Know And Protect Beneficial Insects
March 1, 2013 Contrary to popular belief, not all insects are “bad bugs.” In fact, only a small percentage of insects are actually harmful to humans in any way. Many insects are actually beneficial to humans in agricultural settings as well as general well being. These insects are categorized as beneficial because they are a predator, parasitoid, or a competitor of pest insects.
Because there are so many beneficial insects out there, it is important to recognize them when making pest control decisions. IPM or Integrated Pest Management’s first step is correct identification. Many times we may see something we think of as a pest, when in reality it may be the exact opposite being a beneficial that is feeding on our pest problem.
Lady Beetle
The lady beetle is one of the most beneficial insects found in Florida. Adult lady beetle is very recognizable to most people with the orange or red color and black markings or spots. Others may be found with black color and yellow or red markings or spots. The body shape is oval and range in length from 1/16” to ½.” The larvae are not as recognizable as the adult, and some may get confused if not careful to identify it correctly. They are somewhat flattened and elongated with the abdomen narrowing to the rear end of the insect. The coloring is usually black or dark with bright spots or bands on the abdomen. The Lady Beetle adult and larvae are frequently seen feeding on aphid populations as well as scale, mealybugs, and mites.
Lacewings
Another common predaceous insect is lacewings. This insect as an adult has a long thin body 3/4“ with wings that set vertically along its back, with green color and cooper eyes. The adults can be either predaceous or may not be depending on species. The larvae of lacewing, like the lady beetle, are very predaceous and feed on many soft-bodied insects such as aphids and mealybugs. Because of their habit of feeding on aphids, the Lacewings have earned the common name “Aphidlion.” The larvae are characterized by their elongated bodies with the sickle shaped mandibles. Another important feature to identify with Lacewing species is their unique eggs that hang on to a ¼” stalk off the foliage surface.
Big-Eyed Bugs
The main characterization of this beneficial insect is its large eyes, of course where the insects name comes from. Many times this insect is found on the surface of the soil feeding on chinch bugs. The big-eyed bug is usually black with silver/metallic looking wings, and has a somewhat flattened wide body.
Stink Bugs
When a producer hears stink bugs they cringe a little bit, because of how difficult some of the species are to control. There are both harmful pest stink bugs as well as predaceous species that are beneficials. Stink bugs have various different colors but some of the common ones are brown, green, or gray. To identify a predaceous type stink bug from a pest types look for spines that project from the thorax. Other characteristics are shorter beaks and rounded shoulders. Their insect of choice to attack is caterpillar species, though they prey on many different types of insects.
How To Attract, Maintain Beneficial Insects
There are many plants that are used to attract beneficial insects to our fields in order to use the earth’s built-in pest control mechanism. Once the producer figures out what kind of plants that these beneficial insects prefer, the environment of the production areas can be altered to a conducive habitat for the beneficial insect.
One plant characteristic that beneficial insects are attracted to is Extrafloral Nectaries (EFN). EFN is a nectar producing gland of the plant other than the flower, which is commonly thought of as the primary source of nectar from a plant. The EFN are located in several different plant parts (petioles, fruit, bracts, etc.) depending on plant species. The nectar produced is 95% sugar and 5% other nutrients. The function of the EFN is thought to be for ridding supplemental nutrients or to attract beneficial insects for plant defense. There are several Florida grown plants that exhibit EFN such as cotton, sunflower, beans, and elderberry. To learn about more plants with EFN visit http://edis.ifas.ufl.edu/in175.
Avoid Some Chemicals
When trying to promote the growth of the beneficial insect populations, there are certain chemicals that should be avoided. In any Integrated Pest Management program, chemical control is a last resort option. This means that the other tools should be used prior to applying chemicals, such as mechanical, cultural, and biological control methods. If chemical action must be taken it is advisable for the producer to have a well thought out pest management decision. The least-toxic chemical control should be used that targets the pest problem but does not harm the non-target organism, namely the beneficial populations.
Chemicals that are non-selective or broad spectrum insecticides tend to kill all insects that are in the application areas and should be avoided if possible. Pyrethroids are generally not toxic to most beneficial lacewing species, but can be deadly to predatory mites and other parasitoids. Organophosphates typically are harmful to all natural enemy insects. In general, pesticides that are newer chemistries on the market tend be less toxic, more selective, and target the specific pest problems. Many may feel that the cheaper older chemistries is the way to go, but if a producer really pays attention and uses the IPM strategies, they could have less sprays in the growing season.
Banker Crops
Banker crops are a good way to promote beneficial predators to your production areas. A banker crop is a plant species that is put in place to give the beneficial insects a food source other than the pest insect within your crop, so you can assure you have a source of food even when pest pressures are down. The best example of the banker crop is the crape myrtle (Lagerstroemia indica). The crape myrtle is host to an aphid species that only inhabits and feeds on crape myrtle. This is the reason that the crape myrtle is such a good candidate for a banker crop. With the aphid only feeding on the crape myrtle, there is no threat of that species of aphid attacking your cash crop. So the crape myrtle turns into an open buffet for beneficials that feed on aphids. Presently, banker crops are used more in protected agriculture situations such as greenhouses, but there is a lot of promise for the future of banker crops.
For more information on IPM or beneficial insects, visit http://ipm.ifas.ufl.edu.
Sources:
- D.E. Short, F.A. Johnson, and J.L. Castner. 2002. Beneficial Insects Sheet 1 & 2. Florida Coop. Ext. Serv., IFAS, Univ. Florida, Gainesville, 32611. SP89.
- Mizell, R. F., Many Plants Have Extrafloral Nectaries Helpful to Beneficials. Published August 2001. Revised July 2009. Reviewed June 2012.ENY-709 (IN175), Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
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