Cross-resistance between flucycloxuron,clofentezine and hexythiazox in Panonychus ulmi (fruit tree red spider mite)

Between 1988 and 1992, 26 strains of Panonychus ulmi (fruit tree red spider mite) were collected from fields in which control failures had been observed with the acaricides clofentezine, hexythiazox or flucycloxuron.Strains were tested for susceptibility using a standardized laboratory method, to check whether control failure was due to (cross-) resistance. Classification of field populations was on the basis of their observed tolerance distribution as measured by estimates of the logLC₅₀ () and the inverse of the slope of the probit regression line () respectively. In the analyses we present classifications based on % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\\hat \mu \] alone, and on % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\\hat \mu \] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbaK% aaaaa!36AA!\\hat \sigma \].Regression analyses are used to predict the activity of the new compound flucycloxuron ((F)), in situations where activities of clofentezine ((C)) and/or hexythiazox ((H)) were known. There is strong evidence of cross-resistance between all three compounds. The best predictor of (F) is given by the multiple regression on (C) and (H) constrained to pass through the mean % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGGipm0dc9vqaqpepu0xbbG8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafqiVd0MbaK% aaaaa!369D!\\hat \mu \] of the susceptible strain (R²=0.81). It can be also predicted from (C) alone (R²=0.738), or from (H) alone (R²=0.737). The squared correlation between (C) and (H) was R²=0.62.