Name: Video: Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection
Uploaded: 2023-07-28T15:00:00
Duration: 3 min 11 s
Description: 462 Views. Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection

mushing, sieving, and sugar floatation for fruit fly larvae collection

The Mushing, Sieving, and Floating Method for Detecting Fruit Fly Larvae

Tephritid fruit flies are among the most destructive agricultural pests, with the genera Anastrepha, Bactrocera, and Ceratitis posing the greatest risk1. Many areas are at high risk for exotic fruit fly establishment, based on 1) historical incursions and associated delimitation and eradication programs, 2) the high arrival rate of fruit fly host material at ports of entry, and 3) climatic conditions favorable for the establishment of reproducing populations. The state of California experiences multiple incursions and detections of tephritids annually2. There have been more than 200 incursions and eradication programs against tephritids globally over the last century, and this has accelerated significantly in recent decades3. Though the vast majority of these programs are successful in eradicating the invading fruit fly3,4, the economic and environmental burden of these invasions remains still high, and the possibility of establishment is always present; a recent catastrophic example is the infection of Bactrocera dorsalis in the African continent5.
During emergency fruit fly programs, a concerted effort is made to detect and control breeding populations of the invading species. For example, the state of Florida responds to tephritid incursions by applying soil drenches (under the dripline of fruit-bearing host plants) and removing host fruit in a 200 m radius around sites where mated females and/or larvae are found6. These actions and tactics serve to kill larvae and pupae in the soil and remove any eggs and larvae from fruit within the area. In some eradication programs, a significant amount of host fruit is removed. In 2015, over 100,000 kg of fruit was destroyed during the B. dorsalis eradication program in Florida6. The economic losses to growers and associated industries in the quarantined area alone were estimated to be over $10.7 million7.
To find tephritid larvae in the quarantine areas, a small team of entomologists collect host fruits in a 200 m radius around a female fly detection area and cut and visually inspect each fruit for larvae6. With limited staff resources and hundreds of possible hosts, the task becomes difficult, particularly in the areas where plant diversity in both commercial production areas and residential yards is high. In addition, larvae may be missed when cutting host fruits. In a study evaluating fruit cutting at the ports of entry, cutting fruit was found not to be as effective in detecting A. suspensa when compared to holding the infested fruits for several weeks and counting the larvae and pupae found in the pupation substrate8.
There are&#160;alternatives to&#160;fruit cutting for detecting an infestation9,10,11,12,13. For example, a brown sugar floatation and a hot water method are both accepted procedures used to detect western cherry fruit flies in harvested cherries9,10. The brown sugar method involves placing crushed fruit in sugar water solution and collecting larvae that float to the top. The brown sugar floatation method was developed specifically to meet regulatory rules for exported cherries, which require packing houses to monitor for quarantine fruit fly pests. There is also an approved US-Canada blueberry certification program that includes brown sugar water floatation, salt water floatation, or boiling to support phytosanitation14. When testing the accuracy of sugar and hot water floatation, researchers used the sieving method to determine how many larvae are missed9,10,11,12,13. A study showed that mixing crushed blueberries in a salt solution and filtering the solution through a reusable coffee filter was four times better in detecting Drosophila suzukii larvae than visually inspecting the surface of salt and sugar solutions14. In addition, gas chromatography was used for the detection of A. suspensa larvae in citrus15. These approaches have not been tested for applicability in field surveys.
Our goal was to develop and test a method to find tephritid larvae in the field using sieving and sugar water floatation. This method allows the more efficient detection of immature fruit flies than the traditional fruit cutting method, supporting the timely control of breeding populations during fruit fly eradication programs.

Author Spotlight: Sieving Fruit Pulp to Detect Immature Tephritid Fruit Flies in the Field  

Sieving Fruit Pulp to Detect Immature Tephritid Fruit Flies in the Field

Watch this Scientific Journal Video about Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection at JoVE.com

Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection  

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462 Views. Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection

Video: Mushing, Sieving, and Sugar Floatation for Fruit Fly Larvae Collection  

Fruit flies of the Tephritidae family are among the most destructive and invasive agricultural pests in the world. Many countries undertake expensive eradication programs to eliminate incipient populations. During eradication programs, a concerted effort is made to detect larvae, as this strongly indicates a breeding population and helps establish the spatial extent of the infestation. The detection of immature life stages triggers additional control and regulatory actions to contain and prevent any further spread of the pest. Traditionally, larval detection is accomplished by cutting individual host fruits and examining them visually. This method is labor intensive, as only a limited number of fruit can be processed, and the probability of missing a larva is high. An extraction technique that combines i) mushing host fruit in a plastic bag, ii) straining pulp through a series of sieves, iii) placing retained pulp in a brown sugar water solution, and iv) collecting larvae that float to the surface was tested. The method was evaluated in Florida with field-collected guava naturally infested by Anastrepha suspensa. To mimic low populations more representative of a fruit fly eradication program, mangos and papaya in Hawaii were infested with a known, low number of Bactrocera dorsalis larvae. The applicability of the method was tested in the field on guava naturally infested by B. dorsalis to evaluate the method under conditions experienced by workers during an emergency fruit fly program. In both field and laboratory trials, mushing and sieving the pulp was more efficient (required less time) and more sensitive (more larvae found) than cutting fruit. Floating the pulp in brown sugar water solution helped detect earlier instar larvae. Mushing and sieving fruit pulp of important tephritid hosts may increase the probability of detecting larvae during emergency programs.

Increasing the detection of immature tephritid fruit flies in the field can trigger timely efforts to eliminate populations of these destructive pests. Detecting late instar larvae is faster and more accurate when mushing host fruit in a bag and passing the pulp through a series of sieves than hand cutting and visual inspection.

Fruit flies of the Tephritidae family are among the most destructive and invasive agricultural pests in the world. Many countries undertake expensive ...