CGA‐72662—A new sheep blowfly insecticide

Abstract

The efficiency of 2-cyclopropylamino-4, 6-diamino-s-triazine CGA-72662 (proposed common name: cyromazine) for the control of blowfly strike was tested in fly cage and field trials on sheep. The safety to sheep and physico-chemical properties of the compound as they relate to blowfly control were also assessed. When the sheep were thoroughly jetted with a solution of CGA-72662 containing 1g of active ingredient per litre, the mean incidence of fly strike in 7 field trials was reduced from 16.5% to 1.5% over a period of 9 weeks. The incidence of strike in the treated sheep in 2 insectary tests, which imposed levels of fly activity far in excess of that usually encountered in the field, was reduced from 93% and 73% in untreated sheep to 2% and nil respectively over a period of 8 weeks. Jetting with CGA-72662 solutions 100 times greater than the recommended concentration did not produce any side effects in sheep. Three treatments at twice the recommended concentration during the first trimester did not affect pregnant ewes nor their progeny. The compound was safe to use in combination with common anthelmintics and with sheep dips used for control of lice. CGA-72662 was stable in solution. No stripping occurred in dips and it persisted on wool for a considerable period. A satisfactory alternative to the organophosphorus insecticides has been found in CGA-72662, since it provided a substantial increase in residual protection against blowfly strike with a high degree of safety.

Prevention of blowfly strike on coarse and fine woolled sheep with the insect growth regulator dicyclanil

“…The incidence of flystrike in field trials at different sites may vary considerably. 2,3,4,15 This variation has been shown to be related to both the abundance of blowflies and to a range of climatic and other environmental factors affecting susceptibility of sheep to flystrike. 16,17,18 For the dicyclanil treated sheep in trial 1 (coarse woolled sheep) the 2% limit was reached at week 11 after treatment in site 5, at week 12 at sites 3 and 4, and was not reached at the remaining sites.…”

“…C yromazine, a triazine derivative with Insect Growth Regulator (IGR) activity was introduced for flystrike prevention in New Zealand and Australia in the early 1980s 1,2 and later on in Europe. 3,4 Since then other IGR chemicals, especially the benzoyl-ureas diflubenzuron 5,6,7 and triflumuron, 8 have been investigated and some of them are now available for blowfly prevention by farmers in Australia and New Zealand.…”

Long‐lasting prevention against blowfly strike using the insect growth regulator dicyclanil

“…These studies were set up to assess the duration of protection p rovided by each application method at different dose rates under controlled conditions. In vivo artificial infestations have also been used by other investigators 14,15 to assess the efficacy of other compounds to prevent blowfly strike. The artificial conditions during both trials we re attractive enough to encourage L c u p r i n a to oviposit fre q u e n t l y.…”

Predicting insecticide resistance: mutagenesis, selection and response

“…Cyromazine acts as an insect growth regulator (Binnington 1985) and was introduced during the late 1970s to control a number of pests (Hart et al 1982;Iseki & Georghiou 1986;Hughes et al 1989;Sirota & Gra¢us 1994). Moderate levels of resistance have been observed in natural populations of Musca domestica (Bloomcamp et al 1987;Shen & Plapp 1990;Keiding et al 1992), but resistance is yet to evolve in the ¢eld in L. cuprina (Levot 1993;Yen et al 1996).…”