Solutions – Insect Growth Regulators for Collections

Insect Growth Regulators / Collections

What are Insect Growth Regulators (IGR’s)?

Insect Growth Regulators (IGR’s) are synthetic pesticides that mimic certain insect hormones, preventing those insects from growing to egg-laying adults and reproducing. An IGR halts, slows, or disrupts an insect’s maturation from egg to adult with the specific objective of reducing or eliminating the insect’s reproductive capability. Control of target pests is achieved over time as sterile adults die off without being able to produce a new generation.Depending on the pest, IGRs may be applied alone or in combination with a toxin.

When properly applied, Insect Growth Regulators (IGR’s) can be a useful component in an IPM program to control some cultural heritage pests. Note however that IGRs have limited use in collecting institutions: they  are only effective for certain pests and cannot be used as a substitute for good housekeeping. IGR’s should be used as part of a comprehensive prevention and treatment program that also involves reduction of adult population through least-invasive means and prevention of infestation through structural, sanitation, and cultural modifications.

Can collections be treated with IGRs?

Cultural materials should NEVER be treated with direct IGR treatment by space fogging or spraying. Direct application of an IGR may unalterably change the chemical makeup of an object or artifact. Although IGRs themselves have a low toxicity for humans, other factors make them a solution in limited situations only.

Pest management professionals may propose to use an IGR  in a facility, applied as a topical spray or as a fog. Fogging should never be used in a collecting institution. Fogging should not be used directly on collections or in spaces where collections are not enclosed and well-sealed. IGR’s may be considered for large scale building infestations which cannot be resolved by standard recommended IPM solutions such as high or low temperature and anoxia. For such large scale infestations, IGR’s may be considered for treating floors, cracks and crevices.  After treatment, the target pest may still be alive for a period of time.

One of the characteristics exhibited in insects affected by an IGR is the potential for an abnormally prolonged larval state. Larval stages in each of these insects are the primary source of damage to the infested object material. Prolonging the larval stage without the use of low temperature, heat, or anoxia, treatment to kill the existing population would be counterproductive. IGR’s should never be used as a sole means of control in artifacts infested with dermestids, clothes moths, or stored product pests.

General Treatment of Building Floors, Cracks and Crevices

If after careful consideration the collecting institution decides to consult with and hire a licensed pest management contractor to use an IGR in the building, the contractor should supply institution staff with an EPA-approved label and Safety Data Sheet (SDS, formerly known as Material Safety Data Sheet or MSDS) for the IGR and any pesticides used in conjunction. Labels, SDS and application records should be retained according to building safety procedures in an easily accessible place for future reference. A detailed written plan of application should be offered by the pest management professional to museum management to insure collections are not exposed to pesticides. A staff member should accompany the professional on each visit. The use of any chemical treatment in a building should be documented. All records related to the history of infestation and eradication procedures should be accessible. The IPM policy statements on this site give examples of ways museums carry out documentation.

There are many IGR products available for use in museums and historic houses. Most can be categorized into one of two groups: juvenile and chitin. Please see Solutions-Insect Growth Regulators (IGRs) for Subterranean Termites for further information on IGR’s.

IGR’s for as a crack and crevice treatment in collection storage areas

Treatment of collections storage space with a liquid IGR can be can be an effective means of dealing with stubborn infestations, especially when used in conjunction with appropriately labeled adulticides. In some situations, satisfactory control of target pests can be achieved when using the IGR as a stand-alone product. This is accomplished in one of two ways:

  1. Introduction of the IGR as a crack/crevice, spot, or void treatment. Oftentimes, dermestids, silverfish, and other museum pest infestations originate in wall voids, perhaps at the site of an old stinging-insect nest or a bird, rodent, or other small animal carcass. In the case of historic houses, silverfish my feed on edible insulation materials in the wall void, creating a very difficult situation to resolve. When extraction of the feeding material from the wall void is not feasible, the unique movement and infiltration of the IGR molecules inside of a given space can provide a measure of control not possible with most adulticides. Since the IGR does not need to physically touch an insect to be effective, widespread hormone disruption could lead to population reduction.
  2. Introduction of the IGR as a spot treatment of infested carpet or other fabric used to cushion collection storage carts, infested carpet adjacent to collections storage, or other areas that are suspected to be a harborage for eggs and early instar larval specimens of a museum pest species. In this instance, the entire surface of the area in question is treated. Again, this can be accomplished with the aid of an appropriately labeled adulticide or by using the growth regulator as a stand-alone method of treatment. The severity of infestation coupled with the dynamics of the treatment area will dictate which method is appropriate.
  3. When planning a liquid IGR treatment, consideration should be given to the material being treated, such as a wall/floor junction. Many IGR’s are emulsions, and staining or slight odor residues may occur on raw concrete or unvarnished wood if overspray occurs. A spot test of a small, inconspicuous area of the material in question should clear up many uncertainties.

Created 2015, Updated 2018

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