Integrated Pest Management

 From the VT State Beekeepers Meeting, Winter 2004

Resistance Management Integrated Pest Management

Anthony Jadczak, Maine State Apiarist

Vermont Beekeepers Association, January 27, 2004

Barre, Vermont

 

Definition:

 

Integrated Pest Management (IPM) is the selection, integration, and implementation of pest control based on predicted economic, ecological and sociological consequences.

 

IPM seeks maximum use of naturally occurring pest controls, including weather, disease agents, predators and parasites.  In addition, IPM utilizes various biological, physical and chemical control and habitat modification techniques.  Artificial controls are imposed only as required to keep a pest from surpassing intolerable population levels predetermined from accurate assessments of pest damage potential and the ecological, sociological, and economic costs of control measures. (Bottrell, Council on Environmental Quality 12/79)

 

From the British Columbia Pesticide Control Act (1997): Integrated Pest Management means a decision making process that uses a combination of techniques to suppress pests that must include but is not limited to the following elements: (a) planning and managing ecosystems to prevent organisms from becoming pests; (b) identifying potential pest problems; (c) monitoring populations of pests and beneficial organisms, pest damage, and environmental conditions; (d) using injury thresholds in making treatment decisions; (e) reducing pest populations to acceptable levels using strategies that may include a combination of biological, physical, cultural, mechanical, behavioral, and chemical controls; (f) evaluating the effectiveness of treatments.

 

Principles:

1. Potentially harmful species will continue to exist at tolerable levels of abundance. Manage vs. eradicate.

2. The ecosystem is the management unit.  The ecosystem is manipulated in order to hold pests at tolerable levels while avoiding disruptions of the ecosystem.

3. Use of natural controls is maximized (parasites, predators, weather)

4. Any control procedure may produce unexpected and undesirable consequences.

5. An interdisciplinary systems approach is essential.  Effective IPM is an integral part of overall management of farms, forests, etc.

Guidelines:

1. Analyze the pest status of each of the reportedly injurious organisms and establish economic thresholds for the real pests.

2. Devise schemes for lowering equilibrium positions of key pests by:

 Deliberate introduction of natural parasites, predators, diseases;

 Use of pest resistant or pest free stocks;

 Modification of pest environment to increase effectiveness of the pests biological control agents to destroy its breeding, feeding or shelter habitat.

3. During emergency situations seek remedial measures that cause minimal ecological disruption.

4. Devise monitoring techniques.

 

Control Techniques:

 

1. Biological Control parasites, predators, pathogens

2. Host Resistance

3. Cultural Control

4. Physical /Mechanical Control

5. Chemical Pesticides

6. Miscellaneous Techniques-attractants, pheromones, growth regulators, autocidal control

 

IPM Strategies for Tracheal Mite Control

 

Honey Bee Tracheal Mite ( Acarapis woodi)- The honey bee tracheal mite was first documented in the US in 1984.  Following the initial discovery, the mite rapidly spread throughout the continent and was responsible for massive honey bee die offs for about ten years.  The negative impact from tracheal mites was most severe in northern states.  At present, many of the surviving honey bee stocks in the US have various degrees of tracheal mite resistance.

Economic Threshold: Survey /detection methods for tracheal mites involve the collection of adult honey bees at the colony level or apiary level (composite sample).  The prothoracic trachea are then examined microscopically.  For an individual hive survey the sample size should be 33-50 bees.  Composite samples require the examination of 100 bees in the apiary.  Composite samples should consist of approximately 10+ bees /hive in the apiary.  An alternative composite sampling method consists of examination of 100 bees taken from 10% of the hives within the apiary (50-100 bees/hive

 There is significant winter mortality for colonies with infestations >30%

 The infestation level in autumn is correlated with the previous seasons weather conditions and honey production. Favorable weather conditions and high honey production usually result in lower tracheal mite infestation at seasons end

Control Techniques:

 Host Resistance- Resistant honey bee stocks are currently available.  The Buckfast strain and Carniolan race of honey bee express resistance to tracheal mites.  In addition, survivorstocks of bees also express tracheal mite resistance.

 Cultural control- Splitting or making multiple nuclei from hives with moderate infestations of tracheal mite effectively reduces the mite infestation.

 Chemical control- Menthol crystals applied in the spring and fall according to label directions kill tracheal mites.  Formic acid (Apicure) applied in the spring and fall (if necessary) kill tracheal mites.  Vegetable oil patties continuously applied in the brood nest reduce tracheal mite infestations.

IPM Strategies for Varroa

 

Varroa mite (Varroa destructor) The Varroa mite formerly known as Varroa  jacobsoni, was first documented in the US in 1987 and has since been identified on all of the continents that bees inhabit. Unlike the tracheal mite, Varroa is visible without magnification.   The female mite is 1mm long and 1.5mm wide, reddish brown and flat.  Varroa feed upon the haemolymph of the adult and immature stages of the bee and reproduce within the brood.

 

Due to importation of the European honey bee, Apis mellifera during the late 1800s into Southeast Asia, the Varroa mite has had an opportunity to adapt to A. mellifera from its original host, the Eastern honey bee (Apis cerana).   European honey bee colonies infested with Varroa exhibit a progressive weakening due to the mites feeding behavior and from virus and bacteria vectored by the mite.  At present, without corrective action, 100 percent of hives within an apiary may die within 3 years.

 

Sampling Techniques: Varroa mites can be found on adult bees, within the capped brood and in hive debris on the bottom board.  Since the mite has a preference for drone brood, it is more readily found on drone pupae at low level infestations.  See handout: Varroa Detection Techniques.

 

Economic Thresholds: During the past 20+ years, honey bee researchers have tried to determine effective sampling techniques, economic thresholds and action or treatment thresholds for effective Varroa management in bee culture.  Following are some of the research finds:

--Nikolskii, 1980, USSR- Sample consisting of 100 adult bees.  Three categories of infestation: 1-10 mites=low; 11-20=moderate; 20+=heavy.  For colonies killed in the Primorski region mite counts ranged 21-208.  For colonies that survived counts were 4-19 mites/100 bees.  The author suggests that hives with 15-20 mites in August/September will die in late fall or winter without corrective action.

 

--Poltev, 1981, Moscow- Sample 50-100 bees in the summer (1%lye wash).  If 20 mites/100 bees the hive will decline; 50 mites/100bees the hive will probably die.

--Hood & Delaplane, 1998 Georgia, USA- suggest late season treatment when mite Populations reach 3,172-4,261/ hive. (15-38 mites in 300 bee ether roll or 59- 187 mites found on overnight sticky board- natural drop)

 

Delaplane suggests that if hives were treated at the above thresholds in August (15 mites/300 bees or 117 mites overnight on sticky board) the hives will recover.  If treatment was delayed until October then the hives did not recover.  He concluded that spring samples (February in GA) of 2 mites via ether roll and 4 mites on a sticky board, indicates a Varroa population of 70 mites in the hive  In addition an ether roll of 14 and sticky board count of 187 in August means the hive has a mite population of 4261.

 

--Caron, 2002, EAS Cornell Univ- Recommends a natural Varroa drop survey using a bottom board detector over a 3 day period in August.  Count the mites and divide by 3.

 

He suggests that < 50 mites/day- no need to treat; 50-100 mites/day-medium risk ? treat;  100-600 mites/day- high risk, treat.  For the sugar roll technique in mid August, Caron suggests a sample size or 300 bees, 1 tablespoon of powdered sugar, shake for 90 seconds.  His research indicates that 75% of the mites will be recovered.  If <12 mites-no treat; 12-15 mites medium risk-?? treat; >15 mites- high risk- treat.  For the drone brood survey Caron suggests a sample size of 100 drones: < 5 mites- no treat; 5-10 medium risk, ??treat; > 10 mites treat.  Caron does not recommend ether roll since he does not consider it as sensitive as the sugar roll.  Jadczaks experience in Maine differs somewhat.  Mite surveys conducted in Maine during cool weather with limited brood showed greater sensitivity via ether roll vs sugar roll (false negative samples).

 

Mussen, 1993, Univ CA- assumes the hive has brood present and there are 30,000 bees in the hive.  He says: # mites on board x 5 = mites in the hive and # mites ether roll x 500 =number of mites in the hive. < 100 mites in summer- wait until fall (Sept/Oct) to treat; 100-1000 mites treat after honey removal; > 1000 mites remove supers, treat and treat again in October.

 

1989 Cooperative Agreement Concerning Varroa Mite for Interstate Certification- developed by ME, FL, NY, NH, PA, ND established action thresholds for Varroa treatment. 5% inspection of hives post treatment via ether roll.  If an average of >2 mites/ether roll is found, investigate reason for treatment failure and possibly require re-treatment.  At or near 6 months post treatment, survey about 10% of the colonies via ether roll.  If an average of 20 mites/sample is found treatment is required before shipment south.

 

Control Techniques:

 

Host Resistance- Stocks of honey bees have been released to queen breeders from the USDA Bee Lab, Baton Rouge, LA. The Russian stock originated from the Primorski region of Russia and is considered a Carniolan race of honey bee.  Varroa populations build at about 1/3 the rate on these bees compared to normal US bee stocks.  The SMR(suppressed mite reproduction) stock also know as the Harbo line was developed by John Harbo, USDA, Baton Rouge. Honey bee populations of this line have demonstrated a lower rate of Varroa population growth.  The exact mechanism for the resistance isn’t fully understood but is thought to be related to where the female Varroa lays the fecal patch prior to laying eggs.  Varroa infesting SMR brood, defecate on the honey bee pupa instead of the cell wall which is thought to interfere with mite reproduction.

 

Cultural Control-

 

Drone brood removal -management has been investigated by Grobov, 1977 in Russian apiaries.  He states that 20-30% of the Varroa can be removed in spring via this method. This cultural control doesn’t reduce mite populations enough to eliminate fall treatment.

 

Trapping Comb method- Maul, 1983, Germany developed a method to concentrate worker brood on a limited number of frames that are then removed.  The trapping combs are placed between 2 queen excluders and the queen is kept on one or more combs for 7-9 days.  She is then moved to the next empty comb, etc. and the brood is removed as soon as it is capped.  Maul claimed 96% efficacy if 4 combs were used and 93.5% efficacy when 3 combs were used.

 

Buchler method-is a modification of the Maul trapping comb method using drone comb

 

In the Netherlands (1984) it was reported that brood removal and destruction during the month of May was very effective in reducing mite populations since approximately 90% of the Varroa are in the brood at that time of year

 

The above systems are labor intensive and a strict schedule must be followed for success

 

Physical/Mechanical Control-

 

Screened bottom boards are reported to reduce the mite level by about 10%.  This level of control is not sufficient enough to eliminate fall treatment.  The screened bottom board operated with a sticky boardis an effective means to evaluate mite populations.  Investigations have been undertaken using screened bottom boards in conjunction with a Varroa irritant such as tobacco smoke (Russia, Netherlands) or powders such as talc, flour, powdered sugar and sucrose octanoate esters (40%) which is made from sugar and vegetable oil derived fatty acids.

 

Chemical Pesticides- Beekeepers in the North America and parts of Europe primarily rely on the control of Varroa.  The list of chemical controls used to combat Varroa is extensive and many of these are no longer used.  Problems associated with residues in wax and honey or mite resistance to these compounds has resulted in discontinued use and the search for new materials.  The current trend in Europe and to a lesser degree in North America is to investigate essential oils such as thymol, menthol and other terpenes. In addition, the use of organic acids such as formic, oxalic and lactic acid are effective Varroa treatments.  On May 23, 2003 , the US-EPA granted the Maine Department of Agriculture a Section 18 Emergency Exemption for ApiLifeVar which is a thymol based Varroa control produced in Italy. A number of states have also submitted petitions to the EPA for this product.

 

Bio-control

 

Fungal pathogens Scientists are investigating Varroa control via introducing fungal pathogens of the mite into honey bee colonies by various delivery methods

 

Miscellaneous- Presently, the USDA Bee Lab, Tucson, AZ is investigating a pheromone for Varroa control/suppression.  Last fall, the Maine Department of Agriculture and others cooperated with the USDA by evaluating a pheromone produced by honey bees under a variety of weather conditions.

 

 

 

Used with Tony Jadczak permission.