Balance in the Garden: Can Fruit Flies Help Weed Control?

Dateline: February 7, 2015*

A tiny fruit fly on Bidens alba

Funny that when I think of fruit flies I immediately feel the need to swat something around the bowl of fruit on the counter or rinse the nearest apple. They really don’t conjure up visions of garden weeds.

But, if you think of fruit in terms of a dictionary definition:

The ripened ovary or ovaries of a seed-bearing plant, together with accessory parts, containing the seeds and occurring in a wide variety of forms.”

you might just come around to realizing that a fruit fly can play a role in keeping some weedy plants in check.

According to the USDA many species in the Fruit Fly (Tephritidae) family are economically important. Some damage fruit and other crops, while other species are used as agents of biological control to reduce populations of pest weed species.

Meet my new fruit fly friend (Dioxyna sp. likely picciola). A pretty little thing with picturesque wings, I spotted this miniscule fly on some Florida native Spanish Needle flowers (Bidens alba). Mind you, it is so tiny that I didn’t really see it with my naked eye. I saw some movement on the flower so I took a close-up photo and investigated my find via the zoom of the computer screen.

Mating pair of fruit flies

I thought my friend was just enjoying the nectar of this “pollinator’s dream” native plant, but a few days later I captured a photo of a mating pair and come to find out that this particular species of diptera may be using the B. alba as a host plant. It may also use other members of the Aster family such as Coreopsis sp.

So, the fly I initially saw might have been laying eggs in the fruits of the flowers, which is not to say they aren’t drinking some of the sweet elixir at the same time.

They have such beautiful wing markings

If they indeed use the seed as a host, well, it would make sense that this might inhibit some seed from being viable, thus keeping down the numbers of fertile individuals available to be scattered by wind, rain or animal for replanting. Mom Nature…such a smarty with her built in checks and balances!

Is there a resulting cause and effect from the human inclination to control insects in the quest for unblemished, perfect fruit? Does killing a fruit fly that might nosh on the fleshy part of a plum also kill the fruit fly that noshes on the seeds of a plant with aggressive tendencies?

We need to rethink our approach in the garden. Stop worrying about the perfection of flowers and minor spots on fruits and start thinking about the overall roll of flora and fauna in the scheme of things.

Rejoice not only when a butterfly caterpillar chews on your plants, but also rejoice when ANY of the arthropods chew away. A sustainable, working garden should be the goal.

Spanish Needles (Bidens alba) have prolific amounts of seeds, so having a readily available biological control agent is great

In addition, these flies will do double duty and serve as food for predators such as reptiles, amphibians and spiders and act as hosts for parasitic wasps and others. That’s what makes the world go round.

Crab Spider on B. alba: waiting for a fruit fly meal?

Consider that each element in your beautiful wildlife garden works hand in hand with other elements, so it is important to allow each element to perform the job intended and not alter it so drastically through use of chemicals to control insects we may find offensive. A pest of one may be a meal for another.

*This tale was originally published by Loret T. Setters on February 7, 2015 at the defunct national blog beautifulwildlifegarden[dot]com. Click the date to view reader comments.

Resources:

General Reference for Fruit Fly ProgramsTephritidae, Developed by: USDA,APHIS,PPQ, Pest Detection and Management Programs, Prepared by: Jeffrey N.L. Stibick,Date: March, 2004

 

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