Presentation on theme: "Taxonomy, biology and management"— Presentation transcript:
1Taxonomy, biology and management Fruit fliesTaxonomy, biology and management(and some key references and names)Paul Ferrar
2Fruit fly taxonomy Order Diptera (flies) Family Tephritidae Subfamily DacinaeGenus BactroceraContains most of the important pest species of Asia and the South PacificGenus Dacus also important in Africa
3Important Bactrocera species Bactrocera dorsalis – Oriental fruit flyA complex of closely related species:Bactrocera dorsalis (many hosts)Bactrocera papayae (many hosts)Bactrocera carambolae (many hosts)and others (at least 75 different species so far)Bactrocera cucurbitae – melon fly (in cucurbits)Bactrocera tau – also in cucurbitsBactrocera latifrons – solanum fruit flyBactrocera minax – citrus fruit fly
4Important Bactrocera species Bactrocera occipitalis – mango, guava, citrusBactrocera philippinensis – mango, papaya, jackfruitBactrocera umbrosa – jackfruit, breadfruitBactrocera zonata – hosts in Family Rosaceae, including peach, but also other families
5Oriental fruit fly complex For general management purposes, probably OK to regard all members of complex as Bactrocera dorsalisBut where export crops are concerned, exact species must be known – quarantine authorities will insist on it
6Fruit fly life cycleEggs – female lays into fruit with a sharp, pointed ovipositor – may also inject fruit-rotting bacteriaLarvae – three larval instars – feed in fruitWhen fully fed, 3rd instar larva drops to the ground, crawls away (usually into soil) and develops into a pupa (inside hard shell of 3rd instar larval skin, called a puparium)
7Attractants and trapping Male lures – main ones are:Methyl eugenol (ME)CuelureFemale lures (not developed yet)Protein baits – hydrolysed protein including yeastLynfield trapsSteiner traps
10Fruit fly damage Larval tunnelling and feeding damages fruit Bacteria also enter and rot the fruit fasterCrop losses can be from a few per cent to 100%
11Management of fruit flies Cover sprayingAdvantage:EffectiveDisadvantages:Very expensive in pesticideVery time-consuming in labourKills beneficial organisms/harms environmentHarms health of farmer doing the sprayingCan leave chemical residues in fruit
12Management of fruit flies BaggingFruit is covered with a layer of some materialAdvantages:Effective when applied properlyOften increases fruit quality (and price)Materials usually cheapDisadvantage:Very laborious to apply
14Cultural controls Grow less susceptible varieties Harvest fruit early (before fruit fly attack occursCrop hygiene and sanitation – clear away old, fallen, infested fruits
15Protein bait spraying Dilute protein bait is mixed with pesticide Was malathion, now chlorpyrifos, fipronil or SpinosadSmall squirt or splash is applied to leaves of trees scattered through orchardNot necessary to treat every tree – flies are attracted over a considerable distance
16Protein bait spraying Advantages: Disadvantages: Cheap in materials Much safer for health of operatorLess pesticide into environmentNo impact on non-target organismsNo risk of residues when applied correctlyDisadvantages:Still needs labour, though much less than bagging or cover-sprayingMay need to be repeated during fruit cycle
17Protein bait spraying To show farmers how well it works: Put a white sheet on the ground under leaves that have been sprayed with protein bait/insecticideMany dead flies will accumulate!
18Other techniques for control Male annihilationMany blocks impregnated with male attractant and pesticide are distributed widelyMales feed on these and dieFemales remain unfertilised and cannot breedNot suited to individual farmer use
19Other techniques for control Sterile insect techniqueHuge numbers of sterile males are released in an areaFemales mate with them and remain unfertilised – cannot breedMillion dollar operationNot suited to individual farmer use
20Case study in northern Vietnam Peaches were promoted as an alternative to opiumGrow well in climate of northern Vietnam, but 100% of crop was destroyed by Bactrocera pyrifoliaeBait spraying was introduced, and losses now reduced to < 5%Young children have now seen their first ever ripe peaches!
21Contacts and references Paper distributed contains various references to key works on fruit flies that may be of helpAlso key institutions and scientists that may be able to helpDr S. Vijaysegaran – wide expertise in Indian subcontinent, Southeast Asia and Australia
22Methods for identifying fruit flies Morphological versus molecularSee Appendix of paper for some notes on thisReview paper on Bactrocera dorsalis complex:eprints.qut.edu.au/3257/1/3257_1.pdf
23PERCEPTIONS Don’t forget: You may only think about fruit flies The farmer has to think about ALL the problems on the crop!