Taxonomic name: Ceratitis capitata (Wiedemann, 1824)
Synonyms: Ceratitis citriperda MacLeay
, Ceratitis hispanica De Brême, Paradalaspis asparagi Bezzi, Tephritis capitata Wiedemann
, Trypeta capitata Wiedemann, 1824
Common names: medfly (English), Mediterranean fruit fly (English)
Organism type: insect
Ceratitis capitata is considered a major tephritid fruit fly pest of economic importance attacking more than 300 different hosts, primarily temperate and subtropical fruits. The medfly as it is commonly called has invaded many countries and caused major economic losses for fruit farmers. C. capitata has the ability to tolerate cooler climates better than most other species of fruit flies. It lays its eggs under the skin of fruit, usually around already broken skin. Due to this reproduction habit, C. capitata thrives in agricultural areas where fruit is left out and becomes damaged. It spreads to new locations via exports and the local sale of fruit that contains eggs.
Medfly has the ability to tolerate cooler climates better than most other species of fruit flies (Mau and Kessing 1992). Thomas et al. 2001, state that some adults may survive up to six months or more under favourable conditions of food (fruit, honeydew, or plant sap), water, and cool temperatures.
Broughton & De Lima (n. d.) state that “In winter, the [Med]fly may become inactive in cold areas. Medfly can overwinter as adults, as eggs and larvae (in fruit), or as pupae in the ground. Adult Medflies are active in winter when temperatures exceed 12 ºC. ” They also recommend that any control methods should begin in Spring, as the temperature increase allows overwintering flies to become active, to prevent population sizes from increasing rapidly to problematic levels.
Ceratitis capitata is a serious pest to many crops. Damage to crops caused by C. capitata results from:
Larval feeding in fruits is the most damaging. Mature, attacked fruits may develop a water soaked appearance. Young fruits become distorted and usually drop. The larval tunnels provide entry points for bacteria and fungi that cause the fruit to rot. These maggots also attack young seedlings, succulent taproots, and stems and buds of host plants.
- Oviposition in fruit and soft tissues of vegetative parts of certain plants
- Feeding by the larvae
- Decomposition of plant tissue by invading secondary microorganisms.
Trapping for detection of populations; excluding populations by using foliage baits and chemical sprays and release of male sterile medflies to reduce populations require a great deal of resources and can have significant economic implications. Medflies are serious quarantine pests that also affect global trade. The presence of medflies often requires host crops to undergo quarantine treatments or other disinfestation procedure of certification of fly-free areas. The costs of such activities and phytosanitary regulatory compliance can be significant.
Cohen & Yuval (2000) point out that “C. capitata is polyphagous and, as such, uses the various hosts in its environment as stepping stones, moving from one to another as fruit mature throughout the season.” This gives Medfly the ability to destroy an area’s production of many fruits, and means that damage is not limited to just one fruit species, while also providing medflies with refuges from control efforts, serving as a source of reinfestation to surrounding private or commercial plots.
“Under International Plant Protection Convention (IPPC) Standards, C. capitata is considered to be a pest that is ‘transient, actionable, and under eradication’ in the United States’ (NAPPO, 2008). All non-European Tephritidae, including Ceratitis capitata, are regulated as quarantine pests by the European Union, and fruit being imported into Europe must be free of all life-stages of this pest (Rossler & Chen, 1994).
Native range: The Mediterranean region and north Africa (Mau and Kessing 1992), sub-Saharan Africa (White & Elson-Harris, 1992).
Known introduced range: North America, South America, and Australia (Thomas et al. 2000)
The climate matching model CLIMEX was used to infer the climatic requirements of the medfly using observed geographical range in the Mediterranean region. The study indicated that the distribution of the medfly was restricted by climatic factors - dryness in the south of Spain and Portugal and northern Africa; and by the cold to the north in Europe. The model was then used to map the potential areas of distribution in Argentina and Australia. The results demonstrated agreement with observed distribution in Argentina and historical distribution in Australia. There was however disagreement with current distribution in eastern Australia, this was attributed to displacement of the medfly by another fruitfly species Bactrocera (Dacus) tryoni (Froggatt) ( Vera et al. 2002 ).
Despite its wide range of potential hosts, in some areas of the world the medfly has been forced into high-elevation areas, which have less host plants, due to being out-competed by other fruit fly species, such as the Oriental fruit fly, Bactrocera dorsalis in Hawaii and the Natal fruit fly, Ceratitis rosa Karsch in Madagascar (Headrick & Goeden, 1996).
Introduction pathways to new locations
Agriculture: Insects lay their eggs under the skin of fruit (Mau and Kessing, 1992).
Ignorant possession: Insects lay their eggs under the skin of fruit (Mau and Kessing, 1992).
Local dispersal methods
Agriculture (local): According to Mau and Kessing (1992), the fly lays it's eggs under the skin of fruit and usually in a spot where the skin is already broken. So more damaged fruit is associated with more flies. C. capitata also spreads by local sale of infested fruit.
On animals (local): Ceratitis capitata can fly short distances, but winds may carry it a mile or more away (Mau and Kessing, 1992).
Preventative: Early detection is very important to prevent establishement of populations. Detection programmes using lures and attractants and constant monitoring are required to ensure early detection. Countries which export fruit have to make sure that a comprehensive detection programme is maintained and that strict quarantine procedures are in place to prevent the spread of the pest to flyfree zones. Control options should be started early in spring when temperatures start rising and overwintering adults become active and new adults emerge from the ground (medfly can overwinter as adults, as eggs and larvae in fruit or in their pupal form in the ground).
Chemical: An important measure to be taken to ensure success of any chemical control is the disposal of unwanted and medfly infested fruit. Several methods suggested for disposal are: soaking fruit in water topped by a layer of kerosene( to cut off oxygen supply); freezing fruit for a few days; cooking or pureeing fruit. Burial is not recommended at depths of less than 18 inches as medfly can survive a burial . The two main control methods recommended are foliage baiting and cover spraying. The female medfly requires a source of protein for the maturation of her eggs which she sources from fruit juices, bacteria etc from nature. The foliage bait combines a source of protein with an insecticide and is attractive for both the male as well as the female medfly. The bait is usually applied in the morning hours and applies as a spot application aimed at the middle of the trees. Cover spraying controls all life stages through contact and penetrative action. Spraying is carried out when fruits are half or two thirds in size. Depending on the level of infestation the two methods can be used together.
Physical: Trapping is not recommended as a control option but is useful for detection. The three types of traps used are those used to trap the male medfly which consists of a parapheromone plus insecticide, a trap for the female medfly using a lure and a wet trap used for both the male and the female medfly which consists of a food source ( a sugar or protein) plus an insecticide. It is good to remember that other insects can also be caught in these traps.
Biological: A technique called the sterile insect technique (SIT) is used to contain and exclude populations of medfly. The goal of SIT is to release sterile males to mate with any introduced wild females, resulting in the production of infertile eggs. In California, the SIT program is changing from the release of both male and female sterile flies (bisexual strains) to the use of sterile flies from “male-only” strains (Jang et al. 2003).
Please follow this link for detailed information on the management of the Ceratitis capitata.
The medfly is known to attack over 300 different hosts, primarily temperate and subtropical fruits (Liquido et al. 1991 ). It is thought that in the absence of control, in Western Australia, “Medfly would infest 100 percent of susceptible fruit such as apricots, nectarines, peaches and mandarins and to a lesser extent, fruits such as apples and pears” (Broughton & De Lima, n. d.). The only fruit which would survive unaided are thought to be fruit fly tolerant varieties of fruit, and stone fruit maturing early.
As C. Capitata is polyphagous, it uses the various suitable hosts found within in its environment as stepping stones, and often moves from one to another as fruit mature throughout the season (Cohen & Yuval, 2000). The fruit ripening sequence of an area is important in terms of early detection, allow the first Medfly of a season to be detected as early as possible (in the earliest-ripening fruit type).
Newly emerged adults are not sexually mature. Males often show sexual activity four days after emergence, and copulation which can occur at anytime has been observed five days after emergence. Most females are ready to mate from 6 to 8 days after emerging from the pupa. Eggs are very slender, curved, 1mm [1/25 inch] long, smooth and shiny white. They are deposited under the skin of fruit that is just beginning to ripen, often in an area where some break in the skin has already occurred. Several females may use the same deposition hole with 75 or more eggs clustered in one spot. Each female will deposit 2 to 10 eggs. Eggs hatch in 1.5 to 3 days in warm weather. Females lay 1 to 10 eggs in a cavity 1mm [1/25 inch] deep. She may lay as many as 22 eggs per day and as many as 800 eggs during her lifetime (usually about 300) (Mau and Kessing, 1992). C. Capitata has the highest net reproductive rate of four species of tephritids (which are ecologically very similar) which currently inhabit La Réunion (Duyck et al. 2007).
Larvae begin feeding almost immediately after hatching. Tunnels are formed, but the larvae often feed together in the same vicinity until they are nearly fully grown. Larvae pass through three larval stages (instars) before they emerge from the fruit.
They may emerge in large numbers just after daybreak and pupate in the soil or whatever is available. Minimum duration of the pupal stage is 6-13 days when the mean temperature ranged from 24-26 C [76-79 F]. Pupae usually develop in soil an inch or two below the surface.
Adults emerge from the pupal cases in large numbers early in the day during warm weather and more sporadically in cooler weather. Females usually die soon after they stop ovipositing. The length of time required for C. Capitata to develop from egg to adult is about 21-30 days under tropical conditions. According to Thomas et al. (2001), “adults die within four days if they cannot obtain food. Usually about 50% of the flies die during the first two months after emergence. Some adults may survive up to six months or more under favourable conditions of food (fruit, honeydew, or plant sap), water, and cool temperatures. When host fruit is continuously available and weather conditions favourable for many months, successive generations will be large and continuous. Lack of fruit for three to four months reduces the population to a minimum.”
Modelling of medfly dispersal distances done by Meats & Smallridge (2006) found that the majority (90%) of medflies displaced only 400 – 700m.
Reviewed by: Eric Jang
U.S. Pacific Basin Agric. Res. Center
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
Last Modified: Friday, 2 April 2010