Efficacy baselines of seven insecticides against larvae of Pandemis heparana (Lepidoptera: Tortricidae)

Abstract

A diet-incorporation larval bioassay was used to evaluate the response of the leafroller Pandemis heparana (Denis and Schiffermu¨ller) to seven insecticides: tebufenozide (Mimic 23% a.i., Bayer), methoxyfenozide (Prodigy 23% a.i., Bayer), flufenoxuron (Cascade 50 DC 4.7% a.i., BASF), lufenuron (Match 5.32% a.i., Syngenta), indoxacarb (Steward WG 30% a.i., Du Pont), abamectine (Vertimec EC 1.9% a.i., Syngenta) and spinosad (Laser 44.2% a.i., Dow Agro Science). Both neonate and 12-day-old (third to fourth instar) larvae were used in the bioassay. The obtained efficacy baselines were compared with the response of the pest exposed to leaves treated with the same insecticides. The persistence of field-aged leaf residues of the seven insecticides was bioassayed on neonate larvae. Given the obtained LC 50 values in the diet-incorporation bioassays larval age was not always a significant factor affecting the response of P. heparana larvae. Differences in LC 50 values between neonate and 12-dayold larvae were not statistically significant for abamectine, tebufenozide and methoxyfenozide. Young larvae seemed to be more susceptible than older larvae to spinosad, indoxacarb and lufenuron, while flufenoxuron was more effective against 12-day-old than neonate larvae. When the larvae were exposed to the insecticides on treated leaves, all the tested compounds were less effective on older larvae than on neonates. When applied at the recommended field rates, all seven insecticides can be considered highly effective against both neonate and 12-day-old larvae of P. heparana because their security index (SI = recommended field rate/LC 90 ) always exceeded the threshold value of 1. The high persistence of insect growth inhibitors (IGIs) and moulting accelerating compounds (MACs) in the field compensates for their relatively low SI values. For this reason and given their activity against Cydia pomonella, IGIs and MACs are the most interesting insecticides for spring treatments for the combined control of both species, P. heparana and C. pomonella.

Topical, residual and ovicidal contact toxicity of three reduced‐risk insecticides against the European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), on potato

“…The rapid decline that we observed in the contact toxicity of spinosad residues as they aged from 0.5 to 24 h was somewhat unexpected considering that the persistence and efficacy of spinosad, by ingestion, on stored products are maintained for months 22, 23. The persistence of spinosad is affected by the substrate and drops by half within 22 days on field treated apple leaves 24. Indoxacarb persists on cabbage up to 14 days after treatment, and the residues will likely last 14–17 days in the field 25.…”

“…Indoxacarb persists on cabbage up to 14 days after treatment, and the residues will likely last 14–17 days in the field 25. Indoxacarb residues remain 100% effective against the Tortricidae Pandemis heparana Denis & Schiffermuller 22 days after field treatment of apple leaves 24. According to the label, indoxacarb provides excellent crop protection for 5–14 days.…”

Efficacy of Several Insecticides Alone and With Horticultural Mineral Oils on Light Brown Apple Moth (Lepidoptera: Tortricidae) Eggs

“…This approach would require a residual effect to control neonates over an extended hatching. The high persistence of IGRs in the Þeld would compensate for their low ovicidal properties (Ioriatti et al 2006), and this group warrants further investigation.…”

The molecular action of the novel insecticide, Pyridalyl

“…Significantly, no cross-resistance was observed between Pyridalyl and various currently used insecticides in Plutella xylostella or Heliothis virescens (Sakamoto et al, 2003). Pyridalyl exhibited an LD50 value against various Lepidoptera in the range of 0.77e4.48 ppm (Saito et al, 2002), that is mostly in the same range as for other insecticides (0.1e4.2, or 0.1e2800 ppm) (Pasquier and Charmillot, 2003;Ioriatti et al, 2006), depending on species, developmental stage, method of application, and compound used. Treatment of Spodoptera litura larvae with 25 ng/larva or lower caused unique symptoms after moulting, similar to scar burns at the site of treatment, that caused interference with metamorphosis (Saito et al, 2004).…”