CORE Metadata, citation and similar papers at core.ac.uk Provided by South East Academic Libraries System (SEALS) Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a Potential Biological Control Agent for the Submerged Aquatic Weed, Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae) Authors: G.D. Martin, J.A. Coetzee, and J-R. Baars Source: African Entomology, 21(1) : 151-160 Published By: Entomological Society of Southern Africa URL: https://doi.org/10.4001/003.021.0118 BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Complete website, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/terms-of-use. Usage of BioOne Complete content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Downloaded From: https://bioone.org/journals/African-Entomology on 18 Feb 2019 Terms of Use: https://bioone.org/terms-of-use Access provided by Rhodes University Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), a potential biological control agent for the submerged aquatic weed, Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae) G.D. Martin1*, J.A. Coetzee1 & J-R. Baars2 1Department of Zoology and Entomology, Rhodes University, P.O. Box 94, Grahamstown, 6140 South Africa 2BioControl Research Unit, School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland The leaf-mining fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae), was investigated in its native range in South Africa, to determine its potential as a biological control agent for Lagarosiphon major (Ridl.) Moss ex Wager (Hydrocharitaceae), an invasive submerged macrophyte that is weedy in many parts of the world. The fly was found throughout the indigenous range of the plant in South Africa. High larval abundance was recorded at field sites with nearly all L. major shoots sampled ontaining larvae, with densities of up to 10 larvae per shoot. Adults laid batches of up to 15 eggs, usually on the abaxial sides of L. major leaves. The larvae mined internally, leaving the epidermal tissues of the upper and lower leaves intact. The larvae underwent three instars which took an average of 24 days and pupated within the leaf tissue, from which the adults emerged. Impact studies in the laboratory showed that H. lagarosiphon larval feeding significantly restricted the formation of L. major side branches. Based on its biology and damage caused to the plant, Hydrellia lagarosiphon could be considered as a useful biological control candidate for L. major in countries where the plant is invasive. Key words: submersed aquatic macrophyte, native range survey, natural enemy, leaf damage, weed biological control. INTRODUCTION Lagarosiphon major (Ridl.) Moss ex Wager 1995) and the small blunt unicellular spines with (Hydrocharitaceae) is a submerged aquatic 2–3 rows of fibres on their margin, only seen under macrophyte indigenous to southern Africa (Cook a microscope (Symoens & Triest 1983). The roots 2004), but has been introduced to Australia, New vary in length but may grow up to 50 cm and are Zealand, the United Kingdom (including Ireland), capable of penetrating deep into the substrate. and mainland Europe (Howard-Williams & Davies Single stems arise from the roots and branch 1988; Bowmer et al. 1995; Baars et al. 2010; ISSG repeatedly as they rise through the water column, 2011), probably through the aquarium and horti- producing an extremely dense surface canopy cultural trade. It has become invasive in many (Caffrey et al. 2010). The stems are more robust waterways in these countries, and is particularly than other Lagarosiphon spp. (Cook 2004), but they difficult to control using traditional methods of nevertheless break easily under the influence of mechanical removal and chemical application wind or wave action, which aids in the natural (Caffrey et al. 2011). Biological control using insect spread of the plant as these stem fragments can natural enemies of L. major could be a suitable root (Caffrey & Acevedo 2007). Under favourable alternative to complement other control methods. conditions, dense growth of the plant can block Lagarosiphon major can grow to a depth of7min light penetration into waterways, eliminating clear water; it thrives in shallow, muddy, alkaline growth of native water plants and negatively waters but is capable of establishing under most affecting aquatic fauna (Rattray et al.1994). Large aquatic conditions (Caffrey & Acevedo 2007). It mats may choke shallow dams and rivers (Cook can be distinguished from other similar looking 2004), thereby restricting the passage of boats, species of Hydrocharitaceae by its recurved leaves limiting recreational activities such as swimming arranged spirally around the stem (Bowmer et al. and angling, and blocking intakes to hydro-electric *Author for correspondence. generators (Bowmer et al. 1995; James et al. 1999; E-mail: [email protected] McGregor & Gourlay 2002). African Entomology 21(1): 151–160 (2013) Downloaded From: https://bioone.org/journals/African-Entomology on 18 Feb 2019 Terms of Use: https://bioone.org/terms-of-use Access provided by Rhodes University 152 African Entomology Vol. 21, No.1, 2013 Weedbiological control programmes have focused MATERIAL AND METHODS largely on terrestrial and free-floating aquatic plant invaders with comparatively little attention Field surveys given to the majority of submerged invasive Botanical records from the South African National macrophytes, including L. major (Bennett & Biodiversity Institute (SANBI) and Rhodes Univer- Buckingham 2000; Schutz 2007; Baars et al. 2010). sity were used to determine the distribution of However, other Hydrocharitaceae species have L. major in South Africa (Baars et al. 2010). Surveys been targeted with biological control. The closely for potential biological control agents across the related hydrilla, Hydrilla verticillata (L.f.) Royle distribution of L. major were undertaken in Novem- (Hydrocharitaceae), an invasive species in the ber 2008 (Baars et al.2010), December 2009 and May United States, has been surveyed extensively in 2010. Sites in the Eastern Cape Province were Asia and Australia and more than 25 species of regularly surveyed between 2008 and 2011. herbivorous insects, from five orders, have been The holotype (specimen number TYPH01958) of identified. Of these, four have been released in the H. lagarosiphon, housed at the National Collection United States as biological control agents (Bennett of Insects, Biosystematics Division, Agricultural & Buckingham 2000) and include two weevils, Research Council-Plant Protection Research Insti- Bagous hydrillae O’Brien and B. affinis Hustache tute, South Africa,was collected from Featherstone (Coleoptera: Curculionidae) (Buckingham & Farm Dam, near Stutterheim in the Eastern Cape Bennett 1998; Balciunas et al. 1996), and two flies, (32.57746S 27.49583E). Before being submitted Hydrellia balciunasi Bock and Hydrellia pakistanae to the National Museum of Wales, Cardiff, for Deonier (Diptera: Ephydridae). Hydrellia paki- description, a culture of the fly collected from stanae has been successful in the long-term Featherstone Farm was established at University management of H.verticillata in controlled experi- College Dublin, Ireland. To ensure that the same mentation and at field sites (Doyle et al. 2002; species of Hydrellia was feeding on L. major through- Grodowitz et al. 2003), and is being considered for out South Africa, Hydrellia spp. were collected from the water surface above mats at release in South Africa (Coetzee et al. 2011) where L. major selected sites in South Africa, reared to F3 genera- H. verticillata was discovered in 2006 (Henderson tion on L. major, and then sent for comparison with 2006). An unidentified species of Hydrellia (Dip- the holotype specimen (Deeming 2012). tera: Ephydridae), recently identified from Brazil, Where H. lagarosiphon was found in the field, has shown promise as a candidate agent for Brazil- 100 L. major shoots, approximately 15–20 cm long, ian water weed, Egeria densa Planch (Hydro- were examined for the presence of larvae and charitaceae), another submerged species that is puparia of H. lagarosiphon. All infested material becoming problematic in several countries world- was returned to the laboratory and placed in wide (Cabrera Walsh et al. 2012). Lagarosiphon major emergence chambers. Any adults emerging from may thus also be a suitable target for biological the material were identified. Distribution records control. of H. lagarosiphon arising from the field surveys were As yet, no biological control programmes have overlaid onto a map incorporating mean daily been implemented against L. major anywhere in minimum temperature data during the coldest the world. Thus, field surveys in the plant’s native months in South Africa (Schulze 1997), using range in South Africa were undertaken to identify ArcView