January 2014 Newsletter (vol.25)   >>   Good Bug, Bad Bug

 

 

By Aaron Fields

 

Bugs get a bad rap. From a young age we view bugs as intrusive, annoying and disgusting. They are often unwelcome guests at picnics, in homes, and in gardens and greenhouses. Many bugs cause damage to crops, flowers and trees ruining countless hours of hard work and growth. While many people view bugs in a negative light, several bugs have very important roles in our world.

 

In the past few years, bee keepers and growers began noticing entire colonies of bees disappearing for no apparent reason. This became known as Colony Collapse Disorder and it is the result of several intricate factors. An acute view of this issue may cause those allergic to bee stings or those afraid of bees to rejoice, however a more informed perspective would show how globally devastating this loss could be. An estimate by the United Nations in 2005 placed a value of 200 billion dollars worth of agriculture that relies on bees as the main pollinator. This means that the decrease in bees results in a decrease in production of some food crops. This may lead not only to a potential huge financial loss but also a drop in the availability of produce around the world. While this is an extreme case, it brings to light what an important role insects play in our lives.

 

While the above example shows how removing an insect can cause large scale problems, let’s look at how adding insects can help solve problems. In the horticultural world there is a constant battle between grower and pest; enter the bad bugs. Aphids, whitefly, thrips and mealy bugs are just a few of the pests that can cause widespread damage to fields and greenhouses. These insects feed on parts of the plant or introduce dangerous pathogens that can ruin foliage and destroy produce.

 

More often than not, the growers use pesticides as the weapon of choice in the assault against arthropods. These chemicals can be very effective but have side effects and limitations. Chemical applications are dangerous to workers and prevent entry into the growing area for hours at a time. Misapplication of chemicals can do more harm than good to both plants and people. Overuse of chemicals introduces a resistance to the treatment and possible creation of superbugs which are immune to certain pesticides. Pesticides can harm both pests and beneficial insects, doing more harm than good in the long run. With all of these negative aspects, it is no wonder that growers in greenhouses and backyard gardens are searching for safer ways to control and prevent bad bugs.

 

Enter the good bugs. Just as most animals are both predator and prey, that circle of life pertains also to the insect world. Almost every bad bug has a good bug that is just waiting to attack. Growers can purchase these for use in their gardens and greenhouses as an alternative to spraying chemicals. These good bugs, or beneficial insects, use the bad bugs for food sources or as a host for certain stages of their lifecycle. In either case, the bad bugs are killed and your plants are a little safer.

 

Some of these beneficial bugs are predators which hunt down and feed on the pests. Species such as the whitefly destroyer Dephastus catalinae, the aphid midge Aphidoletes aphidmyza, and predatory mites can all be introduced to clear out any bad bugs in your growing area. Most of these predators are specific feeders meaning they will only search out and eat specific prey. Once that prey is gone, your beneficial bugs will leave the area in search of a new food source. While this is good for you in that your bad bugs have been decimated, know that you will have to introduce new predators if the pests come back. There are a few generalist feeders among beneficial insects that will feed on a number of species and may have a more lasting effect.

 

There are also parasitic good bugs. These bugs, such as Encarsia formosa which target greenhouse whiteflies, are introduced and will search out and use a host species to facilitate their lifecycle. In the case of Encarsia, they are introduced on cards which contain thousands of microscopic eggs. When these eggs hatch, they will seek out whitefly nymphs, feed on them and deposit eggs inside the body of the host whitefly. Not only does this take care of the pest problem, but it also increases the population of the beneficial insect. As with predatory beneficials, parasitic insects are host specific and numbers will subside as the pest population drops.

 

Now that we have talked about how beneficial insects can be introduced to control pests, let’s consider some of the changes that growers may have to make to incorporate a beneficial program. While beneficials can prove effective and safe, they take an intricate approach to introduce properly.

 

You must have a complete understanding of the bad bug and the good bug in order for this approach to be effective. This starts with proper identification of pests on your plants. It is often a good idea to seek the consultation of your local agriculture extension or garden expert. Once you know the pest, take some time to understand them. Read articles to familiarize yourself with their lifecycle. Take some time to figure out which plants you have that the pest prefer and if you notice them being more active at a certain time of the day. Once you have this information, it will be easier for you to introduce the perfect beneficial insect for control.

 

Also consider that a beneficial program can be expensive and very time consuming. Think about the economic or production threshold that you would like to maintain. You could have bad bugs all over your garden but if they aren’t doing enough damage then it may not be worth it to implement a beneficial program. It takes time to monitor both your pest population and your beneficial bug population. Putting out sticky traps, scouting and keeping records all take a lot of scheduling to do correctly. Know also that there may very well be beneficial insects already at work in your greenhouse or garden and take that into consideration before any chemical application.

 

If you do decide to bring in some good bugs to fight the good fight, know that you probably cannot apply any pesticides, synthetic or natural, while the beneficials are at work. There is a great chart in Hummert’s Helpful Hints along with other helpful beneficial information. It also may take a week or so for the good bugs to have an effect on the bad bug population. If the population of pests is out of control and approaching your threshold you may want to consider a pesticide application to help knock down the pest before introducing beneficials.

 

Any order of the good bugs will be delivered to you in a few days from the time it is placed and shipped with all the precautions to keep them alive in transit. Some beneficials like ladybugs can be released a little at a time while the rest are kept in a refrigerator. Others like the aforementioned Encarsia need time and certain environmental conditions to hatch before they become effective. All good bugs will come with specific instructions and you should take good care to follow these prudently.

 

As with any battle against pests in growing areas, be sure to keep perspective. Know that it is very difficult and not always necessary to completely eradicate the bad bugs. Understand also that there is no quick fix with beneficial insects. It is very difficult to maintain steady populations of good bugs, so often times several introductions are necessary.

 

Using beneficial insects to fight against harmful pests is an excellent part of any Integrated Pest Management plan. Not only will this process help control pests and improve yields, but it will also help inform you as the grower on an important part of your growing environment. The use of the good bugs will provide you with a safe and effective alternative to chemical applications. All of the beneficial insects in this article are available through Hummert International, and can be found at www.hummert.com. Perhaps the next time you are working in your garden and see something flying around your head you will take some time to consider: “is that a good bug or a bad bug?”

 

Sources

 

http://www.fao.org/ag/magazine/0512sp1.htm