by Wm. Michael Hood
Dept. of Entomology, Soils, and Plant Sciences
Clemson, South Carolina
Integrated Pest Management, or simply IPM for short, is a phrase that is familiar to many beekeepers today. This concept of pest management seeks to control pests using a variety of strategies that are safe, effective and economical and will lead to a sustainable level of control. The concept and application of IPM should be covered in all beekeeping short courses that include pest management. My colleague and good friend Nicholas Calderone at Cornell University states this well when he said, “a discussion of IPM is important at anytime because it always represents the best long-term approach to the problem of pest management (2). “
According to a 2008 University of Massachusetts report (4), IPM “is a long-standing, science based, decision-making process that identifies and reduces risks from pests and pest-management-related strategies. It coordinates the use of pest biology, environmental information and available technology to prevent unacceptable levels of pest damage by the most economical means, while posing the least possible risk to people, property, resources and the environment. IPM provides an effective strategy for managing pests in all arenas from developed agricultural, residential, and public areas to wild lands. IPM serves as an umbrella to provide an effective, all encompassing, low risk approach to protect resources and people from pests. (IPM Roadmap, USDA, 2004)”.
For a little history of IPM, we need to go back to the period in time just after WWII when many synthetic insecticides were introduced in the United States (3). Growers welcomed the addition of these knew pest control products which were very effective at dropping the pest density quickly to a manageable level. However, entomologists soon noticed that these mostly calendar-based insecticide spray programs also killed off the natural predators of these pests which allowed a quick resurgence of the target-pest requiring additional applications. These repeated applications sometimes killed off many beneficial pollinators too, such as bumble bees and honey bees. In California and in some of the cotton-belt states such as Arkansas, entomologists soon began a new concept of pest management called “supervised pest control” which sought to reduce the number of pesticide applications based upon a monitoring system that estimated the number of target insects in the field and the natural enemy populations (3).
By the 1950s, California entomologists coined the term “integrated control” which sought to identify the best mix of chemical and biological control for many major pests (3). The goal of this new program was to use chemical insecticides in a manner which resulted in minimum effects on the biological control complex. By regular monitoring, the grower treated only when a population level reached the economic threshold to prevent the pest population from reaching the economic injury level, which is the point at which the economic losses of the crop would exceed the cost of the control. Treating only when the pest population reached an economic threshold, offered the grower other benefits such as reduced number of pesticide applications which saved money by reducing the cost of pesticides and reduced the number of trips through the field to apply the treatment. Longer periods between treatments also extended the useful life of a given pesticide or family of pesticides having the same mode of action by slowing resistance.
Later on, the phrase “integrated pest management” was introduced which expanded the concept of integrated control to include all classes of pests and to include other control measures in addition to chemical and biological controls (3). Genetic, cultural, mechanical, and physical tactics were added to the IPM arsenal. In 1972, President Richard Nixon directed federal agencies to promote the concept and application of IPM to all relevant sectors. This expanded approach to pest management included the cooperation of entomologists, nematologists, plant pathologists, and weed scientists (3). Much of the applied research that makes up the core of the IPM programs has been developed since the 1970s at land-grant colleges and universities in the US, and their counterparts from other parts of the world (5).
Although IPM’s early focus was on agricultural field pest management, it now includes diseases, weeds, and other pests that infest homes, commercial buildings, landscapes, and animals. Schools, golf courses, dairies, and poultry operations are just a few examples of areas which use IPM today.
The IPM concept used by many growers was certainly a step in the right direction for the beekeeping industry because it resulted in less use of pesticides in the field. However, even after this program was instituted, there were times when circumstances lead to massive areas being sprayed with pesticides such as the boll weevil eradication program that began in the Southern US during the 1970s (1). Some beekeeping operations were hammered by pesticides and beekeepers became reluctant to place their colonies near cotton, which by the way produces a beautiful crop of honey some years. Another example of massive pesticide sprays occurred following hurricane “Hugo”, a category 5 hurricane, which struck the eastern coast of North and South Carolina in September 1989. Aerial mosquito abatement programs were mobilized which required large areas to be sprayed even during daylight hours which had a detrimental affect on the feral as well as managed colonies of honey bees and other pollinators in the region.
Up until this time in history, IPM was a term foreign to most US beekeepers. However, this changed during the 1980s and 1990s when the term IPM became a familiar topic listed on many beekeeping meeting programs. Varroa mite management issues became more complex when chemical control failure became widespread. Enter such terms to the modern beekeeping vocabulary as pest surveys, treatment thresholds, chemical rotation, ether roll, varroa detector boards, and bottom board screens. Most beekeepers today practice varying levels of IPM in their beekeeping operations. For a full comprehensive understanding of IPM, let’s take a serious look at some principles of modern day integrated pest management.
Beekeeping IPM Principles
There are eight basic principles of a beekeeping IPM program:
- Acceptable pest levels: The emphasis here is on pest control rather than on pest eradication, because complete elimination of a pest is sometimes impractical and often impossible. A pest eradication program is often too costly and environmentally prohibitive. However, a good example of an eradication program is the USDA Boll Weevil Eradication Program (1) mentioned above. This program has been ongoing since fall, 1978 and it continues to be a costly program. The program is based upon a clear understanding of the vulnerable biology of the weevil, the high-chance of success of the program, and support/cost-sharing of the program with cotton growers. As for the US beekeeping industry, a recent pest to enter the US is the small hive beetle which was first collected in South Carolina in 1996, but was not properly identified till July 1998 from beetle collections in Florida. Following this first identification, surveys were soon conducted in the Southeastern US for small hive beetles and reports indicated that the pest was found to be wide spread in the coastal areas of four SE states. Not only was the pest found in managed colonies, but they were also found in feral colonies as well. Once a beekeeping pest is established in the wild, any efforts at eradication is a real challenge and very costly. Apparently, eradication efforts for small hive beetles in the US were not seriously considered. As with other beekeeping pests such as the tracheal and varroa mites that have been discovered in the US in the past 25 years, eradication efforts were not practical because of widespread occurrence of these pests and a biological control system was neither available nor practical. Therefore, the US beekeeping industry has set out to establish “acceptable pest levels” using treatment thresholds or action thresholds which can be defined as the pest population level at which significant control is necessary to prevent the pest population from reaching the economic injury level. For the beekeeping industry, the economic injury level is the pest population level that colony collapse is expected, regardless of control efforts. These thresholds are pest, site, and time specific and must be re-developed or confirmed in regions outside the region for which they were developed. Using a research-based treatment threshold system will eliminate many unnecessary treatments, thus slowing down resistance of a pest to a specific plant-derived or synthetic chemical. If too high a percentage of the pest population is repeatedly eliminated by a chemical, the process will leave behind the resistant part of the population which will reproduce forming a resistant population (3). By not killing off all the susceptible individuals of a population by a chemical, there will be left behind un-resistant individuals that will dilute any resistant genes in a pest population.
- Preventive cultural and regulatory practices. The national “Honey Bee Act” of 1922 was passed by Congress and signed into law by the President in 1922 (9). The Act was mainly a result of an effort to protect our honey bees from the Isle of Wight disease that had occurred in other parts of the world. This legislation restricted the importation of live adult honey bees into the US and has played a major role in reducing the chance of honey bee pests and diseases from entering the country. The Honey Bee Act of 1922 has been amended three times since its passage, 1947, 1962, and 1976 (9). Prior to passage of this federal legislation, unsuccessful attempts were made to import other honey bee species into the US, such as Apis dorsata, the giant honey bee. The American beekeeper Frank Benton attempted in 1881 to import colonies of the giant honey bee from Java, Ceylon, and Singapore (10). We now know that the giant honey bee was unsuitable for the US and importation of this species may have brought along with it some unwanted diseases and pests. Some state bee laws have been passed that disallow the management of colonies contaminated with American foulbrood and burning is required. A cultural change has taken place in the Southeastern US where small hive beetles are a problem. Most beginner level short courses in the past have taught beekeepers to place their colonies in apiary locations that receive morning sun and afternoon shade. However, beekeepers are now advised to locate their apiaries in full sun rather than shade to reduce small hive beetle reproduction.
- Monitoring or scouting practices. A good understanding of the biology and behavior of a pest, along with early detection will normally offer the beekeeper time to use non-chemical options. Most pests have a seasonal life cycle which is predictable and therefore a monitoring program can be more focused at certain times of the year. Since insects and mites are cold-blooded, their development is temperature-controlled and development cycles have been recorded based upon accumulated degree-days. In most cases concerning honey bees and their pests, they live in mostly a temperature-controlled environment, so development time is easier to predict. The one exception is wax moths that are a major problem in stored drawn comb which is normally stored away from the warm environment inside a beehive. The wax moth’s life cycle slows drastically in the wintertime, so a degree day model is possible. Varroa mites are a good example of a honey bee pest which monitoring is essential for effective control, especially during some parts of the season. Reliable survey techniques that have been rigorously tested are always needed in an effective IPM program. Varroa mite detector boards, ether role, and alcohol wash are tools used to monitor or survey for this pest. Varroa mite treatment thresholds have been developed in some regions of the US and regular estimation of the varroa population to discover damaging pest levels is highly recommended.
- Genetic control. Genetic practices include the release of sterile or incompatible individuals with the intention of flooding the population with inferior stock. The Screwworm Eradication Program beginning in the 1930s proved to be one of the “greatest success stories in the history of American Agriculture (7).” The screwworm was a major, widespread insect pest that fed on living tissues of warm bloodied domestic and wild animals in the US, Mexico, and most of Central America. USDA scientists developed a sterile male release strategy that provided screwworm eradication using little or no pesticides (7). In beekeeping, the development or selection of pest resistant stock is a good example of genetic control which is relative to beekeeping today. The Russian Honey Bee Breeding Program, lead by USDA/ARS bee scientist Thomas Rinderer, was begun in 1997 when queens were imported into the US from Russia. Colonies headed up by Russian queens show resistance to varroa mites as well as some tolerance to small hive beetles. Varroa sensitive hygienic (VSH) bees have been selected from present US honey bee stocks and they also show a tolerance or resistance to varroa mites. This program was initiated and maintained for several years by now retired USDA/ARS bee scientist John Harbo. Jeff Harris now heads up the VSH program at the USDA/ARS Honey Bee Genetics and Physiology Lab in Baton Rouge, La. Queens from both programs are now available for purchase in the US.
- Mechanical control. In the beekeeping industry, many mechanical control tools are used to maintain pest populations below a treatment threshold. More drastic measures, such as chemical control, are recommended when the pest population reaches the treatment threshold level. However, mechanical control is highly recommended for honey bee pests, such the small hive beetle. Hand smashing, vacuuming, and trapping are examples of recommended control measures for this pest. The use of screened bottom boards is recommended for varroa mite control which allows the varroa to fall to the ground and not recover. Cutting or removal of drawn brood from a colony is a form of mechanical control for varroa mites because varroa are naturally attracted to drawn brood over worker brood.
- Physical control. Physical practices include the use of heat, cold, light, humidity, carbon dioxide, light, ventilation or sound to control a pest. Most pests have physical limitations that affect their activities or survival. Freezing temperatures are an excellent way of killing or controlling wax moths and small hive beetles in stored drawn comb. Light and ventilation are also recommended for control of wax moths in stored drawn comb. Heat has been shown to affect varroa survival and placement of colonies in sun may aid in control of this pest. Placement of colonies in sun will also create drier soil conditions which disrupt the lifecycle of small hive beetles.
- Biological control. Natural biological processes or materials such as beneficial insects or various pathogens offer safe and sometimes economical methods of pest control. A Bacillus thurengensis (BT) product, Certan®, was once registered for wax moth control in stored comb but the registration of this product has been withdrawn and is no longer available in the US. Soil nematodes, Heterorhabditis indica, are currently marketed in the US (Southeastern Insectaries, Inc., Perry, Georgia, ph. 1-877-967-6777) for small hive beetle control as a soil treatment to kill beetles when they enter the soil to pupate. The imported fire ant, Solenopsis invicta, an insect predator may also assist in controlling wax moths in stored comb and small hive beetles as they enter the soil. The braconid wasp, Apanteles galleriae, is a parasitoid of wax moth larvae in the Southern US, but low parasitism rates have been reported in natural infestations (8).
- Chemical control. Synthetic pesticides played a major role in the management of honey bee pests like varroa mites following their first discovery in the US. Most beekeepers quickly jumped on the pesticide treadmill beginning in the late 1980s and many simply wanted to know when to place the pesticides in the hive and when to remove them, a similar move (calendar based approach) adopted by the agricultural industry following WWII. Some beekeepers elected to illegally use products not labeled for beekeeping pests, such as varroa. Within a few years of repeated use, some beekeepers began to report that products like Apistan ®and Checkmite +® were no longer effective for varroa mite control. If these products had been used by beekeepers in an IPM approach and only when necessary requiring longer periods of time between treatments, the useful life of these synthetic chemicals would likely have been prolonged. Other chemicals such as organic acids (formic acid) and plant derived chemicals or essential oils (thymol) are available to beekeepers in their pest management strategies today. A similar fate has now developed in many states where American foulbrood is resistant to the antibiotic, Terramycin. Overuse of a single antibiotic for several years likely played a major role in this problem, also. Pheromones, attractants, and repellants are other chemicals that play a role in beekeeping pest management. An old standby chemical Para dichlorobenzene (PDB) is a chemical that is used in stored comb to repel wax moths. Small hive beetles are known to be attracted to the honey bee alarm pheromone and a yeast- based material produced by beetle larvae. These newer type chemicals will likely play a major role in beekeeping pest management in the future.
The US beekeeping industry must continue to promote and use the IPM concept to survive in these uncertain economic times. According to Jacob (2009), “the pervasive and rampant problems of acaricide resistant mites, Terramycin resistant foulbrood, and contaminated honey threaten modern apiculture’s economic viability and clean wholesome image.” IPM can help the beekeeper achieve pest management goals by minimizing the use of chemicals in the short run and extending the useful life of specific chemicals in the long run (2). Many IPM tools are inexpensive and used in combination with other strategies offer the beekeeping industry pest management solutions which are more sustainable. The IPM program practiced by commercial beekeepers will be different from the program used by the part-time beekeepers, so no set strategy will be used by the industry. Beekeepers will have to be on the lookout for new pest management options which reduce costs, help maintain acceptable pest levels, and ensure all hive products are safe for the consumer. Under the IPM concept, the US beekeeper will now have to be more patient than in the past and learn to be more content with allowing a pest to survive at low population levels.
Advantages and Disadvantages of Beekeeping IPM
- More sustainable
- Decreased use of chemicals in the hive
- Extends the useful life of chemicals used by lengthening time between applications
- More economical in long run
- Less chance of hive product contamination
- Less exposure by beekeeper to chemicals
- Additional time and commitment required to implement
- Often requires multiple strategies
- Evaluation required
Unsustainable honey bee colony losses in recent years have been extremely costly to the US beekeeping industry. Beekeepers are now faced with many unforeseen challenges that have been identified or discovered as a result of a broad-based research net that has been cast to solve the much publicized colony collapse disorder (CCD). Regardless of the outcome of the CCD dilemma, the US beekeeping industry must utilize an integrated pest management approach to survive. This means that beekeepers will no longer have the luxury of using a single pesticide or a single antibiotic to control their colony problem, as in the past. An arsenal of strategies is now available to maintain healthy colonies including genetic, biological, cultural, mechanical, physical, and chemical control. Beekeepers must be better informed than ever to select the best combination of IPM tools for their beekeeping operation. Beekeepers must be capable of evaluating and modifying their IPM strategies to survive and succeed in the future. Asking the right questions is important (3). Were my strategies successful this year? Was the pest or disease prevented or managed to my satisfaction? Did the pest population exceed the treatment threshold level? Were there any unintended side effects as a result of my actions? And lastly, what must I do in the future to improve my pest management plan? Today’s beekeepers must be vigilant in their pest management plans to stay one step ahead of their pest problems.
- Boll weevil Eradication Program, National Cotton Council of America. http://www.cotton.org/tech/pest/bollweevil/index.cfm
- Calderone, N. 1999. An introduction to integrated pest management for honey bee pests. The Bee-Files. Dyce Laboratory for Honey Bee Studies, Cornell University. Pp. 5.
- Integrated Pest Management. 2009. Wikipedia, the free encyclopedia. Pp. 6. http://en.wikipedia.org/wiki/Integrated_pest_management.
- Integrated Pest Management – Generic IPM Plan Tool. 2008. University of Massachusetts Amherst Extension. Pp. 8. http://www.umass.edu/umext/ipm/publications/guidelines/ipm_plan_tool.html
- Integrated Pest Management. 2009. Administration / Coordination. University of Massachusetts Amherst Extension. Pp. 2. http://www.umass.edu/umext/ipm/projects/administration.html
- Jacob, J. Integrate Your Pest Management. Old Sol Enterprises.
- Screwworm Eradication Program Records: NAL Collections, National Agricultural Library.
- Shimamori, K. 1987. On the biology of Apanteles galleriae, a parasite of the two species of moths. Honeybee Science 88: 107-112.
- Shimanuki, H. and P. Lima. The Federal Honey Bee Act and Amendments. In Honey Bee Pests, Predators, & Diseases. Editors R. Morse and K. Flottum, Published by the A.I. Root Co., Medina, Ohio. P. 557.
- Strange, J. 2001. “A Severe stinging and much fatigue” – Frank Benton and his 1881 search for Apis dorsata. American Entomologist, Vol. 47, No. 2: 112-116.