Novel life stage targets against plum curculio, Conotrachelus nenuphar (Herbst), in apple integrated pest management

Abstract

In this study the authors employed the plant-insect-chemistry (PIC) triad to investigate two novel life stage targets against the plum curculio (PC), Conotrachelus nenuphar (Herbst), in apple integrated pest management (IPM). Laboratory treated apple bioassays were used to determine if the insect growth regulator (IGR) insecticides novaluron and tebufenozide have physiological effects on PC larvae following adult exposure. Curative activity bioassays were conducted for IGR, neonicotinoid, oxidiazine and organophosphate insecticides on PC larvae post-infestation, and fruit penetration profiles of insecticides were developed. The results revealed that novaluron exhibits activity on PC larvae via vertical transmission following exposure of mated females to treated substrate. Surface treatments of azinphos-methyl, thiacloprid and thiamethoxam to preinfested fruit resulted in significant reductions in larval emergence. For all compounds, 50% or more of the total recovered active ingredient was from apple skin, and for azinphos-methyl, indoxacarb and thiamethoxam it was greater than 80%. For azinphos-methyl, novaluron, methoxyfenozide and thiacloprid, however, active ingredient was recovered from every section of the apple, from skin to core. Implications for twenty-first century IPM are discussed.

Curative Activity of Insecticides Against Plum Curculio (Coleoptera: Curculionidae) in Tart Cherries

“…This collection of experiments serves as a Þeld validation of previously reported experiments that show plum curculio eggs and larvae are susceptible to insecticides that are used to control adults of this species (Wise et al 2007, Hoffmann et al 2008. Field residue recoveries for these compounds make strong cases for which materials have the potential to be curative agents.…”

“…The hydrophilic character of thiamethoxam may actually contribute to its penetration through the fruit ßesh where it can be later metabolized to the more lipophilic clothianidin (log P ϭ 0.7). Direct treatment with clothianidin was toxic to plum curculio eggs at much lower concentrations than thiamethoxam (Hoffmann et al 2007) and the metabolic conversion could be an important aspect of curative activity for this pair of compounds. The residue analysis techniques used for this study were unable to differentiate between clothianidin and thiamethoxam.…”

“…The fruit residues for 2007 were analyzed as surface versus subsurface fractions by using a sonication and homogenization technique (Wise et al 2007). After fruit were collected and frozen, they were weighed (Ϸ10 g per sample) and sonicated for 30 s in 60 ml of acetonitrile.…”

“…Neonicotinoids have demonstrated curative activity against larval plum curculio in apples (Malus spp.) (Wise et al 2007) and cherry fruit ßy (Yee andAlston 2006, Yee 2008).…”

Penetrative and Dislodgeable Residue Characteristics of 14C-Insecticides in Apple Fruit

“…12,13 Curative activity is the lethal action of an insecticide on a pest post-infestation from the transitory penetration of the compound into plant tissue. 6 This "curative" form of insecticide activity can serve to reduce the number of sprays to control internal fruit pests.…”