Gardner-Gee Robin, Dhami Manpreet K, Paulin Katherine J, Beggs Jacqueline R
School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
Environ Entomol. 2014 Dec;43(6):1514-25. doi: 10.1603/EN13292. Epub 2014 Nov 3.
Honeydew is abundant in many ecosystems and may provide an alternative food source (a buffer) for pollinators during periods of food shortage, but the impact of honeydew on pollination systems has received little attention to date. In New Zealand, kānuka trees (Myrtaceae: Kunzea ericoides (A. Rich) Joy Thompson) are often heavily infested by the endemic honeydew-producing scale insect Coelostomidia wairoensis (Maskell) (Hemiptera: Coelostomidiidae) and the period of high honeydew production can overlap with kānuka flowering. In this study, we quantified the sugar resources (honeydew and nectar) available on kānuka and recorded nocturnal insect activity on infested and uninfested kānuka during the flowering period. Insects were abundant on infested trees, but flowers on infested trees received fewer insect visitors than flowers on uninfested trees. There was little evidence that insects had switched directly from nectar-feeding to honeydew-feeding, but it is possible that some omnivores (e.g., cockroaches) were distracted by the other honeydew-associated resources on infested branches (e.g., sooty molds, prey). Additional sampling was carried out after kānuka flowering had finished to determine honeydew usage in the absence of adjacent nectar resources. Moths, which had fed almost exclusively on nectar earlier, were recorded feeding extensively on honeydew after flowering had ceased; hence, honeydew may provide an additional food source for potential pollinators. Our results show that honeydew resources can impact floral visitation patterns and suggest that future pollinator studies should consider the full range of sugar resources present in the study environment.
甘露在许多生态系统中都很丰富，在食物短缺时期可能为传粉者提供替代食物来源（一种缓冲），但甘露对授粉系统的影响迄今为止很少受到关注。在新西兰，卡努卡树（桃金娘科：昆士亚树（A. Rich）乔伊·汤普森）经常受到当地产甘露的介壳虫怀罗伊介壳虫（马斯克尔）（半翅目：介壳虫科）的严重侵害，甘露高产期可能与卡努卡树开花期重叠。在本研究中，我们量化了卡努卡树上可获得的糖分资源（甘露和花蜜），并记录了开花期受侵害和未受侵害的卡努卡树上夜间昆虫的活动情况。受侵害的树上昆虫数量很多，但受侵害树上的花朵比未受侵害树上的花朵吸引到的昆虫访客更少。几乎没有证据表明昆虫直接从采食花蜜转而采食甘露，但有可能一些杂食性动物（如蟑螂）被受侵害树枝上与甘露相关的其他资源（如烟煤霉菌、猎物）分散了注意力。在卡努卡树花期结束后进行了额外采样，以确定在没有相邻花蜜资源的情况下甘露的利用情况。之前几乎只采食花蜜的蛾子，在花期结束后被记录到大量采食甘露；因此，甘露可能为潜在传粉者提供额外的食物来源。我们的研究结果表明，甘露资源会影响访花模式，并建议未来的传粉者研究应考虑研究环境中存在的所有糖分资源。
