Квинслендская плодовая муха: биология, вред и методы борьбы.

Species of fly

Bactrocera tryoni, the Queensland fruit fly, is a species of fly in the family Tephritidae in the insect order Diptera. B. tryoni is native to subtropical coastal Queensland and northern New South Wales. They are active during the day, but mate at night. B. tryoni lay their eggs in fruit. The larvae then hatch and proceed to consume the fruit, causing the fruit to decay and drop prematurely. B. tryoni are responsible for an estimated $28.5 million a year in damage to Australian crops and are the most costly horticultural pest in Australia. Up to 100% of exposed fruit can be destroyed due to an infestation of this fly species. Previously, pesticides were used to eliminate B. tryoni from damaging crops. However, these chemicals are now banned. Thus, experts devoted to B. tryoni control have transitioned to studying this pests' behaviors to determine a new method of elimination.

Adult B. tryoni flies are reddish brown in color, have distinct yellow markings and are typically 5–8 mm in length. Adults hold their wings horizontally when walking and flick them in a specific, characteristic manner. The wingspan of B. tryoni ranges from 4.8 to 6.3 mm. B. tryoni may be mistaken for wasps as they appear wasp like.

They are part of a species complex, or a group of morphologically similar but biologically distinct species. Genetic data has suggested that B. aquilonas is simply an allopatric population of B. tryoni. Additionally, B. tryoni mate at night, while B. neohumeralis mate during the day. More pertinently, B. neohumeralis are not pests; they do not destroy crops. The evolutionary relationship between the species within the B. tryoni complex is unknown. Occasionally, there are outbreaks of B. tryoni in southern and western Australia; however, the coastal areas of Australia are relatively isolated from one another due to harsh, dry weather conditions in intervening regions that are unsuitable for B. tryoni. Therefore, other regions of Australia typically remain free of this pest as long as infested fruit is not transported between regions.

After passing through a two week pre oviposition stage following emergence from the pupae, adult females deposit around seven eggs in a fruit puncture, and may deposit up to 100 eggs per day. Fruit punctures are holes in the skin of the fruit that allow the females to access the nutrient rich interior. Females often oviposit in punctures made by other fruit flies, such as the Mediterranean fruit fly (Ceratitis capitata), which results in many eggs occurring in a single cavity. Additionally, B. tryoni females can create their own puncture to oviposit in the fruit, called a "sting".

Eggs hatch into white larvae in 2–4 days under favorable weather conditions. These larvae, or maggots, eat toward the center of the fruit with their cutting jaws, causing it to rot. The maggots may reach up to 9 mm in length; larval development is completed in 10 31 days. At this point, the fruit has likely fallen to the ground. Up to 40 larvae can be reared from a single piece of fruit.

The maggot chews its way out of the remaining fruit and enters the soil, where it enters the pupal stage of development. Pupal development requires various temperature ranges from one week in warmer weather to one month in cooler conditions. The flexible amount of time needed for pupal development has resulted in B. tryoni relative adaptiveness to different environments.

After the pupal stage is complete, adults emerge from the soil. This typically occurs near the end of the summer season. Unlike other fly pests, B. tryoni does not breed continuously, but spends the winter in the adult stage. B. tryoni strongly prefer to oviposit into rotting fruit, although some evidence suggests that they will oviposit into under ripe fruit as well. B. tryoni prefer to select fruits that have an outer layer that is able to be punctured or has already been lesioned. but other data suggest that this symbiosis does not occur as the presence of protein providing bacteria is not consistent throughout B. tryoni populations. Due to this dependence on protein originating from bacteria, it is possible to control the population by providing flies with artificial protein mixed with insecticide.

B. tryoni lay their eggs in fruit. Females prefer to lay their eggs in fruit that is sweet, juicy, and not acidic. The presence of other female flies in pre or post oviposition on a piece of fruit was found to have no bearing on another female's likeliness to land on the fruit; however, female flies were more likely to bore into a piece of fruit that other female flies were currently ovipositing into, therefore increasing the density of larvae within a single piece of fruit. When fruit is available, the flies often do not disperse far distances (only a few hundred meters to a kilometer), but they have been found to travel large distances in the absence of fruit. In addition to lack of resources, adult flies may also move to locate overwintering sites or avoid dry or cold weather. Lure and kill tactics include the use of some sort of bait that attracts the pest, or a lure. This can include semiochemical lures such as pheromones, food attractants, host mimics, or color attractants. Neither the effectiveness of this technique, nor the scientific underpinnings of what protein exactly attracts B. tryoni to the spray, are well investigated. A specific cue lure, Willson's lure, was found to be incredibly effective at attracting sexually mature B. tryoni males. When combined with insecticides, artificially developed cue lures may be an effective elimination method of sexually mature males. While extensive research has suggested this is an effective strategy in other fly species, very few controlled experiments have been conducted to determine the effectiveness of the male annihilation technique in B. tryoni. As of 2014, fenthion was no longer commercially available in Australia.

Containment efforts have included irradiating pupae in order to induce sterility. A study testing the viability of this technique found that sterility was dose independent, meaning that a single ionizing event was enough to render the male sperm sterile. Additionally, it was found that emergence and flight ability remained unaffected by the ionizing event. This indicates that males sterilized via a low dosage of radiation were equally as competitive as males that were not irradiated. If this can be accomplished, this strain can be mass produced and released into the wild without necessitating repeated exposure to irradiation as required in methods such as the sterile insect technique (SIT). This adaptation has allowed them to survive in cooler temperatures and at higher altitudes.

Rising CO2 levels may influence the distribution of B. tryoni''''. Based upon recent studies which utilize computer programs to simulate B. tryoni distribution in the event of rising temperatures, it was predicted that there will be an overall increase in Queensland fruit fly damage, but the fruit flies will re localize to more southerly locations as northern and central Queensland will begin to exceed the maximum habitable temperature of B. tryoni. However, these simulations may not accurately predict the future distributions of B. tryoni as they have exhibited an immense capability to adapt to various conditions. The prediction is also complicated by the uncertainty of how the relative humidity will change in regions across Australia as temperature increases, and B. tryoni survival is heavily dependent upon a humid climate.