Laboratory evaluation of the efficacy of the juvenile hormone analog fenoxycarb for controlling the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae)

Hicks, Barry J. (1992) Laboratory evaluation of the efficacy of the juvenile hormone analog fenoxycarb for controlling the eastern spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae). Masters thesis, Memorial University of Newfoundland.

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Abstract

Topical application of the JHA, Fenoxycarb, to various developmental stages of Choristoneura fumiferana (Clms.) showed it to be an extremely promising compound for development as a control agent. Eggs 0 to 24 hr-old were most sensitive; eggs 48 to 12 hr-old and fifth instar larvae were less sensitive while third instar larvae were refractory. -- Treatment of fifth instar larvae produced morphogenetic effects such as larval-pupal intermediates, supernumerary moulting and deformed pupae and adults. -- Failure of hatching was the most striking effect when C. fumiferana eggs were treated with Fenoxycarb. Embryonic development was blocked by the compound at an early stage, or completed by embryos developing from the same egg mass. Observations of deformed unhatched embryos and some that completed embryogenesis, but died during hatching while partially emerged, suggests that Fenoxycarb disrupted the muscular/exoskeletal system that is needed to allow eclosion from the egg. Choristoneura fumiferana eggs treated with Fenoxycarb produced numerous abnormalities in the developing embryos such as miss-orientation and absence of walking appendages. -- Treated eggs that, nevertheless, hatched developed increased mortality in post-embryonic development. Eggs that were treated with Fenoxycarb and reared to the adult stage exhibited increased mortality prior to or during the overwinter diapause stage (hibernacula). The overall mortality to the adult stage was significantly higher in treated insects than in controls. -- Temperature and relative humidity altered the efficacy of Fenoxycarb toward early eggs of C. fumiferana. Treated and control eggs were not affected by photoperiod. The optimum temperature to achieve greatest effects of the compound on eggs was 15°C. Relative humidity only became an influencing factor when the temperature was at 20°C. At that temperature a relative humidity of 60% was shown to be most effective.

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