Evaluations of PH 60-40,an insect growth regulator, for control of the stable fly Stomoxys calcitrans (L.) : (Diptera, Muscidae)

' A new insect growth regulator, PH 60--40 (N-(4-chlorophenyl)-N'-(2,6difluorobenzoyl) urea] was tested on the mature larvae of the stable fly, Stomoays calcit'rans (L,), by a fly medium method and by hens as a feed additive. One ppm of PH 60-46 in the fly breeding medium gave almost complete inhibition of the cuticle formation of the flies during pupal metamorphosis. PH 60-40 also satisfactorily suppressed adult emergence from chicken manure at the same concentrations. Thus, PH 60-40 seems to be ethcient for control of the stable fly. INTRODUCTION Outbreaks of the stable fly occurs frequently at big poultry farms and become a serious nuisance to humans and livestocks in the vicinity (Mizusawa Animal Hygiene Station, 1971). Although conventional insecticides such as organophosphorous and carbamate compounds are used effectively as larvicides, the development of resistance to them has been attracting much attention. As a replacement, a new group of insecticidal cornpounds which interfere with cuticle deposition of insects by ingestion were reported by Mulder and Gijswift (1973) and Wellinga et al. (1973). One of those compound, TH 6040 (same to PH 60-40 tested in the present paper) was demonstrated to be very promising for control of dipterous larvae by Miller (1974} and Wright (1974). In the present paper, the insecticidal activity of PH 60-40 was evaluated against the mature larvae of the stable fly by applying to the fly breeding medium and by oral administration to laying hens. " * 4Jilgx': stSicacinat'zakptvabi (+ o2o-ol i'\.EptmadiTMJ11*ilZ4) 261 METHODS AND MATERIALS The compound used in the present tests was provided by Philips-Duphar B, V, as a 25 96 water dispersible powder of PH 60-40. The stable fly was a native strain which had been reared at Tohoku National Agricultural Experiment Station, Morioka. iFlly 7nediu7n tests. The fly breeding medium for 100 larvae was consisted of 12g of powdered rat food, 6g of saw dust and 32 ml of distilled water. The mature Iarvae were placed on the test fly medium containing PH 60-40 at the desired concentration which ranged from O,lppm to 100ppm. The treated larvae were held in an incubator at 250C and 70 ?!o RH, with 12 hrs fluorescent illumination periods a day. The number of pupation and adult emergence of the treated larvae were recorded. The pupae from which adults did not appear until 14 days after pupation were dissected and examined microscopically to determine the developmental stage of the fiy. The test was repeated twice. Fleeding triats. Five greups of 3 mature laying hens, White Leghorn$, were fed for 17 days on diets with O, 1, 5, 12.5 or 25 ppm of PH 60-40. Manures were collected for