Effect of temperature on development, survival, and fecundity of Microplitis manilae (Hymenoptera: Braconidae)

Abstract

Microplitis manilae Ashmead (Hymenoptera: Braconidae), a larval parasitoid, is a potential biological control agent of both Spodoptera exigua (Hübner) and Spodoptera litura (F.) (Lepidoptera: Noctuidae). Aspects of the climatic requirements for development, including survival, longevity, and fecundity of M. manilae were studied at six constant temperature regimes (17, 20, 23, 26, 29, and 32°C) in the laboratory. The results showed that developmental duration for egg, larva, pupa, and the entire immature stages shortened in response to temperature increasing from 17 to 32°C. Survival rates of different developmental stages were higher at 20-29°C than at other temperatures. Longevity of M. manilae adults shortened with increasing temperature. The maximum fecundity of M. manilae female equaled 261.0 eggs/female at 26°C. Minimum threshold temperature and effective accumulated temperature for completing a generation of M. manilae were 11.04°C and 205.98 degrees-days, respectively. Both intrinsic rate of increase (r) and finite rate of increase (λ) of M. manilae did not differ between 26 and 29°C, but those were significantly higher at 26 and 29°C than at any other temperatures. The highest net reproduction rate (r(0)) was observed at 26°C, with the value of 97.77, but the lowest was 11.79 at 32°C. These results suggest that the parasitoid is well adapted to temperate and subtropical climates, which implies a significant potential for using M. manilae to control S. exigua because most of areas occupied by these two pests belong to temperate and subtropical regions in southeastern Asia.