BACTROCERA INVADENS STEERING COMMITTEE, SOUTH AFRICA, September 2011
Bactrocera invadens, the African Invader fly, is a quarantine pest of Asian origin capable of infesting various commercial fruit crops. B. invadens was first detected on the African continent, in Kenya, in 2003. It is now listed in most countries in Western, Eastern and Central Africa as well as in some Southern African countries. In South Africa, a surveillance programme specifically targeting B. invadens is being carried out since 2006 by the National Plant Protection Organisation of South Africa (NPPOZA) in collaboration with fruit industries. Surveillance is carried out through trapping in some production areas, in major towns and at points of entry (border areas, border posts, ports and airports). In 2010, specimens of B. invadens were intercepted in two separate areas in northern Limpopo. The pest was successfully eradicated from both areas following timely intervention. Interceptions of the fly in South Africa are an indication that the areas currently free of this pest are under risk of incursions. As such, in March 2011, the National B. invadens Steering Committee called upon all producers of export fruit to commence monitoring for B. invadens and to maintain such monitoring as evidence that the farm remains free of this pest.
The trapping guidelines provided in this document aim at harmonizing all procedures for monitoring of B. invadens in production areas for early detection of the pest. Guidance is provided on how to conduct monitoring and keep records of all monitoring data.
Attractant and Traps
The attractant recommended for the survey is the para-pheromone methyl eugenol (ME). ME attracts males of Bactrocera invadens and other invasive Bactrocera species such as Bactrocera dorsalis and Bactrocera zonata.
Various ME dispensers are commercially available in South Africa. ME is available as slow release dispensers in form of either a plug or a fibre-board block (Invader Lure). ME should be used in bucket type traps such as Moroccan trap, Lynfield trap, Chempac Bucket trap and McPhail trap (Appendix 1). Only one ME dispenser must be placed per trap. Maximum precaution is required while handling ME in order to avoid contamination on the outside of the trap. When using ME with other fruit fly attractants (e.g. Questlure, Capilure, BioLure 3 component), preferably designate different persons to handle the different attractants in order to avoid cross contamination of traps.
An insecticide such as DDVP (Dichlorvos) must also be placed in the bucket type trap to kill any attracted flies. Dichlorvos is commercially available as solid strips and one small piece (1 cm x 1cm) should be used per trap.
Trap placement and trapping density
ME baited traps should be suspended on host trees such as mango, citrus, marula and guava in the orchard and/or in home-garden within the farm. A list of known hosts for B. invadens is provided in Appendix 2. The trap should be placed about 1.5 m above ground and should not be exposed to direct sunlight, strong wind and dust. Trap entrances should be cleared of leaves to allow access to flies and prevent entry of ants. The wire hanging the trap should be coated with a sticky ant barrier or Vaseline for further protection against ants. The minimum required trap density for surveillance is 1 trap per km2 or 1 trap per 100 ha, with at least 1 per Production Unit Code.
Once traps are placed, location of each trap should be recorded (Province, Area, Farm name, Production Unit Code (PUC), Host/cultivated crop, Orchard number, Block number, Trap number, Date trap set and GPS co-ordinates of the trap). This information must be recorded in a datasheet (See Appendix 3).
Traps should be serviced every week or fortnight. All trap services should be recorded on the datasheet (see Appendix 4). When servicing a trap, the trap must be opened and checked for any insect specimens caught. A B. invadens characteristic chart is currently available from Citrus Research International (Tel: 013 759 8000; Fax: 013 744 0578) and should be used as a reference when checking traps. If a suspect specimen is found, the specimen should be placed in a closed plastic vial. The vial containing the suspect specimen should be labeled as follows: Date of collection, PUC number, trap number and collector.This should be reported immediately to the relevant surveillance co-ordinator or to the Department of Agriculture, Forestry and Fisheries.
Contact points of the following co-ordinators are as follows:
Citrus – Aruna Manrakhan
firstname.lastname@example.org, 013 759 8000
Deciduous fruit including grapes – Leslie Brown
Leslie@fruitgro.co.za, 082 853 1471
Subtropical fruit – Wilna Stones
Wilna@subtrop.co.za, 015 307 3676
Small and new fruit crops - Elrita Venter
email@example.com, 082 346 2577
All other fruit and vegetable crops – Department of Agriculture, Forestry & Fisheries - Jan Hendrik Venter, JanHendrikV@nda.agric.za, 012 319 6384
The list of suppliers for trapping materials is provided in Appendix 5.
The ME dispenser and DDVP/Dichlorvos strip inside the trap should be replaced at least every 6 weeks. Old ME dispensers and DDVP strips must be disposed of properly away from the trapping site.
In the event that another insect is repeatedly caught in these traps, the relevant surveillance co-ordinator should be contacted to arrange for it to also be identified.
All information from trap servicing must be recorded: Date trap was checked, PUC number, trap number, replacement of attractant and insecticide, number of specimens caught. If there are no catches, this should also be recorded as “0” in the column of “number of specimens caught”.
Completed trapping records for each PUC must be supplied to DAFF at the end of each export season. DAFF will in future provide a procedure for annual submission of these records.
The existence of historic trapping data may be of great economic benefit to growers in that it will provide evidence of pest freedom in the event of the fly becoming established in South Africa. It is imperative that growers immediately make known (in accordance with the procedures described above) any catches of suspected B. invadens. Growers should not fear the consequences of quarantine in the event of such an early detection and the implementation of eradication procedures, since it is still possible to move (under permit) host material from such quarantined sites in compliance with established additional risk mitigation procedures. With early detection, the chances of successful eradication are very good.
Appendix 1. Trap description
The Morocco trap is a simple white bucket type of trap composed of a cylindrical plastic container with four equidistant holes on the upper third. A plastic basket is fitted in the lid in which the ME dispenser should be placed.
The Lynfield trap is a bucket type trap composed of a cylindrical plastic container with four equidistant holes on the upper third. The lid of the trap contains a hook to which an ME dispenser such as Invader Lure must be fitted.
The Chempac Bucket trap is a yellow cylindrical container with an opaque lid. A plastic basket can be fitted in the lid of the trap to contain an ME dispenser.
The McPhail trap consists of two parts, a clear lid and a yellow bottom section with an inverted funnel entrance underneath. The ME dispenser is suspended from a plastic basket at the top of the trap.