The effect of different constant temperatures on biological characteristics and life table parameters of Trichogramma bourarachae Pintureau and Babault, 1988 (Hymenoptera: Trichogrammatidae)

Abstract

Abstract Trichogramma parasitoids are highly effective biocontrol agents largely used in integrated pest management strategies for controlling lepidopterous pests. One of the key factors significantly influencing their efficacy is climatic conditions, with temperature playing a central role. Trichogramma bourarachae Pintureau and Babault (Hymenoptera: Trichogrammatidae), an arrhenotokous parasitoid commonly found in the Mediterranean region, has shown remarkable performance in managing numerous economically important lepidopterous pests. Understanding its thermal requirements holds paramount importance for optimizing rearing techniques and strategic inundative releases. In this study, we investigated the biological characteristics and life table parameters of T. bourarachae at eight constant temperatures (15, 20, 25, 30, 32, 35, 37 and 40°C) using Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs. Temperature had a significant impact on all the key life history traits of T. bourarachae, including the number of parasitized eggs, development time, emergence rate, sex ratio, progeny's longevity, and fecundity. T. bourarachae demonstrates the ability to thrive within a temperature range of 15°C to 37°C, with its optimal development and reproductive performance occurring at 32°C. Life table analysis revealed that the net reproductive rate (R0) and intrinsic rate of increase (r) peaked at 32°C. The finite rate of increase (λ) showed a positive correlation with temperature within the range of 15°C to 32°C. Generation time (T) and doubling time (DT) decreased with increasing temperature from 15°C to 37°C. These results indicate that T. bourarachae is well-adapted to high temperature conditions, positioning it as a promising candidate for controlling thermophilic lepidopteran pests in the Mediterranean region.