Acute and long‐term effects of selective insecticides onMicromus tasmaniaeWalker (Neuroptera: Hemerobiidae),Coccinella transversalisF. (Coleoptera: Coccinellidae) andNabis kinbergiiReuter (Hemiptera: Miridae)

Abstract

The impacts of six selective insecticides on three predatory insect species, Tasman's lacewing (Micromus tasmaniae), the transverse ladybird (Coccinella transversalis) and the damsel bug (Nabis kinbergii), were tested by acute and long-term bioassay. Acute bioassays measured mortality 72 h after exposure to wet sprays and dry residues, and long-term bioassays measured mortality and sublethal effects over a generation. The acute bioassays were not consistently reliable indicators of the harmfulness of insecticides that did not induce high short-term mortality. Pymetrozine caused very low mortality (Յ20%) to the larvae of C. transversalis in acute tests, but the long-term test showed that 97.6% of individuals were killed before maturity. Similarly, pirimicarb adversely affected reproduction of C. transversalis even though there was only a minor effect on short-term mortality. Imidacloprid caused low mortality (Յ20%) of M. tasmaniae in acute tests, but reproductive capacity was reduced by about two-thirds in long-term tests. Therefore, in some cases, acute bioassays were poor indicators of overall effects of insecticides on populations. Our results support previous studies by other authors that long-term mortality and sublethal effects of selective insecticides on predatory species need to be determined to facilitate their effective use alongside biological control in integrated pest management programs.

Side effects of selected insecticides on the Tuta absoluta (Lepidoptera: Gelechiidae) predators Macrolophus pygmaeus and Nesidiocoris tenuis (Hemiptera: Miridae)

“…Indoxacarb had no significant effects on female offspring in either of the predator species tested. Nevertheless, this pesticide reduced the net reproductive rate of the nabid N. kinbergii (Cole et al 2010) and the fecundity of H. axyridis (Galvan et al 2005b). …”

“…Likewise, dry pesticide residues do not cause mortality to Orius majusculus (Reuter) (Heteroptera: Anthocoridae) (Daglı and Bahşi 2009), Nabis kinbergii Reuter (Hemiptera: Nabiidae) and Coccinella transversalis F. (Coleptera: Coccinellidae). However, they induced 40% mortality in Micromus tasmaniae Walker (Neuroptera: Hemerobiidae) (Cole et al 2010). The number of offspring of M. pygmaeus females that were exposed to residues of spinosad at the end of their preimaginal development was reduced by 58%.…”

Coccinellids in Biological Control

“…However, despite observing low acute toxicity of pymetrozine to C. leonina transversalis , Cole et al (2010) found that less than 3% of exposed larvae survived to maturity. Insecticides toxic to coccinellids may also be selective by virtue of formulation or mode of application.…”

Populations of predators and parasitoids of Bemisia tabaci (Hemiptera: Aleyrodidae) after the application of eight biorational insecticides in vegetable crops

“…Growers commonly use synthetic insecticides to manage whiteflies. However, among other concerns, insecticides can have adverse effects on non‐target organisms such as natural enemies 1–4. Both lethal and sublethal effects, such as affecting behaviour, can occur on non‐target arthropods 1, 5, 6.…”