Influence of Supplemental Protein on the Life Expectancy and Reproduction of the Chinese Citrus Fruit Fly, Bactrocera minax (Enderlein) (Tetradacus minax) (Diptera: Tephritidae).

Bactrocera minax (Enderlein) (Diptera: Tephritidae) is a major citrus pest in China, whose artificial rearing technology of the adult is not well documented to date. In this study, we tried to determine if supplementing proteins to the adult diet could result in the enhancement of some fitness parameters of B. minax. Four feeds with varying protein source were provided as F0 (water), F1 (sucrose), F2 (sucrose + yeast), and F3 (sucrose + peptone). F0 and F1 being the control, F2 and F3 were protein food types. The results showed that adults fed by F2 and F3 lived longer with 40.1 d and 32.8 d, respectively, had reduced death rates (death peaks were delayed for 5.6 d and 4.1 d, respectively), increased mating frequencies (8.1 and 5.3 per females, 4.7 and 7.3 per males, respectively), and longer mating durations (with 42 d and 34 d). In addition, females recorded an increased adult ovary development, more egg load (with 94.8 and 77.3 brood eggs per ovary) and to greater oviposition rates of 63.2 eggs/female and 19.3 eggs/female. Based on our results, protein supplements enhanced B. minax survival, mating, and fecundity. This study does not only provide basic knowledge to implement artificial rearing of B. minax, but also deepens our understanding on its physiology that could be used to enhance the management of the pest.

Effects of Water Immersion and Soil Moisture Content on Larval and Pupal Survival of Bactrocera minax (Diptera: Tephritidae).

Bactrocera minax, one of the most devastating citrus pests in Asia, has two developmental stages (mature larva and pupa) that complete their life cycle in the soil. Currently, southern China has a climate with abundant autumn rains, and soil moisture can be a major factor affecting the survival of larvae and pupae of B. minax. In the present study, we evaluated the effects of water immersion and high soil moisture content on the development of mature larvae and pupae of B. minax. When immersed in water for 1 d, 100% of mature larvae of B. minax were knocked out. When larvae were immersed for less than 6 d, however, more than 92% of knocked-out larvae recovered within 24 h. The days of water immersion with 50% and 90% recovery ratios (indicated as RD50 and RD90) were 10.3 d and 6.4 d, respectively. When larvae were immersed less than 6 d, the mortality ratios of larvae were not significantly different from those that were not immersed at all. The days of immersion causing 50% and 90% mortality of larvae (MD50 and MD90, respectively) were 7.6 d and 11.1 d, respectively. The pupation ratios of larvae were also observed to be not significantly different compared to non-immersion, and the days of immersion causing 50% and 90% pupation (PD50 and PD90, respectively) were 6.6 d and 0.8 d, respectively. Larval respiration rates were reduced after water immersion as a strategy for larval survival. High water content was not detrimental to pupae of B. minax. Adult emergence did not significantly decrease in soil with high water content, even though pupae were under those conditions for 161-175 d. The respiration rates of pupae were lower in soil with different moisture levels and were not significantly different, which ensured the survival of pupae in high water content. Reduced respiration rate is a strategy for survival of larvae and pupae, and remarkable tolerance to high moisture conditions could explain the high rate of spread and geographical distribution of B. minax. The results of this study provide a reference for the occurrence and control of B. minax.