关键词:

棉铃虫齿唇姬蜂, 低温贮藏, 羽化率, 性比, 寄生率

Abstract:

Campoletis chlorideae is an important dominant species of natural enemies in China. The development of C. chlorideae as a commercial biological control agent requires reliable storage techniques that can extend its shelf life without compromising parasitoid quality, thereby facilitating large-scale production, transportation, and precisely timed field releases. To determine the relationship between storage temperature, developmental progression, and post-storage biological quality of C. chlorideae, the developmental morphology of each stage of the pupal stage was determined through timed physiological dissections of C. chlorideae grown at room temperature. Then, 1-day-old pre-pupal cocoons were stored at 8, 12, 15, 20, and 25 ℃, and storage duration, emergence rate, adult reproductive capacity, and parasitism ability were quantified. Development of C. chlorideae was progressively prolonged as temperature decreased, with the developmental period extending to as long as 58.65 d at the lowest temperature tested. Based on the relationship between developmental rate and temperature, the lower developmental threshold for the cocoon stage, from prepupa to adult emergence, was estimated to be 7.94  ℃, and the corresponding thermal constant was 112.46 (d·℃). The systematic assessment of its adaptability and pest control efficacy under different storage temperatures showed storage at 20 ℃  extended the viable storage duration by 4.65 d compared with the standard rearing temperature of 25 ℃, reaching up to 10.85 d. Importantly, storage at 20 ℃caused no significant adverse effects on adult emergence rate, proportion of females, mating rate, egg load, ovarian development, parasitization behavior, parasitization capacity, or fecundity. In contrast, storage at lower temperatures of 15, 12, and 8 ℃ adversely affected adult emergence, reproduction, and parasitization to varying degrees, with these detrimental effects becoming progressively more pronounced as temperature decreased. Although storage at 8 ℃resulted in the greatest extension of the storage period, parasitoid quality deteriorated substantially under this condition. The adult emergence rate declined to only 13.57%, and the 7-d survival rate of emerged adults was only 56.52%. Moreover, the proportion of females increased to 87.24%, representing a 44.54% increase relative to the normal sex ratio and indicating a severe distortion of the offspring sex ratio. Males emerging after storage at 8 ℃exhibited an apparent loss of courtship ability and failed to mate successfully with females, thereby greatly impairing successful reproduction and potentially preventing normal population renewal. These findings provide a theoretical basis and practical technical reference for optimizing low-temperature storage protocols for C. chlorideae, improving the efficiency and quality control of parasitoid storage and mass production, and enabling synchronized and precisely timed field releases of this important biological control agent.

Key words:

Campoletis chlorideae, low-temperature store, emergence rate, sex ratio, parasitism rate