Augmentative release of parasitoids has been an important component of integrated insect management for stored product protection. Understanding the effect of different temperatures on the growth and development of parasitoids is in favor of mass rearing of parasitoids. Habrobracon hebetor Say (Hymenoptera: Braconidae) is a highly cosmopolitan, gregarious ecto-parasitoid of a variety of Lepidopterous larvae. Thus, the growth and development of H. hebetor reared on Ephestia elutella (Hübner) (Lepidoptera: Pyralidae) larvae were investigated at 15, 20, 25, 30, and 35 °C. Habrobracon hebetor could complete growth and development, and the developmental duration decreased with increasing temperature at 15, 20, 25, 30, and 35 °C. The development threshold temperatures of H. hebetor eggs, larvae, pupae, and egg-to-adult stages were 13.89, 6.39, 9.24, and 9.29 °C, and the effective accumulated temperatures were 23.33, 46.40, 142.68, and 240.31 °C·d, respectively. The total number of eggs laid by H. hebetor, the hatching rate of H. hebetor eggs, and the percentage of female offspring reached the maximum of 192.39, 83.89%, and 74.04% at 30 °C, respectively. There was no significant difference in pupal survival rate in the temperature range of 15 °C to 35 °C. At 30 °C, the pre-oviposition duration of H. hebetor was the shortest (0.87 d). Therefore, the optimal rearing temperature of H. hebetor was 30 °C. The present results are useful for the large-scale rearing of H. hebetor using E. elutella larvae as hosts and effectively implementing the biological control of stored-product insects.

Biological control by releasing a large number of parasitoids has been an effective strategy for coping with stored-product pest insects. Habrobracon hebetor (Say) (Hymenoptera: Braconidae) has strong control capabilities over Lepidoptera pests. Exploring the optimum storage temperature, life stage, and cold storage period of H. hebetor is of great importance for the utilization of parasitoids. In this context, the survival, parasitism, and fecundity of H. hebetor were evaluated after 10, 20, 30, 40, 50, and 60 d of exposure at −5, 0, 5, 10, and 15 °C for H. hebetor eggs, larvae, pupae, and adults, and the survival, parasitism, and fecundity of H. hebetor individuals that had been maintained at normal rearing condition were taken as a control. The cold exposure duration dramatically affected the development and survival of eggs, larvae, and pupae of H. hebetor, regardless of the temperatures tested. Habrobracon hebetor eggs, larvae, and pupae failed to develop into the next life stage at −5, 0, and 5 °C. Habrobracon hebetor eggs, larvae, pupae, and adults failed to survive after 10 d exposure at −5 and 0 °C. The parasitism rate, fecundity and oviposition duration of H. hebetor adults that originated from eggs, larvae, pupae, and adults after different cold storage durations markedly decreased with increasing cold storage duration. The highest parasitism rate of adults was 34.12% after exposure at 5 °C for 10 d, which was not significantly different from the control (31.86%). The maximum level of egg production of H. hebetor adults developed from initial larvae exposed at 15 °C for 10 d and 20 d were 344.67 and 340.67 eggs/female, respectively, which were not significantly different from the control (392.00 eggs/female). When H. hebetor larvae were stored at 15 °C for 10 and 60 d, the oviposition duration of newly emerged adults reached the maximum and minimum levels recorded, with 17.00 and 0.83 d, respectively. These results provide empirical support for the large-scale production and storage of H. hebetor.

Screen meshes made of nylon are used in windows, doors, and vents to prevent stored product insects from entering grain storage and food processing spaces in China. To evaluate the physical passage of stored-product insects through screen meshes, seven major stored-product insects were allowed to move through a series of screen meshes with different sizes of mesh openings (0.90, 0.70, 0.50, 0.40, 0.30, 0.20, 0.15, 0.12, and 0.10 mm). The test insects were adults and newly hatched larvae (1st instar) of Tribolium castaneum (Herbst), Oryzaephilus surinamensis (Linnaeus), and Lasioderma serricorne (Fabricius), adults of Sitophilus zeamais Motschlusky, Sitophilus oryzae (Linnaeus), Cryptolestes ferrugineus (Stephens) and Liposcelis bostrychophila (Bodonnel). The test insects were respectively placed on a series of screen meshes for 24, 48, and 168 h, and the passage rates of stored-product insects through different sizes of screen meshes were recorded. The screen mesh size significantly affected the passage rate of adults and newly hatched larvae of the test insects, and the passage rate of adults and newly hatched larvae increased with increasing treatment time. The adults of T. castaneum, S. zeamais, S. oryzae, and L. serricorne were completely excluded by ≤ 0.70 mm screen meshes. The adults of O. surinamensis and C. ferrugineus were completely excluded by ≤ 0.30 and 0.15 mm screen meshes, respectively. The adults of L. bostrychophila were completely excluded by ≤ 0.15 mm screen meshes. The newly hatched larvae of L. serricorne and T. castaneum were completely excluded by ≤ 0.12 mm screen meshes, and the newly hatched larvae of O. surinamensis were completely excluded by ≤ 0.15 mm screen meshes. The aim of this study is to provide guidance on the selection of mesh aperture sizes for nylon screens used in doors, windows, and ventilation openings, in order to effectively prevent the entry of pests and storage insects into grain storage and food processing facilities.