Biological characteristics of the native parasitoid Bracon (Habrobracon) didemie against Tuta absoluta under laboratory conditions

Abstract: The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a
major pest causing economic losses in tomato production in Türkiye and worldwide. Although chemical control remains the primary management method, its limitations were demonstrated. Bracon (Habrobracon) didemie Beyarslan (Hymenoptera: Braconidae) has been identified as a promising candidate for biological control of T. absoluta. This study investigated the biological characteristics of B. (H.) didemie under controlled laboratory conditions (25 ± 1 °C, 70 ± 5 % humidity, 16:8 light-dark). The preferred larval stage of T. absoluta for parasitism by B. (H.) didemie was determined using choice and no-choice experiments. In no-choice experiments, individual larval stages (1st, 2nd, 3rd, and 4th instars) were separately exposed to parasitoid females, while in choice trials, all larval stages were presented simultaneously. To determine the immature development time, female parasitoids were allowed to oviposit on 4th instar larvae for 5 hours. The development time of immature stages were subsequently monitored. In nochoice experiment, female B. (H.) didemie induced mortality in all larval stages of T. absoluta, with the rates increasing with larval stages: 7 % in the 1st instar, 30.8 % in the 2nd instar, 36.2 % in the 3rd instar, and 37 % in the 4th instar. No oviposition was recorded in the 1st instar, while the average number of eggs laid per larva increased progressively in later stages (0.26 in the 2nd, 0.8 in the 3rd, and 1.53 in the 4th instar). In choice experiments, mortality was highest in the 4th instar (31.6 %), with minimal oviposition in older stages (0.06 in the 3rd, and 0.4 in the 4th instar). The total immature development time of B. (H.) didemie varied with sex, with females completing development in 11.23 days and males in 10.51 days. This study highlights key aspects of B. (H.) didemie’s biology and its potential as a biological control agent. Further research is needed to evaluate its efficacy in laboratory and field conditions.