Sequential testing scheme for the assessment of the side-effects of plant protection products on the predatory bug Orius laevigatus

Abstract

This paper describes a number of test methods, to beused in a sequential scheme, for testing the side-effects ofplant protection products on anthocorid bugs. Orius laevigatuswas used as test species. A `worst case' laboratory method wasdeveloped for evaluating the effect on mortality of the nymphsand the reproduction of the adults. An extended laboratory methodgives information on the effect of pesticides on adults undermore natural conditions. A semi-field test is executed in smallplots under field (glasshouse) conditions. Finally a field testsimulates the conditions in a commercial crop. For harmfulchemicals, both a laboratory and a semi-field persistence testwas developed to determine the safety period after which thepredatory bugs can be re-introduced in the greenhouse withoutbeing adversely affected. The total result of this sequentialscheme should indicate whether, and with what restrictions, aparticular pesticide can be implemented in IPM programs in whichO. laevigatus is used for control of western flower thrips(Frankliniella occidentalis). Twenty-two pesticides were testedincluding five fungicides, twelve insecticides and fiveacaricides. The fungicides captan, carbendazim, sulphur, thiram,tolylfluanid and the insecticides or acaricides pymetrozine,pyriproxyfen, tebufenozide and hexythiazox were harmless in the`worst case' laboratory test and thus did not need furthertesting. Imidacloprid, diafenthiuron, lufenuron, tebufenpyrad,abamectin, pyridaben and bifenthrin were harmful in thesemi-field test and should, in the tested concentrations, betternot be used simultaneously with the predatory bug. Theinsecticide dichlorvos was found harmful but short-lived in thepersistence test; it should be used before the introduction ofthe predatory bug O. laevigatus only when a safety period of 7days is respected. Pirimicarb was slightly toxic in thesemi-field test but short-lived. In IPM programs this aphicideshould be used at a low application frequency.