THE IMPACT OF FUNGICIDES ON THE MORTALITY OF THE PREDATORY BUG MACROLOPHUS PYGMAEUS

Abstract

The integrated protection strategy for solanaceous crops in greenhouses involves a combination of measures that include the use of beneficial insects –specifically the predatory bug Macrolophus pygmaeus – for pest control, as well as pesticides for managing plant diseases. This article presents the results of an assessment of four fungicides and their effects on the mortality of Macrolophus pygmaeus adults and nymphs under laboratory conditions. The treatments included copper sulfate, bupirimate, propamocarb combined with aluminium fosetyl, and the biological agent Trichoderma harzianum. The aim of this study was to provide recommendations for the application of fungicides in production and laboratory settings, based on the observed lethal effects on the beneficial predator Macrolophus pygmaeus. According to the experimental results, the safest fungicides for Macrolophus pygmaeus were the following. The biological product based on Trichoderma harzianum showed the lowest mortality rates: on day 7 after treatment, nymph mortality reached 18.4%, while adult mortality was 19.4%. A similar level of safety was observed for the formulation containing propamocarb hydrochloride and aluminium fosetyl, which caused 18.4% mortality in fifth-instar nymphs and 19.8% mortality in adults. These results allow both products to be classified as non-harmful and suitable for use under production conditions in biolaboratories and greenhouses, even when applied by contact. The active ingredient bupirimate caused 19.8% adult mortality and 46.8% mortality in fifth-instar nymphs on day 7 after treatment. This indicates moderate toxicity for younger developmental stages during contact exposure. Therefore, its application should be used with caution in production, or potentially excluded, to reduce the risk of population loss of the beneficial predator Macrolophus pygmaeus. The mineral fungicide copper sulfate demonstrated a pronounced negative effect on Macrolophus pygmaeus. By day 7 after treatment, adult mortality reached 31%, while mortality of fifth-instar nymphs increased to 51.6%, with cumulative lethality continuing to rise over time. This indicates a prolonged toxic effect of the fungicide after application and the absence of degradation of the active substance during exposure. Its use is therefore considered highly toxic to beneficial insects under contact application and shows an insecticidal effect, meaning it must be applied with extreme caution. In summary, the findings classify Trichoderma harzianum and propamocarb + aluminium fosetyl as compatible with Macrolophus pygmaeus, whereas bupirimate and copper sulfate should be used with caution or excluded from biological protection programs.