The Temperature-Dependent Functional Response and Mutual Interference of Cyanopterus ninghais (Hymenoptera: Braconidae) Parasitizing Monochamus alternatus (Coleoptera: Cerambycidae)

Abstract

Cyanopterus ninghais (Hymenoptera: Braconidae) is a newly discovered parasitoid on the 3rd-5th instar larvae of the Japanese pine sawyer, Monochamus alternatus (Coleoptera: Cerambycidae). We investigated the functional response of C. ninghais at three temperatures (20, 25, and 30 °C) and examined mutual interference. Results showed that C. ninghais had a Holling Type II functional response at all temperatures. By increasing the density of the M. alternatus larvae, the number of parasitized larvae increased until a maximum was reached. The parasitoid was most effective (a′/Th) at 30 °C (0.270) and an individual female wasp’s attack rate (a′) was 0.158, the handling time (Th) was 0.587, and the maximum theoretical parasitization rate per day (T/Th) was 11.927. However, the per capita parasitized level and per capita searching efficiency decreased significantly when the parasitoid density ranged from one to five. These findings suggest that intraspecific mutual interference and competition occur when multiple females search for a host in the same area. This study demonstrates that C. ninghais serves as an effective biocontrol agent, displaying strong control capabilities against M. alternatus larvae, with the potential for further development in the context of biological pest management targeting M. alternatus.