Naturally Occurring Trichogramma Species in an Apple Orchard in Hungary

The genus Trichogramma Westwood (Hymenoptera: Trichogrammatidae) includes insect egg parasitoids widely used worldwide as biological control agent of pests. The success of these parasitoids in pest management depends, among other factors, on their adaptation to the climatic conditions of the release area, particularly temperature. This study aimed to identify the Trichogramma species naturally occurring in Hungary. Parasitism was observed by trapping Trichogramma spp. individuals using bait cards containing Sitotroga ceraella eggs (provided by the AMW company) in apple orchard between July 8, 2024, and September 30, 2024. We evaluated the relationship between several variables – the rate of cards with observed parasitism, the parasitism rate, the number of host eggs and the hatching rate – and the time of release, the age of the host eggs and meteorological factors. We found that the parasitism rate significantly depends on the time of release. Pearson's correlation coefficients indicated that temperature parameters (average minimum, maximum and the mean temperatures during the exposure period of the cards) are significantly and negatively correlated with both parasitism rate and number of parasitised eggs. Air pressure showed a significant positive correlation with the number of parasitised eggs. The naturally occurring egg parasitoid species was identified as T. evanescens. These results suggest that these parasitoids are well adapted to the local climate and can be considered as candidates for pest management programs in Hungary and in other countries with a temperate continental climate.