Ppnews No 79

Plant Protection Research Institute January –March 2009 No 79 PLANT PROTECTION NEWS Newsletter of the Plant Protection Research Institute (PPRI), an institute in the Natural Inside this issue: Resources and Engineering Division of the Agricultural Research Council (ARC) Biocontrol of 1-2 Invasive cactus Biocontrol of invasive cactus exceeds all expectations Bee Disease 2 A highly exciting discovery was recently made 3-6 during the first post-release monitoring of a bio- Biosystematics control agent released against a problematic cactus weed near Musina in Limpopo province. Insect Ecology 7 Plant Protection News No. 78 reported on the first releases of a biotype of the cochineal spe- Pesticide Science 8 cies, Dactylopius tomentosus, against this cactus, chain-fruit cholla (Cylindropuntia fulgida var. fulgida) during November 2008. Plant Pathology 9 Weeds Research 10-12 Technology transfer 13-14 Cochineal-infested cactus plant starting to droop Every areole infested with cochineal Editorial Committee On 18 March 2009 (exactly 4 months after re- Ansie Dippenaar-Schoeman lease), Hildegard Klein (ARC-PPRI), Dr Helmuth (ed.) Hildegard Klein Zimmermann (the country’s most well-known Almie van den Berg cactus biocontroller, previously of ARC-PPRI) Cladodes having been killed by cochineal, drop- Ian Millar together with five employees of the Working for ping off a large cactus plant Marika van der Merwe Water Programme, visited the release site again, Tanya Saayman hoping to find some early signs that the cochineal Petro Marais insects had become established. To their utter Elsa van Niekerk amazement, the cochineal had not only become Roger Price established on each of the inoculated plants, but General inquiries the inoculated plants were virtually covered from top to bottom with clusters of D. tomentosus Plant Protection Research females. What is more, they had already started Institute dispersing, with most of the C. fulgida plants Private Bag X134 within a radius of 3 m or more from the inoculated Queenswood plants infested. Many small plants consisting of 0121 only a few cladodes had already died and young South Africa plants less than 1 m tall were collapsing. The side branches of large plants were beginning to e-mail: [email protected] droop, many of the lower cladodes had dropped A dead Woodlands Kingfisher impaled on the off the plants, and many of these were dead. cactus spines website: http://www.arc.agric.za The rate of population build-up and dispersal of This exceptional performance by this cochineal the cochineal biotype, as well as its damage to Information may be used biotype was predicted by Catherine Mathenge, the cactus, have exceeded all expectations. In currently living in Australia, but previously based freely with acknowledge- the four months since its release in Musina it has ment to the source. at PPRI’s Rietondale campus, where she carried achieved a level of success that is normally ex- out research into the performance of different pected only after a year or more. It is expected to biotypes of Dactylopius tomentosus on various become one of South Africa’s most spectacularly closely related cactus species. successful biocontrol projects. PLANT PROTECTION NEWS No 79 Page 2 These measures are enforced by the necessary regulations, backed Biocontrol of invasive cactus up by extensive inspection and analytical services. If the disease is (cont.) not contained and eradicated, it will almost certainly spread throughout South Africa, and eventually to neighbouring countries and throughout sub-Saharan Africa. The impact will be severe in the Catherine’s results indicated that the biotype of the cochi- short-term, with organized beekeeping having to adapt very swiftly neal collected from Cylindropuntia cholla (which is believed to the disease and the new management procedures that it re- to be synonymous with Cylindropuntia fulgida var. mamil- quires. lata) in Mexico, was more damaging to the weedy C. fulgida var. fulgida in South Africa than another biotype of the The steps that the National Department of Agriculture (DoA) will same cochineal species that had been collected from C. take are as follows: fulgida var. fulgida in Arizona, USA. A. To conduct an urgent yet extensive delimiting survey of the This might be ascribed to the fact that this is a “new asso- Western Cape to determine how widespread and extensive the ciation” between an insect and a plant species that did not AFB infection is, and particularly, whether it is present in the co-evolve. Had it not been for Ms Mathenge’s recommen- wild honeybee population. This survey will be conducted by dation, this particular cochineal biotype would probably not ARC-PPRI, assisted by DoA inspectors from the Directorate have been imported, and biocontrol of this cactus weed in Agricultural Product Inspection Services (APIS). In addition, South Africa might have remained mediocre. beekeepers may be requested to assist with the survey. On a different note: the devastation that this invasive cactus B. Once the extent and distribution of the AFB presence is known, can cause to biodiversity was brought home to the monitor- the DoA, in consultation with organized beekeeping and other ing team by the pitiful sight of three dead Woodlands King- stakeholders, will decide on the appropriate course of action to fishers that had become impaled on the cactus spines on be followed. This is likely to entail an attempt to quarantine and the small island in the dry bed of the Limpopo River where eradicate the disease. the biocontrol agents had been released. Cactus collectors are urged to keep the invasive potential of cacti in mind and In the interim, beekeepers are strongly urged to adopt extreme pre- to prevent escapes from their gardens. cautionary measures to prevent the disease spreading further, and to prevent their apiaries from contracting the disease. This applies Contact: Hildegard Klein at [email protected] to all beekeepers in South Africa, but particularly those in the West- ern Cape. The suggested measures are as follows: • Beekeepers should endeavour to keep all apiaries isolated Bee Disease Threatens South Afri- from each other; that is, do not move honeybee colonies from can Apiculture apiary to apiary. • Beekeepers should not place their colonies in the near prox- imity of colonies belonging to other beekeepers. American foulbrood (AFB) is an extremely serious bacterial • Do not move equipment (brood boxes, supers, frames) from disease of honeybee brood, caused by the bacterium Pae- apiary to apiary, or from colony to colony. nibacillus larvae. It results in the death of honeybee larvae and, in serious cases, the collapse and death of the honey- • Sterilize all beekeeping equipment (hive tools, gloves) with bee colony. AFB is found almost world-wide, but has previ- alcohol or boiling water after use, so as not to spread the infec- ously not been reported in sub-Saharan Africa. AFB was tion from apiary to apiary or from colony to colony. recently found in South Africa for the first time during an Do not put out wet supers for bees to feed from. ARC survey for AFB, funded by the Department of Agricul- • ture. The origin of the AFB in South Africa is unknown, but • Do not feed colonies with anything containing honey or pollen. is likely to be as a result of non-irradiated honey being brought into the country. Other possible avenues for entry • Keep robbing to an absolute minimum, and hence, keep bee- are imported beeswax, imported bee-food, or ship-borne keeping management to a minimum. honeybee swarms. For many years, South Africa has in- sisted on the compulsory irradiation of all bee products Contact: Mike Allsopp at [email protected] entering the country, specifically to prevent the entry of AFB. Since the first report in February 2009, a preliminary survey for AFB in bee colonies in the Western Cape was under- taken by the ARC-PPRI's Mike Allsopp who is the only agricultural honeybee researcher in South Africa and the only bee disease specialist. Laboratory analyses were un- dertaken by Dr Teresa Goszczynska, ARC-PPRI's bacteri- ologist at Roodeplaat. AFB is a notifiable disease in almost all countries, including South Africa. Clinical symptoms in colonies are diseased larvae and pupae, which collapse into a mucus-like mass at the base of a cell, and then dry into a hard, black scale. The colony has a sickly, 'old boots' smell. In almost all parts of the world there are regulations controlling the spread of AFB in honeybee colonies. These controls mostly require the immediate destruction (normally by burning) of infected colonies, and prohibitions of movement of other nearby colonies for 18-24 months, until colonies are shown to be infection free. Symptoms of AFB are diseased larvae and pupae, which collapse into a mucus-like mass at the base of a cell, and then dry into a hard, black scale PLANT PROTECTION NEWS No 79 Page 3 Biosystematics Productive collaboration on southern African Tortoise Beetles The enthusiasm of independent researchers is often ‘contagious’ and very encouraging! This was the case when Hugh Heron, a retired school teacher and independent researcher from Escombe, Durban, spent a few days in January working on the tortoise beetle (Chrysomelidae: Cassidinae) collection with Beth Grobbelaar, beetle taxonomist at ARC-PPRI’s South African Na- tional Collection of Insects (SANC). Working about 11-hour days, beavering away over drawers full of specimens, he managed to work his way through the entire collection, identifying many species previously unnamed in the collection. The result is a vastly improved identified collection at the SANC, only one drawer containing a few specimens as yet unnamed, a diary of notes that took about two weeks to decipher Aspidimorpha puncticosta, one of the largest South African upon his return to Durban, and the cherry on top - a summary that cassidines (13x11.2 mm).

Load more