The effect of weather on frit fly (Oscinella frit L.) and its predators.
Abstract
The following is virtually the author's summary of this account of observations in southern England. Weather at the critical times of oviposition, larval penetration and emergence determines the numbers of Oscinella frit (L.) on oats [cf. preceding abstract]. In unfavourable weather, females shelter in spaces in the soil. Ground-living predators are also less active during cold, wet weather. Predation occurs only to a small extent on exposed stages of the Chloropid. Small non-specific egg feeders such as Bembidion lampros (Hbst.), Trechus quadristriatus (Schr.), Tachyporus spp., and the mite Pergamasus longicornis (Bart.) may destroy eggs. All stages of the: panicle generation [cf. RAE A 47 219] may be preyed on by Anthocoris nemorum (L.). Adults of all generations may be caught by Dipterous predators normally present in the habitat. The commonest seen were Tachydromia spp., Scatophaga stercoraria[Scathophaga stercoraria] (L.) and Medeterus truncorum Mg. When the weather is good for oviposition, the combined activity of predators and parasites is not enough to-protect late-sown oats. Spraying twice with parathion in the 2-3-leaf stage is, effective; alternatively, the sprays can be applied to the soil before the crop is sown.