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.

This study presents the findings of on-farm trials conducted in Hungary between 2023 and 2025, evaluating the efficacy of inundative Trichogramma releases against the European corn borer (ECB) and the cotton bollworm (CBW). The research assessed three Trichogramma preparations, including solo T. brassicae (TB) and two species mixtures: (1) T. dendrolimi, T. cacoeciae, and T. brassicae (TSM1) and (2) T. brassicae and T. pintoi (TSM2). The timing of the releases was synchronized with pest swarming and maize phenology. The efficacy of Trichogramma-based biological control was assessed by comparing the number of damaged plants and the number of pest larvae detected in treated and untreated plots. Statistical analyses revealed a significant association between the release of parasitoids and a reduction in pest damage. The efficacy of the Trichogramma releases was determined using Abbott’s formula. In our research, the following pattern emerged: (1) medium efficacy (ranging from 40% to 68.2%) occurred under low pest pressure and optimal weather conditions; (2) low efficacy (35.5% and 33.3%) occurred under medium pest pressure and suboptimal climatic conditions; and (3) no efficacy occurred under high pest abundance combined with unfavorable weather. Our findings suggest that Trichogramma-based products can serve as complementary components of Integrated Pest Management (IPM); however, they also emphasize that parasitism by Trichogramma wasps is influenced by several factors, such as climatic conditions and pest abundance, indicating that additional plant protection treatments may be necessary, for example, under high pest pressure and/or suboptimal climatic conditions.