Sublethal Effects of Four Pesticides on Paedogenetic Larvae of the Cecidomyiidae

Abstract

The sublethal effects of four pesticides on paedogenetic larvae of the Cecidomyiidae were investigated in sterile culture. With Heteropezapygmaea: -(a) diazinon at 0.2 ppm and above in the agar medium produced an ,,all or nothing" response where most larvae lost locomotory co-ordination and did not feed, but on transference to an untreated culture many recovered and reproduced; (b) y HCH reduced activity, hemipupal size and fecundity in proportion to dosage; (c) quinomethionate reduced hemipupal size but the number of young increased from a mean of 12 for untreated parents to 15.5 at 0.32 ppm; (d) diflubenzuron induced one larva.to produce a previously unrecorded second instar and the evolutionary significance of this is discussed. The effect of diflubenzuron on larvae of Mycophila speyeri was twofold: a reduction in fecundity of the parents and an increase in pupa-larva production.

Effects of Methoprene and Permethrin on Paedogenetic Larvae of <I>Heteropeza pygmaea</I> and <I>Mycophila speyeri</I> (Diptera: Cecidomyiidae)

“…Reduced locomotion was observed at high rates of methoprene and at all rates of permethrin. In experiments with a number of pesticides, White (1977) observed two general effects on feeding and locomotion of H. pygmaea larvae: (1) an Ôall or nothingÕ effect, whereby similarly treated larvae either had no locomotory coordination and could not feed or develop; or, alternatively, moved and fed normally and developed to hemipupae; or (2) a gradual reduction in general feeding and locomotion in proportion to dosage, with all larvae developing to the hemipupal stage. In these experiments, where an effect was demonstrated, it was evident that the latter effect was occurring with M. speyeri but with the added beneÞt of signiÞcant mortality at high rates of permethrin.…”

“…Cecidomyiids were cultured using the method described by White (1977). In brief, cecidomyiids were fed on the basidiomycete fungus Chondrostereum purpureum (Fr.)…”

“…Even those that used to be available to the grower, diazinon and gamma hexachlorocyclohexane, although able to control M. speyeri larvae, affected H. pygmaea larvae only by depressing population growth (Hussey et al 1960), implying sublethal action. Earlier work by the author (White 1977) described a laboratory-based method to elucidate insecticidal effects on paedogenetic cecidomyiid larvae. Neither of these chemicals killed H. pygmaea larvae at concentrations up to 0.88 and 4.8 g/g of media, respectively, but caused various sublethal effects.…”

Effects of the paedogenetic mushroom cecid, Heteropeza pygmaea (Diptera:Cecidomyiidae) on cropping of the cultivated mushroom (Agaricus bisporus)

“…H. pygmaea larvae were mass-reared on an artificial medium as described by White (1977). After being washed off the medium into a Petri dish, known numbers of larvae were pipetted into small glass vials in the laboratory, one vial for each treatment.…”