Dr. Murai Éva szerk.: Parasitologia Hungarica 19. (Budapest, 1986)
Parasit, hung. 19. 1986 The effect of cyromazine (IGR) on the third-instar larvae of Musca osiris Wiedemann, 1830 (Diptera: Muscidae) Dr. Róbert FARKAS Department of General Zoology and Parasitology, University of Veterinary Science, Budapest, Hungary "The effect of cyromazine (IGR) on the third-instar larvae of Musca os iris Wiedemann, 1830 (Diptera: Muscidae)" - Farkas, R. - Parasit. hung., 19: 77-80.,1986. ABSTRACT. A trial was carried out to test the efficacy of cyromazine (Neporex**) against third-instar larvae of laboratory strain of Musca osiris Wiedemann, 1830. Its effect was studied at 0.1, 0.5, 1 and 2 ppm concentrations in rearing medium. It can be established that cyromazine is effective against previously not tested M usca osiris. Parallel to a decrease of drug concentration the effect became less pronounced. The larvae were able to develop and to pupate at each concentration but a significant part of the resulting pupae were deformed. Most of them were rod-like, C-shaped, elongated or smaller than the normal ones. At higher concentrations (1 and 2 ppm) the development of adults from pupae was completely prevented. At lower concentrations (0. 5 and 0. 1 ppm) the extent of abnormality varied from no eclosion to complete eclosion. At a level of 0. 5 ppm pupal mortality was 64 per cent. There were two incomplete adult eclosions. At the lowest concentration pupal mortality was 48 per cent. In 16 cases the imagos died at different stages of hatching. R KEYWORDS: cyromazine, Neporex , Musca osiris (Diptera: Muscidae), morphogenetic effect. Cyromazine (N-cyclopropyl- 1, 3, 5 triazine-2, 4, 6-triamine) is one of the hormonally active materials which cause physiological or/and morphological changes during the growth and development of several arthropod species. This new group of the third generation pesticides is called insect growth regulators (IGRs). These chemicals especially offer a good potential for controlling manure-breeding flies (CHAMBERLAIN, 19 75). In recent years these drugs have been studied intensively in the view that most of them are not toxic for the environment and are very effective in rather low concentrations (HARRIS, FRAZER and YOUNGER, 1973; WRIGHT, 1974; MILLER and UEBEL, 1974; WRIGHT, CAMPBELL and OEHLER, 1974). Cyromazine (CGA72662) has been developed as the most effective compound of the triazines by CIBA-GEIGY Limited. Its mechanism of toxicity is not understood clearly. Studies on the effect of CGA-72 662 on in vitro chitin synthesis showed that cyromazine acts as a chitin synthesis inhibitor, though this effect is less pronounced active than that of diflubenzuron (MILLER et al. , 1981). On the other hand, it was demonstrated in histological studies on the effect of this chemical that there was no interference with normal cuticle deposition (TURNBULL, PYLIOTIS and HOWELLS, 1980; AWAD andMULLA, 1984). We know that this new IGR interfered with the normal development of fly larvae. Ovicidal or chemosterilant effects could not be observed (HALL and FOEHSE, 1980). R R Cyromazine and its products (Larvadex , Neporex ) have been evaluated against several fly species in laboratory and field trials. It was shown that this chemical is very effective against 7 7
