Posts Tagged: flies
Fruit Flies
Invasive Fruit Fly Quarantine
What to know as a SJV citrus grower?
Sandipa Gautam
Area Citrus IPM Advisor
UC Statewide IPM Program Operations
Several species of invasive fruit flies that belong to the family Tephritidae are considered serious pests of hundreds of agricultural crops including citrus. These flies lay eggs on or near the fruit surface, and when the maggots hatch, they bore into the fruit, making it unfit for human consumption and causing major losses to fruits and vegetable production. California is experiencing an unusually high number of invasive fruit fly detections in the 2023/24 season and several areas in California are now under a fruit fly quarantine. For many invasive fruit fly species, quarantine is triggered when two or more adult flies are caught in a trap or by a single detection of larvae or pupae indicating a breeding population. Core area is 0.5-mile radius around the detection site and a quarantine area is 4.5-mile radius around each detection.
Counties Currently Impacted by Invasive Fruit Fly Quarantines:
- Oriental fruit fly: Contra Costa, Riverside, Sacramento, San Bernardino, and Santa Clara Counties (Figure 1)
- Mediterranean fruit fly: Los Angeles County (Figure 2)
- Tau fruit fly: Los Angeles County (Figure 3)
- Queensland fruit fly: Los Angeles and Ventura Counties (Figure 4)
Why is fruit fly quarantine concerning to citrus growers?
Citrus is a known host to all invasive fruit fly species. Fruit fly life cycle begins as eggs laid by adult female on surface or under the fruit rind maggots hatch and bore into the fruit and develop inside the fruit (Figure 5). They drop to the ground and pupate. Many fruit fly species are known to overwinter as prepupae or pupae, but some species like Medfly can overwinter in all life stages inside fruit or as pupae on the ground. Adults emerge in early spring and the life cycle continues. Because eggs and immatures can be present inside the fruit, movement of infested fruit may accidentally transport them to a new area where fruit fly has not been detected.
Invasive fruit flies – what to look for?
Four species of fruit flies are currently regulated in California. The adults may look similar to houseflies but are distinctly different in color and the markings on the body. They are about 5-8 mm in size, much bigger than spotted wing drosophila, another invasive species that has been established in California.
- Oriental fruit fly: ~8 mm size, bright yellow colored body with a dark T shaped mark on the abdomen (Figure 1).
- Mediterranean fruit fly (Medfly): ~5-6 mm in size, yellow-light brown body, clear wings with brown bands (Figure 2)
- Tau fruit fly: ~7 mm in size, yellow body with black markings (Figure 3)
- Queensland fruit fly: ~5-8 mm in size, wasp-like body, reddish brown in color with distinct yellow markings, clear wings with band along the top margin.
Figure 1. Oriental fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Contra Costa, Riverside, Sacramento, San Bernardino, and Santa Clara Counties (right).
Figure 2. Mediterranean fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024 – Los Angeles County (right).
Figure 3. Tau fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Los Angeles County (right).
Figure 4. Queensland fruit fly adult with identifying characters (left) and areas in California under quarantine as of January 2024: Ventura County (right).
You can find more information about invasive fruit fly species including interactive quarantine maps, regulatory information and pest profile information below: https://www.cdfa.ca.gov/plant/PDEP/treatment/index.html
Figure 5. Fruit fly larvae are white, legless maggots. They bore into the fruit and feed on pulp. Infested fruit may drop and decay.
What is happening to prevent fruit fly spread?
The California Department of Food and Agriculture (CDFA), in cooperation with the United States Department of Agriculture (USDA) and County Agricultural Commissioners, has initiated local regulatory measures to eradicate and prevent the statewide spread of Queensland fruit fly, Tau fruit fly, Mediterranean fruit fly and Oriental fruit fly. California Citrus Quality Council (CCQC) in coordination with researchers is developing a systems approach that allows for post-harvest treatment of citrus fruit for movement from the core to pack.
What can you do?
- If you are a grower inside the quarantine area, follow regulations about harvesting, processing, or storing fruit. Contact your County Ag Commissioner about the latest regulations, or review FAQs here: https://www.cdfa.ca.gov/plant/fruitfly/docs/Invasive_Fruit_Fly_FAQ_Industry_1-18-24.pdf . If your property is under fruit fly quarantine, follow either pre or postharvest treatment protocols from USDA to move fresh fruit
- Grower outside the quarantine area, stay informed, invest in trapping and pre-quarantine treatments to avoid potential harvest delays should a quarantine be established in the future. For information on prevention and exclusion visit: https://www.cdfa.ca.gov/plant/PE/InteriorExclusion/current_preharvest_treatment.html
- Quarantines boundaries can change rapidly, so it is critical to stay in communication with your local agricultural commissioner.
- Report any suspected invasive fruit fly sightings to CDFA, USDA or your local County Agricultural Commissioner.
- Encourage neighbors, friends, and family to avoid moving any homegrown produce from their properties and to cooperate with agriculture officials working in their area.
- Help spread the “Don't Pack a Pest” message to travelers or those receiving produce in the mail or through other shipping channels.
- Share social media posts created or shared by CDFA, USDA or County Agricultural Commissioners.
Flies in My Avocados
There are all kinds of pollinators in an avocado orchard, not just honeybees. In fact, there is a whole range of native bees that also pollinate the trees. There are nearly 1,600 native bee species in California, and over 30 have been identified in avocado orchards in Ventura County alone .
Another pollinator group is comprised of the Diptera order – flies. This order includes hoverflies and houseflies. Flies can be better at cross-pollinating avocado than honeybees because they move randomly through an orchard between different cultivars, visiting male and female flowers. The effectiveness of flies as pollinators varies between species, but there can often be more than 20 types in an orchard. This means it is likely that some good pollinators will be present, and that pollination can occur whenever the female flowers are open.
In the aforementioned Ventura avocado study, hoverflies are the most common flower visitor.
Housefly
Hoverfly
Avocado Growers, Dont Overlook Flies
Rae Olsson rachel.olsson@wsu.edu 509-335-4846
PULLMAN, Wash. - A tiny bee imposter, the syrphid fly, may be a big help to some gardens and farms, new research from Washington State University shows.
An observational study in Western Washington found that out of more than 2,400 pollinator visits to flowers at urban and rural farms about 35% of were made by flies--most of which were the black-and-yellow-striped syrphid flies, also called hover flies. For a few plants, including peas, kale and lilies, flies were the only pollinators observed. Overall, bees were still the most common, accounting for about 61% of floral visits, but the rest were made by other insects and spiders.
"We found that there really were a dramatic number of pollinators visiting flowers that were not bees," said Rae Olsson, a WSU post-doctoral fellow and lead author of the study published in Food Webs. "The majority of the non-bee pollinators were flies, and most of those were syrphid flies which is a group that commonly mimics bees."
Syrphid flies' bee-like colors probably help them avoid predators who are afraid of getting stung, but they are true flies with two wings as opposed to bees which have four. The flies might have additional benefits for plants, Olsson added, since as juveniles they eat pests like aphids. As adults, they consume nectar and visit flowers so have the potential to move pollen the same way that bees do, though it is less intentional than bees who collect pollen to feed their young.
For the study, the researchers surveyed plants and pollinating insects and spiders on 19 rural farms and 17 urban farms and gardens along the Interstate 5 corridor in Western Washington. They conducted surveys six separate times over two years. In addition to the visits by bees and syrphid flies, they also catalogued more rare visits by other arthropods including wasps, lacewings, spiders, butterflies, dragonflies, beetles and ants--all with visits of less than 4%.
Olsson first noticed the many different non-bee pollinators while working on a bee-survey project led by Elias Bloom, a recent WSU doctoral graduate. The results of this study underscore the need for researchers as well as gardeners and farmers to pay more attention to alternative pollinators, Olsson said, and hoped that similar studies would be conducted in other regions of the country.
"Bee populations are declining, and we are trying to help them, but there's room at the table for all the pollinators," Olsson said. "There are a lot of conservation and monitoring efforts for bees, but that doesn't extend to some of the other pollinators. I think people will be surprised to find that there are a lot more different types of pollinating insects - all we really need to do is to start paying a little more attention to them."
The study also noted pollinator differences between rural and urban spaces. Observations sites in urban areas showed a greater diversity of pollinators corresponding with the wider range of plants grown in city gardens and smaller-sized farms. Rural farms with their larger fields of plants had a greater abundance.
For every grower, urban or rural, who is interested in increasing the number and diversity of pollinators visiting their fields or gardens, Olsson recommended increasing the variety of flowering plants.
Making sure that something is flowering all throughout the season, even if on the edge of a field, will support the biodiversity of pollinators because their different life stages happen at different times of the year.
"Some pollinators like certain butterflies and moths are only present in a pollinating form for a small period of time," Olsson said. "They may only live for a few days as adults, so when they emerge and are ready to pollinate, it's good to make sure that you have something for them to eat."
Read On: https://news.wsu.edu/2021/06/22/bee-impersonating-flies-show-pollinator-potential/
Photo: Not a bee, a hover fly or syrphid fly
syrphid adult
Moths, Flies, Beetles Pollinating Avocados? O, MY!
And doing it in the dark?
In a recent paper, David Pattemore and associates reveal some fairly different observations about avocado flowering. One, that the female stage can be open and potentially receptive to pollination at night. And Two, that moths and crane flies amongst other nocturnal insects are visiting the flowers and carrying pollen!!! These are two very new observations, made possible by the digital world we live in.
Of course, insect visitation doesn't mean fruit set. Is there pollination, transfer of pollen to the female stage? Is there enough pollen? Is it the right pollen? Is it the right temperature for fertilization to occur? Whatever else needs to happen for fruit set, is it happening?
But these observations are opening up new discussion topics for the avocado world.
LOW OVERNIGHT TEMPERATURES ASSOCIATED WITH A DELAY IN ‘HASS' AVOCADO (PERSEA AMERICANA) FEMALE FLOWER OPENING, LEADING TO NOCTURNAL FLOWERING
David Pattemore1,2*, Max N. Buxton1, Brian T. Cutting1, Heather McBrydie1, Mark Goodwin1, Arnon Dag3
1The New Zealand Institute for Plant & Food Research Limited, Ruakura Research Centre, Hamilton 3210, New Zealand
2School of Biological Sciences, University of Auckland, Auckland, New Zealand
3Gilat Research Center, Agricultural Research Organization, 85280, Israel
Abstract—Avocado (Persea americana) has synchronously protogynous flowers: flowers open first in female phase before closing and opening the next day in male phase. Cultivars are grouped based on whether the flowers typically first open in female phase in the morning (type A), or in the afternoon (type B). However, it is known that environmental factors can alter the timing of flower opening, with cold temperatures being shown to affect the timing of flowering. The aim of this study was to investigate how low spring temperatures in New Zealand affect the flowering cycle of commercial avocado cultivars, focusing primarily on the receptive female phase of ‘Hass', a type A cultivar. Time-lapse photography was used to assess flower opening times of ‘Hass' over three years. Decreasing minimum overnight temperatures were associated with a delay in the timing of ‘Hass' female flower phases and resulted in nocturnal flowering of both male and female phase flowers. We recorded insects visiting female flowers at night, and some nocturnal flower visitors collected were carrying avocado pollen. Our study suggests that nocturnal pollination needs to be considered for avocados grown in temperate regions. Furthermore, as the timing of the female phase of ‘Hass' varied significantly with overnight temperature, the activity patterns of potential pollinators need to be considered to ensure adequate pollinator activity across the range of times in which ‘Hass' flowers are receptive.
Eight different invertebrate orders were captured from avocado flowers at night. Coleoptera, Diptera and Lepidoptera were the most frequently caught floral visitors, but it was coleopteran, dipteran and neuropteran individuals that carried the greatest number of pollen grains on average. This is an important distinction to make, as not all floral visitors behave as pollinators: visitation does not necessarily infer pollination. Species such as Costelytra zealandica (Coleoptera), Micromus tasmaniae (Neuroptera), along with Tipulidae and Sylvicola species (Diptera) may be especially important, as these were both frequently caught and often carried a high number of pollen grains. Compared with diurnal pollination, nocturnal pollination is poorly understood and relatively little research in New Zealand has tested assumptions that nocturnal floral visitors can act as pollinators.
This is an interesting read and introduces further areas of pursuit to understanding what brings on fruiting in the wild avocado.
Read On:
click on Download this PDF file
Rhapsa scotosialis – a potential avocado pollinator?
Rhapsa scotosialis female
Oriental Fruit Fly Quarantine in LA County
SACRAMENTO — A portion of Los Angeles County has been placed under quarantine for the Oriental fruit fly following the detection of nine flies in the Hollywood area. The quarantine zone measures 75 square miles. A link to the quarantine map may be found here:https://www.cdfa.ca.gov/plant/off/regulation.html
“California's fruit fly season extends from late summer through the fall,” said California Agriculture Secretary Karen Ross. “These pests like Southern California for some of the same reasons other travelers do: the pleasant climate and the tremendous variety of food. Fortunately, with the help of local residents, we have a great track record of eradicating these infestations.”
To prevent the spread of fruit flies through homegrown fruits and vegetables, residents living in the fruit fly quarantine area are urged to not move any fruits or vegetables from their property. Produce may be consumed or processed (i.e. juiced, frozen, cooked, or ground in the garbage disposal) at the property where it was picked.
The most common pathway for these pests to enter the state is by “hitchhiking” in fruits and vegetables brought back illegally by travelers as they return from infested regions around the world or from packages sent to California. To help prevent infestations statewide, officials asks residents to refrain from bringing or mailing fresh fruit, vegetables, plants, and soil into California unless agricultural inspectors have cleared the shipment beforehand.
While fruit flies and other invasive species threaten California's crops, the vast majority of them are detected in urban and suburban areas.
“That's why it's important for residents to cooperate with quarantine restrictions and allow authorized agricultural workers access to properties to inspect fruit and oriental fruit fly traps for signs of an infestation,” said Secretary Ross.
Following the principles of Integrated Pest Management (IPM), the California Department of Food and Agriculture (CDFA) uses a “male attractant” technique in its eradication effort for this pest. This approach, which has successfully eliminated dozens of fruit fly infestations in California, significantly reduces the amount of insecticide required to eradicate the population, and only targets the fruit flies – no other insects or animals are harmed. The treatment program is being carried out over several square miles surrounding the sites where the oriental fruit flies were trapped.
The oriental fruit fly is known to target more than 230 different fruits, vegetables, and plants. Damage occurs when the female fruit fly lays her eggs inside the fruit. The eggs hatch into maggots and tunnel through the flesh of the fruit, making it unfit for consumption.
The oriental fruit fly is widespread throughout much of the mainland of Southern Asia and neighboring islands including Sri Lanka and Taiwan, and has invaded other areas, most notably Africa and Hawaii.
Residents with questions about the quarantine may call the CDFA Pest Hotline at 1-800-491-1899.
—California Department of Food and Agriculture
Photos: OFF adults and Grapefruit infested with larvae of oriental fruit fly, Dacus dorsalis.
oriental fruit fly image
oreintal fruit fly citrus