Invasive Hakeas — Biological Control Implementations
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Invasive Hakeas — Biological Control Implementations A. Fourie, A. J. Gordon1 and R. M. Krug2 17th October 2012 DRAFT 1Plant Protection Research Institute, Private Bag X5017, Stellenbosch, 7599 SOUTH AFICA [email protected] 2Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland 7602 SOUTH AFRICA [email protected] DRAFT 1 rev 210, 14:28:27, 2012-10-17 Contents 1 The Hakea species4 1.1 Biology................................4 1.1.1 Hakea sericea .........................4 1.1.2 Hakea gibbosa .........................4 1.1.3 Hakea drupacea ........................5 1.1.4 Biology of Hakea salicifolia (willow hakea)........5 1.2 Ecology and spread.........................7 1.3 Control measures...........................8 1.3.1 Mechanical control......................8 1.3.2 Chemical control.......................8 1.3.3 Biological control.......................8 2 Agents 11 2.1 Gummosis fungus........................... 11 2.1.1 Description.......................... 11 2.1.2 Disease Symptoms...................... 11 2.1.3 Impact on Hakea sericea ................... 11 2.2 Seed weevil.............................. 12 2.2.1 Description.......................... 12 2.2.2 Life Cycle........................... 12 2.2.3 Feeding Damage....................... 14 2.3 Seed moth............................... 14 2.3.1 Description.......................... 14 2.3.2 Life cycle........................... 15 2.3.3 Feeding damage....................... 15 2.4 Stem-boring beetle.......................... 15 2.4.1 Description.......................... 15 2.4.2 Life cycle........................... 15 2.4.3 Feeding damage....................... 17 2.5 Bud-weevilDRAFT.............................. 17 2.5.1 Description.......................... 17 2.5.2 Life cycle........................... 17 2.5.3 Feeding damage....................... 18 2.6 Leaf weevil.............................. 18 2.6.1 Description.......................... 18 2.6.2 Life cycle........................... 19 2.6.3 Feeding damage....................... 19 2 CONTENTS CONTENTS 3 Guidelines 20 3.1 Information needed and initial considerations........... 20 3.2 Biological control strategy...................... 21 3.3 Release Site.............................. 22 3.4 Biological Control Agent....................... 24 3.5 Specific guidelines.......................... 24 3.5.1 Gummosis fungus Colletotrichum acutatum........ 25 3.5.1.1 Implementation procedure............ 25 3.5.1.1.1 Mature hakea trees........... 25 3.5.1.1.2 Hakea seedlings............. 26 3.5.1.2 Indication of presence............... 28 3.5.2 Seed weevil Erytenna consputa Collection procedure... 29 3.5.2.1 Collection procedure................ 29 3.5.2.2 Implementation procedure............ 29 3.5.2.3 Indication of presence............... 29 3.5.3 Seed moth Carposina autologa ............... 30 3.5.3.1 Collection procedure................ 30 3.5.3.2 Implementation procedure............ 30 3.5.3.3 Indication of presence............... 30 3.5.4 Stem-boring beetle Aphanasium australe .......... 31 3.5.4.1 Collection procedure................ 31 3.5.4.2 Implementation procedure............ 31 3.5.4.3 Indication of presence............... 32 3.5.5 Bud-weevil Dicomada rufa ................. 34 3.5.5.1 Collection procedure................ 34 3.5.5.2 Implementation procedure............ 34 3.5.5.3 Indication of presence............... 34 3.5.6 Leaf weevil Cydmaea binotata ................ 35 3.5.6.1 Collection procedure................ 35 3.5.6.2 Implementation procedure............ 35 3.5.6.3 Indication of presence............... 35 4 Monitoring after release 36 5 Additional information 37 5.1 Literature............................... 37 5.2 Acknowledgements.......................... 38 5.3 Contact information......................... 38 5.4 AddressesDRAFT............................... 39 3 rev 210, 14:28:27, 2012-10-17 Chapter 1 The Hakea species Four species of hakea were introduced to South Africa from Australia between 1835 and 1858. Three species (Hakea sericea, H. gibbosa and H. drupacea) have become environmental weeds while the fourth species (H. salicifolia) has only recently been observed invading fynbos areas. Hakea sericea is the most serious and widespread of the hakeas and factors thought to have contributed to its suc- cess as an invader in South Africa are its copious production of serotinous seeds (after the death of the plant the fruits split open within a couple of days and drop their seeds), the high seed longevity in the canopy, efficient seed dispersal and absence of seed predators. 1.1 Biology 1.1.1 Hakea sericea The weed Hakea sericea, native to south-eastern Australia, is one of the most serious alien invasive trees in nearly all the coastal mountains of the Western and Eastern Cape Provinces. It is classified as a category 1 weed in South Africa and is therefore prohibited on any land or water surface and must be controlled or eradicated where possible. H. sericea is commonly known as silky hakea and is typically an erect single-stemmed, much-branched shrub or tree up to 5 m high. It has dark-green needle-like leaves 1mm in diameter and up to 40 mm long with sharply pointed tips. The mature fruit of H. sericea is a heat-resistant woody follicle (20–25 mm in diameter) which contains two winged seeds. The seeds produced annually are stored in the canopy and are only released after the death of the plant, usually by fire. There is no seed bank in the soil. 1.1.2 HakeaDRAFT gibbosa Hakea gibbosa is endemic to New South Wales and southern Queensland, Aus- tralia and is not as widespread as H. sericea in South Africa. It occurs on the Cape Peninsula, the Kleinrivierberg and the adjoining mountains near Her- manus and Stanford. It is also classified as a category 1 weed in South Africa. Hakea gibbosa is commonly known as rock hakea and is typically an erect branched shrub or tree up to a height of 3 m. It has stiff, hairy, grey-green needle-like leaves 1 mm in diameter and up to 80 mm long with sharply pointed 4 1.1. BIOLOGY CHAPTER 1. THE HAKEA SPECIES Figure 1.1: Hakea sericea flowers and plant tips. The mature fruit of H. gibbosa is a heat-resistant woody follicle (35 mm long and 30 mm in diameter) which contains two winged seeds. The seeds pro- duced annually are stored in the canopy and are only released after the death of the plant. 1.1.3 Hakea drupacea Hakea drupacea is endemic to coastal regions of south-western Australia and some islands in the adjacent Recherché Archipelago. In South Africa it is re- stricted to the Cape Peninsula, Somerset West, Franschhoek, Bot River, Haw- ston and the Kleinrivier mountains. It occurs on the Cape Peninsula, the Kleindrakenstein berg, the Kleinrivierberg and the adjoining mountains near Hermanus and Stanford. It is also classified as a category 1 weed in South Africa. Hakea drupacea is commonly known as sweet hakea and is much branched, roun- ded shrub or tree up to a height of 6 m. The adult leaves are dark green, hairless, up to 100 mm long with sharply pointed tips. The leaves are usually divided into upright, 30–50 mm long sharp-pointed needles. The mature fruit of H. drupacea is a heat-resistant woody follicle (25 mm long and 20 mm in diameter) which contains two winged seeds. The seeds produced annually are stored in the can- opy and are only released after the death of the plant. Hakea drupacea produces far fewer viable seed than H. sericea and H. gibbosa and is not as invasive as H. sericea.DRAFT No biological control agents have been introduced for this weed. 1.1.4 Biology of Hakea salicifolia (willow hakea) Hakea salicifolia is endemic to the eastern part of New South Wales and the extreme south east of Queensland, Australia and occurs in open forests. It is not widespread in South Africa and small infestations occur in Du Toits Kloof near Paarl, Kleinmond, Bot River, George and Knysna in the Western Cape. Localised infestations also occur in Stutterheim and Hogs back in the Eastern 5 rev 210, 14:28:27, 2012-10-17 1.1. BIOLOGY CHAPTER 1. THE HAKEA SPECIES DRAFTFigure 1.2: Hakea gibbosa flowers 6 rev 210, 14:28:27, 2012-10-17 1.2. ECOLOGY AND SPREAD CHAPTER 1. THE HAKEA SPECIES Figure 1.3: Hakea drupacea plant and seeds Missing figure Hakea salicifolia picture Figure 1.4: Hakea salicifolia Cape. It is not a declared invader at present. Hakea salicifolia is a fast-growing shrub or small tree which grows up to 5 m tall. The leaves are narrow and grow up to 10 cm long. The flowers are white, small and occur in the leaf axils. The woody fruits are much smaller than those of H. sericea and H. gibbosa and are approximately 20 mm long and 15 mm wide and contain two winged seeds. The fruits remain on the plants and the seed are only shed after the death of the plant, usuallyDRAFT as a result of fire. No biological control agents have been introduced for this plant. 1.2 Ecology and spread In South Africa H. sericea occurs in Mediterranean-type climates that have a summer drought, a summer rainfall region and an area with rainfall throughout the year. Hakea gibbosa and H. drupacea occur in the winter rainfall region. 7 rev 210, 14:28:27, 2012-10-17 1.3. CONTROL MEASURES CHAPTER 1. THE HAKEA SPECIES Widespread fires in the Western and Eastern Cape mountains have resulted in massive regeneration of H. sericea. Dense stands of hakea can alter the composition of plant and animal communities, increase fire intensities, increase evapotranspiration from important water catchment areas and restrict access to mountain areas. The rate of spread of H. sericea has been impressive in the south-western region of the Western Cape Province, with 9 000 ha, 111 345 ha, 279 200 ha and 360 000 ha invaded in 1939, 1969, 1974 and 1983 respectively. 1.3 Current control measures 1.3.1 Mechanical control Present control measures include mechanical clearing, chemical and biological control. The most successful mechanical control method is the fell and burn technique.