关键词: 橘小实蝇, 苹果, 生长发育, 选择偏好, 选择适应性

Abstract:

【Objective】 This study aims to investigate the preference of Bactrocera dorsalis for fruits of six main Malus pumila varieties and to understand the effects of different varieties of M. pumila on the growth and development of B. dorsalis. 【Method】 Three early maturing varieties (Huashuo, Honglu, Gala) and three late maturing varieties (Duanzhifushi, Yanfu No. 3, Qincui) were used as test materials. The hardness and sugar content of M. pumila fruit were determined by hardness tester and a brix refractometer. Three types of fruit handling methods were employed: whole fruit, peeled fruit and fruit odor. Fruits of the same ripening batch of the same handling method were placed in rearing cages, to measure the numbers of visits and laid eggs by B. dorsalis on fruits of different varieties were determined. Feeding different varieties of fruits to the first hatching larvae, the growth and development parameters of larval duration, pupation rate, pupal weight and other parameters after feeding were determined. The selection preference and development adaptability of B. dorsalis to different varieties of M. pumila were analyzed. 【Result】 There were differences in the numbers of visits and laid eggs of B. dorsalis on different varieties of fruits. The female adults were more sensitive to different varieties and fruit handling methods. B. dorsalis preferred to choose Gala among whole fruits of the early maturing varieties, which had 9.0 female visits and 105.0 eggs per fruit, respectively. While among the late maturing varieties, B. dorsalis showed a stronger preference for Qincui, and the numbers of female visits and laid eggs on this variety reached to 5.5 and 64.2 eggs per fruit, respectively. The fruit handling methods influenced the selection preference of B. dorsalis. With the exception of Gala, the numbers of visits and laid eggs on peeled fruits were higher in different fruit handling methods of the same variety. Among the early maturing varieties, Huashuo had held the highest number of laid eggs on the peeled fruit, reached to 201.6 eggs per fruit, and among the late maturing varieties, Yanfu No. 3 had held the highest number of laid eggs on fruit odor, reached to 83.8 eggs per device. Two-way ANOVA found that variety and fruit handling method had an impact on the number of visits and laying eggs. Larvae of B. dorsalis had held the shortest period of 11.9 d in Gala and the shortest pupal stage in Huashuo of 9.9 d after feeding on different fruits. Pupation and emergence rates were higher in late maturing varieties. The difference in the age-stage-specific survival rate of the larvae that fed on different varieties was mainly in the 2nd instar stage, and the 2nd instar larvae which fed on Huashuo and Gala had held fastest development rate and peaked at the 3rd day. 【Conclusion】 There were differences in the selection preference of B. dorsalis on different M. pumila varieties. Gala was preferred in early maturing varieties, while Qincui was preferred in late maturing varieties. Fruit integrity and fruit odor had an effect on the selection preference. The numbers of visits and laid eggs on peeled fruit and fruit odor were generally higher than those on whole fruit. B. dorsalis can finish the growth and development of larvae on M. pumila fruit, and it has the ability to reproduce damage in apple orchards. The correlation between the preference of B. dorsalis for M. pumila fruit and the fitness of offspring’s growth and development is not strong, which is different from the hypothesis of “selectivity and fitness”. In the comprehensive management of B. dorsalis in apple orchards, the damage monitoring of Gala and Qincui varieties should be strengthened, and the damaged fruits should be avoided and removed in time in agricultural operations.

Key words: Bactrocera dorsalis, apple (Malus pumila), growth and development, selection preference, selective adaptability