Vol.12_No.2 - Pesticide Alternatives Lab - Michigan State University

Spring 2003 Resistant Pest Management Newsletter Vol. 12, No.2The results support the excellent local larvicideactivity of the virus-based products, spinosad andthiacloprid, whose efficacy was superior, even if not ina statistically significant way, to azinphos-methyl.Instead, the average damage recorded in the plotstreated by indoxacarb was greater than with thecompared insecticides, thus not ensuring sufficientprotection (10.7% damage) (Fig. 6).In Trentino the field experiments were carried outin different years and with different CM populationdensities. The insecticides evaluated were spinosad,methoxyfenozide, thiacloprid, and indoxacarb ascompared with chlorpyriphos. Each experimentalregime comprised a treatment with an IGR at the startof egg-laying. Different insecticides were appliedaccording to the intensity of egg-laying recorded byscouting in the orchard. Only chlorpirifos was appliedcuratively, 3 times in high-pressure years and 2 timesin low-pressure years. In this context, spinosad andthiacloprid resulted to be as effective asmethoxyfenozide and indoxacarb (Fig. 7).insecticide resistance was first detected. The firstobjective to be achieved in the farms with high fruitdamages was to reduce such damage within acceptablelevels. Hence, plant protection strategies weredeveloped that provided for integration betweenbiological and chemical products. As regards the IGRs,diflubenzuron was substituted by flufenoxuron, whichshowed it could maintain a good degree of efficacy inpopulations resistant to this class of product. The use offlufenoxuron on pear orchards, however, is notadvisable because of its secondary effects on psillapopulations.Chlorpyriphos, because of its demonstrated lack ofcross-resistance with the azinphos-resistant strain, wascritical in managing resistance in both regions. The useof chlorpyriphos has to be limited due to its hightoxicity for humans and its negative side effects onbeneficial organisms. The reduction of organophosphatesuse has for the moment been made possibleby the use of the granulosis virus that demonstrates anefficacy equal to or superior to chemical products.Hence, it is now being widely employed in Emilia-Romagna. Moreover, in this region CM-GV and theapplication of mating disruption are the main strategiessuggested for orchards with low CM population levelsfor the resistance management.In Trentino, on the other hand, as the levels of theCM population are generally quite low, the wideapplication of mating disruption allowed pesticideresistance to be successfully managed. Furthermore,according to the results of the field trials carried out inthese two fruit-growing areas, it has been shown thatnew pesticides, such as spinosad and thiacloprid, couldbe introduced into the IRM programs. Nevertheless,attention should be paid to their possible negative sideeffectsagainst the beneficial organisms controlling thepear-psilla populations.REFERENCESBoselli M., Vergnani S.(2001). Attività di alcuni insetticidi nei confrontidella prima generazione di Cydia pomonella L. Informatorefitopatologico. 6: 40-46.Ioriatti C., Bouvier J.C. (2000). La resistenza agli insetticidi; il caso dellacarpocapsa (Cydia pomonella L.). Informatore Fitopatologico 9: 5-10.Ioriatti C., Bouvier J.C., Butturini A., Cornale R., Tiso R. (2003).Carpocapsa: la situazione della resistenza ad azinphos methyl ediflubenzuron in Trentino ed Emilia-Romagna. InformatoreFitopatologico. 1: 53-60.Sauphanor B., Brosse V., Monier C., Bouvier J.C. (1998). Differentialovicidal and larvicidal resistance to benzoylureas in the codlingmoth, Cydia pomonella. Entomol. exp. appl., 88: 247-253.C.IoriattiISMAAS.Michele a/A TrentoItalyCONCLUSIONS Technical recommendation IRMstrategies were applied in both regions after someM.BoselliServizio FitosanitarioRegione Emilia-Romagna, BolognaItaly68