐1,3‐indandione), γ‐BHC, p,p'‐DDT, dieldrin, DNBP (2,4‐dinitro‐6‐sec.‐butylphenol), malathion and allethrin, in individual lesser mealworm beetles (Alphitobius laevigatus F.) have been investigated. n‐Valone did not increase the rate of oxygen uptake of treated beetles. After dosage with DDT or malathion, increased oxygen uptake occurred only in beetles which were knocked down and beetles knocked down always died. After dieldrin treatment, increased oxygen uptake was always associated with knock‐down, but a few knockeddown beetles recovered. γ‐BHC, allethrin or DNBP caused knock‐down or serious locomotor ataxy and increased oxygen uptake in all the treated beetles, but those which eventually died reached higher peaks in rate of oxygen uptake. The similarities and differences between the effects of the various insecticides are discussed together with some aspects of their possible mode of action.
SUMMARY
The damage caused to unrooted chrysanthemum cuttings by methyl bromide fumigation was lessened by storing the cuttings for one day at 4°C before fumigation at 18°C. After such storage, the addition of 10 per cent carbon dioxide to the fumigation atmosphere did not affect the damage caused. There was significant variation in the damage suffered by different cultivars when unrooted cuttings were fumigated at 4 and 18°C and rooted cuttings at 18°C.
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