Variation in response to insecticides in two species of univoltine leafrollers (Lepidoptera: Tortricidae)

Abstract

Populations of fruittree leafroller, Archips argyrospila (Walker), and European leafroller, Archips rosana L., were obtained from eight sites in the Okanagan Valley, British Columbia, and assayed for their responses to five insecticides using a leaf-disk bioassay and neonate larvae. Lethal concentration ratios (LCR values) were calculated for all populations compared with the most susceptible strain, and significant variation was detected in both species. LCR values ranged from 1.04 to 9.06 for azinphosmethyl, from 1.29 to 53.15 for tebufenozide (Confirm®), from 1.85 to 24.69 for methoxyfenozide (Intrepid®), from 1.59 to 2291.4 for indoxacarb (Avaunt®), and from 1.92 to 1.98 for spinosad (Success®). Methoxy fenozide was approximately 100-fold more toxic to neonate leafrollers than was tebufenozide, and spinosad was the most toxic of all materials tested. Correlation analysis indicated that there was cross-resistance between azinphosmethyl and tebufenozide. At the LC50 level, the responses of the two species were not significantly different for each insecticide. Analysis of equivalency and parallelism of dose-response lines revealed that A. argyrospila and A. rosana had equivalent responses to azinphosmethyl. LC50 values for the response of A. argyrospila to azinphosmethyl were not different from values obtained almost 20 years earlier. Cross-resistance between azinphosmethyl and tebufenozide suggests that resistance management for these two species of univoltine leafrollers should not include rotation of azinphosmethyl and benzoylhydrazine insect-growth regulators. The high level of resistance to indoxacarb found in one population indicates that baseline tolerance screening is desirable before indoxacarb is introduced for use in Canadian orchards.

Susceptibility of Leafrollers (Lepidoptera: Tortricidae) from Organic and Conventional Orchards to Azinphosmethyl, Spinosad, and <I>Bacillus thuringiensis</I>

“…Smirle et al (2002) also demonstrated cross-resistance between azinphosmethyl and the benzoylhydrazine growth regulators tebufenozide (ConÞrm, Dow AgroSciences, Indianapolis, IN) and methoxyfenozide (Intrepid, Dow AgroSciences), insecticides with a short history of usage in British Columbia in the case of tebufenozide (registered in 1996) and no prior usage at all in the case of methoxyfenozide. Similar Þndings have been reported for populations of univoltine leafrollers (Archips argyrospila [Walker] and A. rosana L.) collected from British Columbian apple orchards (Smirle et al 2003).…”

Cross‐resistance patterns and fitness in fufenozide‐resistant diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

“…A similar conclusion was reached for C. rosaceana 19, 30 and C. pomonella (L.) 31, 32. Smirle et al 33, 34 observed that populations of fruit tree leafroller, Archips argyrospila (Walker), European leafroller, Archips rosana L., and obliquebanded leafroller, C. rosaceana , all had cross‐resistance between azinphosmethyl and tebufenozide. These differences may be influenced by the histories of insecticide exposure in the field.…”

Diversity of insecticide resistance mechanisms and spectrum in European populations of the codling moth, Cydia pomonella

“…This supports cross‐resistance between azinphos‐methyl and tebufenozide, which has been used since 1997 to control codling moth in Switzerland. Such cross‐resistance between azinphos‐methyl and tebufenozide has also been recorded in other tortricid species such as Planotortrix octo (Walker)46 and Choristoneura rosaceana (Harris) 47, 48. A second example concerns the reduced susceptibility of diapausing larvae from each of the five studied countries to recent insecticides with novel modes of action (thiacloprid and spinosad) that are not or were only recently registered against this species.…”