Cryptic species of a water hyacinth biological control agent revealed in South Africa: host specificity, impact, and thermal tolerance. Issue 7 (19th July 2019)

• Record Type: Journal Article
• Authors: Paterson, Iain D.; Coetzee, Julie A.; Weyl, Philip; Griffith, Tamzin C.; Voogt, Nina; Hill, Martin P.
• Is Part Of: Entomologia experimentalis et applicata. Volume 167:Issue 7(2019)
• Page Start: 682
• Page End: 691
• Publication Date: 2019-07-19
• Subjects: Eccritotarsus eichhorniae -- Eccritotarsus catarinensis -- Eichhornia crassipes -- host range testing -- thermal physiology -- weed biocontrol -- agent efficacy -- Pontederiaceae -- Heteroptera -- Miridae; Entomology -- Periodicals; 595.7
• DOI: 10.1111/eea.12812
• Languages: English
• ISSNs: 0013-8703

Abstract

Abstract: The discovery that cryptic species are more abundant than previously thought has implications for weed biological control, as there is a risk that cryptic species may be inadvertently released with consequences for the safety of the practice. A cryptic species of a biological control agent released for the control of the invasive alien macrophyte, water hyacinth, Eichhornia crassipes (C. Mart.) Solms. (Pontederiaceae), was recently discovered in South Africa. The two species were considered a single species prior to genetic analysis and interbreeding experiments. The original biological control agent retains the name Eccritotarsus catarinensis (Carvalho) (Heteroptera: Miridae) whereas the new species has been described as Eccritotarsus eichhorniae Henry. In this study, we compared the host specificity, efficacy, and thermal physiologies of the two species. The host specificity of the two species within the Pontederiaceae was very similar and both are safe for release in South Africa. Comparison of the per capita impact of the two species indicated that E. eichhorniae was the more damaging species but this is likely to be influenced by temperature, with E. catarinensis being more effective under lower temperatures and E. eichhorniae being more effective under higher temperatures. Releasing the correct species for the thermal environment of each release site will improve the level of control of water hyacinth in South Africa. This example highlights the need to keep populations of biological control agents from different native range collection localities separate, and to screen for host specificity and efficacy. Abstract : A cryptic species, Eccritotarsus eichhorniae (Heteroptera: Miridae), was discovered within a population of Eccritotarsus catarinensis, a biological control agent of water hyacinth, Eichhornia crassipes (Pontederiaceae). The recently described cryptic species is more effective than the original agent but this is likely to be mediated by climatic conditions: the impact of E. catarinensis is greater under lower temperatures and E. eichhorniae has a greater impact under higher temperatures.