ABSTRACT

Dactylopius opuntiae ‘stricta’ lineage was released more than 20 years ago in South Africa where it has successfully controlled Opuntia stricta. However, its host preference had not been tested against all invasive cacti in South Africa. Therefore, the possibility exists that it might successfully control other invasive cacti. We compared the performance of the ‘stricta’ lineage on Opuntia stricta, Opuntia humifusa and two lineages of Opuntia engelmannii. Additionally, we assessed if morphology of these Opuntia taxa could be used as an indicator of host selection by the ‘stricta’ lineage of D. opuntiae. Acceptability and suitability of the host taxa were measured by D. opuntiae life history parameters such as crawler development time and female weight. Principal component analysis of six morphometric characters of the Opuntia taxa was used to assess similarities between the taxa. Opuntia stricta is morphologically more similar to the O. engelmannii lineages than to O. humifusa, which showed little similarity to any of the other taxa. Additionally, the two O. engelmannii lineages showed some morphological similarity to each other. The ‘stricta’ lineage completed its development on O. humifusa such that the cochineal could be considered as a potential biological control agent for O. humifusa. Conversely, D. opuntiae ‘stricta’ was not able to complete development on O. engelmannii. Consequently, it would not be a suitable biological control agent for either lineage of O. engelmannii. The results show that O. humifusa is a suitable host for D. opuntiae ‘stricta’ and that Opuntia morphology is not an obvious indicator of host suitability.

摘要

Dactylopius opuntiae 'stricta' 谱系于 20 多年前在南非被释放，在那里它成功控制了仙人掌。然而，其宿主偏好尚未针对南非的所有入侵仙人掌进行测试。因此，它有可能成功控制其他侵入性仙人掌。我们比较了 'stricta' 谱系在Opuntia stricta、Opuntia humifusa和Opuntia engelmannii 的两个谱系上的表现。此外，我们评估了这些仙人掌分类群的形态是否可以用作仙人掌的“严格”谱系选择宿主的指标。宿主分类群的可接受性和适用性通过以下方式衡量D.仙人掌生活史参数，如履带发育时间和雌性体重。仙人掌类群的六个形态特征的主成分分析用于评估类群之间的相似性。与O. humifusa相比，Opuntia stricta在形态上更类似于O. engelmannii谱系，而O. humifusa与任何其他分类群几乎没有相似性。此外，两个O. engelmannii谱系显示出彼此的一些形态相似性。'stricta' 谱系在O. humifusa上完成了开发，因此胭脂虫可以被视为O的潜在生物防治剂。腐殖质. 相反，D. opuntiae 'stricta' 不能在O. engelmannii上完成发育。因此，它对于O. engelmannii 的任一谱系都不是合适的生物防治剂。结果表明，O. humifusa是D. opuntiae 'stricta'的适宜寄主，而仙人掌形态不是寄主适宜性的明显指标。