Effects of cyromazine on Leptinotarsa decemlineata
The effects of cyromazine (insect growth regulator) have been tested against Leptinotarsa decemlineata (EPPO A2 quarantine pest) in the laboratory and in the field, in Michigan (US). In the laboratory, results obtained showed that second instar larvae fed upon treated foliage died within 10 days. Fourth larval instars were less affected but showed decreased feeding and some symptoms of poisoning. Mortality of pre-pupae and pupae was high.
In the field, cyromazine sprays reduced the number of first and second instars and affected third and fourth instars by inhibiting feeding and lowering rates of pupation. Compared with the untreated control plots, cyromazine treatment reduced adult emergence from 63 fold and increased potato yield of 2 to 4.5 fold. The authors concluded that the disruption of pupation and the decrease of adult emergence make cyromazine a useful tool for control of the summer generation of Colorado beetle and that this compound could be an appropriate alternative insecticide in resistance management programmes. However, they noted that further information on its mode of action would be useful to prevent the development of resistance.
Sirota, H.M.; Grafius, E. (1994) Effects of cyromazine on larval survival, pupation, and adult emergence of Colorado potato beetle (Coleoptera: Chrysomelidae).
Journal of Economic Entomology, 87 (3), 577-582.