关键词: 扰动生境, 柱头可授性, 花粉活力, 泌蜜量, 访枣花昆虫

Abstract:

Objective: Jujube is a fruit-borne tree with entomophilous flowers. This study aims to explore the adaptability of flower-visiting insects to biological characteristics of jujube flowers by analyzing the differences of visiting behaviors of visiting insects in different disturbed habitats, which is beneficial to protect pollinating insects in jujube garden and lays a foundation for improving the pollination rate of jujube. Method: Huping jujube in Xiaobai Township, Taigu County, Shanxi Province was selected as the research object. The stigma receptivity, pollen viability and nectar secretion of jujube flowers were determined by benzidine-hydrogen peroxide method, iodide-iodine kalium staining method and micro sampler method, respectively. The number and behavior of flower-visiting insects in high disturbance and low disturbance jujube orchards were investigated by the method of visual observation, net catching and sticky plate. The collected data was subjected to statistical analysis. Result: 1) The flowering stage of jujube can be divided into seven stages: bud cracking stage, initial opening stage, sepal flattening stage, petal stamen separation stage, petal flattening stage, petal drooping stage and stamen drooping stage. The whole flowering process was completed within 24 hours. Anthers dehiscence occured at about 12:00 at noon on the flowering day. Pollen vitality reaches its maximum around 13:00, which is 68.35%. The stigma became mature at 16:30, and has the strongest receptivity from 13:00 to 15:00 on the second day after the blooming. The stigma receptivity and pollen viability of jujube flower presented the trend that first increased and then decreased. 2) A total of 3 090 visiting insects of jujube flowers were collected in the two plots, belonging to 8 orders, 57 families and 90 species, including Hymenoptera, Diptera, Coleoptera, Lepidoptera, Thysanoptera, Hemiptera, Neuroptera and Psocoptera. Among them, Hymenoptera, Diptera, Hemiptera and Coleoptera had the most families, accounting for 33.33%, 19.30%, 15.79% and 14.04% of the total families, respectively. Diptera, Thysanoptera and Hymenoptera had the largest number of individuals, accounting for 36.47%, 24.72% and 18.71% of the total number of individuals, respectively. 3) There were 703 flower-visiting insects of 43 species in high disturbance plots and 2 387 flower-visiting insects of 85 species in low disturbance plots. The flower-visiting insects of Hymenoptera had largest species in the two plots. The individual number of Thysanoptera insects was significantly higher than that of other orders, and the dominant flower-visiting insects were flower-eating insects in high disturbance plot. The individual number of Diptera was significantly higher than that of other orders in low disturbance plot. The dominant flower-visiting insects were pollinators, and the pollinators in low disturbance plots were significantly more than those in high disturbance plots. 4) The nectar secretion time of jujube flower was 12 hours. The nectar secretion amount was the most at about 13:00, and the number of flower-visiting insects was the largest at 10:00-16:00 in low disturbance plot. The peak period of flower-visiting insects and the period of more nectar secretion in the low disturbance plots were consistent with the time when the pollen vitality and stigma receptivity of jujube flowers were the strongest. The nectar secretion was the most at 19:00-22:00, and the number of flower-visiting insects was the most at 7:00-10:00 in the high disturbance plot. Insects visit flowers occurred mostly in the early morning which was inconsistent with the time when the pollen vitality and stigma receptivity of jujube flowers were the strongest. Conclusion: The species and quantity of flower-visiting insects in low disturbance plots are more than those in high disturbance plots. The dominant flower-visiting insects in the high disturbance plots are flower-feeding insects, while the dominant flower-visiting insects in the low disturbance plots are pollinators, and the number of species and individuals of pollinators are significantly larger than those in the high disturbance plots.The flower-visiting insects in high and low disturbance plots are adapted to nectar secretion characteristics of jujube flowers.

Key words: disturbance habitats, stigma receptivity, pollen vitality, nectar secretion, jujube flower-visiting insects