Effect of 3 insect growth regulators on larval development, fecundity and egg viability of the coccinelidChilocorus bipustulatus [Col.: Coccinelidae]

Abstract

The effect of 3 insect growth regulators -methoprene, diflubenzuron and RO 13-5223, on the coccinelid Chilocorus bipustulatus L. was studied in the laboratory. Feeding on Chrysomphalus aonidum (L.) or Aspidiotus hederae Vallot (Diaspididae) treated with the IGRs at the concentration of 0.025 % a.i. revealed the following : cliflubenzuron caused a complete mortality of 1St instar larvae ; methoprene and RO 13-5223 did not arrest larval development but inhibited pupation ; fecundity of sexually mature females was not affected by the 3 IGRs but egg hatch was completely inhibited ; egg viability was regained when IGR-exposed females had been transferred to an uncontaminated environment.

Effects of some insect growth regulators on natural enemies of scale insects (Hom.: Coccoidea)

“…Coccinellidae are apparently more sensitive to insect growth regulators than hymenopteran parasitoids. Peleg (1983a) showed that larvae of C. bipustulatus fed on scales treated with fenoxycarb, methoprene or diflubenzuron did not reach the adult stage. Similar results were obtained in the present study when R. cardinalis fed on I. purchasi was treated with fenoxycarb, buprofezin or pyriproxyfen.…”

“…It has been suggested that the products are only slightly harmful to beneficial arthropods, although some moderately adverse effects were recorded when coccinellids were treated with the chemicals. For example, fenoxycarb and methoprene had no adverse effects on the development and activity of several hymenopteran parasitoids of Coccidae and Diaspididae in citrus groves (Peleg, 1983a ;Peleg & Gothilf, 1980) ; however, Abd EI-Kareim et al (1988) showed that Aphytis mytilaspidis (LeBaron) (Hymenoptera : Aphelinidae) was affected by hydroprene, methoprene and kinoprene ; and the juvenoid fenarimol strongly reduced to occurrence of Encarsia berlesei (Howard) (Aphelinidae) (Darvag & Zseller, 1985). Adverse effects of insect growth regulators were recorded on immature stages of several Coccinellidae, i.e., Chilocorus bipustulatus L. (Peleg, 1983a), Stethorus punctilhtm (LeConte) (Hull et aL, 1991), Cryptolaemus montrouzieri Mulsant and Rodolia cardinalis Mulsant (Viggiani & Loia, 1991).…”

“…For example, fenoxycarb and methoprene had no adverse effects on the development and activity of several hymenopteran parasitoids of Coccidae and Diaspididae in citrus groves (Peleg, 1983a ;Peleg & Gothilf, 1980) ; however, Abd EI-Kareim et al (1988) showed that Aphytis mytilaspidis (LeBaron) (Hymenoptera : Aphelinidae) was affected by hydroprene, methoprene and kinoprene ; and the juvenoid fenarimol strongly reduced to occurrence of Encarsia berlesei (Howard) (Aphelinidae) (Darvag & Zseller, 1985). Adverse effects of insect growth regulators were recorded on immature stages of several Coccinellidae, i.e., Chilocorus bipustulatus L. (Peleg, 1983a), Stethorus punctilhtm (LeConte) (Hull et aL, 1991), Cryptolaemus montrouzieri Mulsant and Rodolia cardinalis Mulsant (Viggiani & Loia, 1991). In the case of Anthocoridae, damaging effects were recorded after application of fenoxycarb on larvae of Anthocoris nemoralis (E) (Solomon & Fitzgerald, 1990), whereas chlorfluazuron had an inhibitory effect on the moulting of Orius sp.…”

Toxicity of pesticides toHalmus chalybeus(Coleoptera: Coccinellidae) and the effect of three fungicides on their densities in a citrus orchard

“…However, several studies have recorded longer-term negative effects on ladybirds. These include increased mortality of larvae or inhibition of pupation and egg hatch (Peleg 1983;Smith & Papacek 1990;Mendel et al 1994). Further studies are needed on the longer-term effects of insect growth regulators on adult and larval H. chalybeus.…”

Various novel insecticides are less toxic to humans, more specific to key pests

“…Similar to other IGRs, the eggs and immature stages of predatory beetles, as well as lacewings, can be sensitive to diflubenzuron (Ables et al 1977). However, effects such as reduced egg hatch can be rapidly reversed when the predators enter an untreated environment (Peleg 1983). Diflubenzuron is toxic to crustaceans; however, populations recover rapidly because it rapidly dissipates in water.…”