T. remus is an important egg parasitoid of S. frugiperda, serving as a significant role in its biological control. This study systematically examined the host discrimination behavior of T. remus. The parasitic process comprises several distinct behavioral stages: host searching, antennal tapping and examination, ovipositor probing, “8”-shaped marking, and grooming. Following successful oviposition, females perform a characteristic “8”-shaped marking on the host egg surface with their ovipositor, which deters conspecific females from parasitizing the same host. T. remus exhibited a pronounced ability to discriminate parasitized hosts, utilizing both antennae and ovipositor to avoid superparasitism. As host density increased, the searching time of T. remus decreased while the parasitism rate increased, eventually stabilizing. Parasitic discrimination was significantly influenced by oviposition experience: experienced females effectively recognized marked host eggs across a temperature range of 16 to 36 °C and time intervals of 0 to 12 h post oviposition. In contrast, naive females exhibited discrimination ability only at lower temperature (16 °C) and immediately following oviposition (0 h). These findings deepen the understanding of the behavioral ecology of T. remus and provide a crucial theoretical basis for its efficient application in the biological control of S. frugiperda.

Mating behavior is critical for the reproduction of Hermetia illucens, but the effects of multiple mating on female fecundity remain poorly understood. This study systematically investigated mating and oviposition behavior, mating diel rhythm, mating frequency distribution, and the effects of different mating histories on female egg production and the egg hatching rate in H. illucens under controlled conditions. The behavioral sequence of courtship, copulation, and oviposition was described. To evaluate the reproductive consequences of mating frequency, females with different pre-pairing mating histories (unmated vs. once-mated) were paired with males with different mating histories (unmated vs. once-mated vs. twice-mated), and the egg mass per female and egg hatching rate were compared among treatments. Mating peaked on day 2 after emergence (77.3%), with two daily activity peaks at 09:00–11:59 and 14:00–16:59. Most individuals mated once or twice, with a maximum of four matings. Notably, 30.0% of males remained unmated, a proportion significantly higher than that of unmated females (10.6%). Mating history had no significant effect on egg mass per female or the egg hatching rate (p > 0.05): neither female mating frequency (unmated vs. previously mated once) nor male mating frequency (unmated vs. previously mated once vs. previously mated twice) significantly affected these reproductive outcomes. These results indicate that one successful mating can meet female fertilization requirements, with no additional reproductive advantage from multiple mating under unfed, single-oviposition-event conditions. The higher unmated rate in males than in females suggests that the proportion of males in production colonies can be appropriately reduced without compromising reproductive efficiency under the tested cage conditions; validation under larger-scale, higher-density production systems is still required.

Two new species of the genus Encarsia Förster (Hymenoptera: Aphelinidae), E. cinnamomi Wang & Huang, sp.n. and E. ophiopogonis Wang & Huang, sp.n., are described and illustrated from Fujian, China. The mitochondrial genomes of these two new species and E. diaspidicola are sequenced (14,049 bp, 14,746 bp and 14,849 bp, respectively), both showing a strong A + T bias (84.1%, 84.7% and 84.8% respectively). We infer the phylogenies of several Encarsia species of Aphelinidae and other family of Chalcidoidea based on PCG123 datasets using Bayesian inference (BI) and maximum likelihood (ML) methods. ML and BI analysis both support Aphelinidae formed a sister group to Torymidae.