Temperature and Insect Biology, Behavior, Monitoring and Control

August 2024 Edition: 

by: Curtis Meyers, A.C.E.

 

Introduction

Insects are poikilothermic, meaning they do not generate their own body heat, and the temperature of their environment is one of the primary environmental factors that affects their biology and behavior. Reproductive, locomotive, respiratory, and metabolic processes are all affected by temperature in a big way, meaning temperature affects where insects are, how many of them are there, how fast they are reproducing, and how long they live.

In this article, we will examine the importance of knowing how temperature is important when considering how to monitor, inspect for, and control insect pests. Please note this article will not dive too deeply into specific information about the effect of temperature on particular species of insects, but links to some helpful resources with that information will be available at the end of the article.

Temperature and Effective Monitoring and Inspections

It is important to understand how temperature affects a specific pest’s biology and behavior to effectively determine when and where to place insect monitors (traps).

For example, suppose you are monitoring for indianmeal moths with hanging pheromone traps, and the temperature is not warm enough for the adults to be actively flying. In this case, you will not be effectively monitoring this pest, as they are not able to access the hanging traps.

If you place monitors for crawling insects and conditions are too cold or hot, they may not move around in their environment enough to encounter the monitors.

Ensure you use monitoring devices and techniques that make sense for the temperature of the monitored area and the temperature range the target pest is active.

Inspections for insect activity generally focus on resources such as food, shelter, and moisture.

Don’t forget about temperature!

Many facilities and structures have multiple microenvironments with different temperatures that may be more favorable to insect activity. Spilled food in a freezer is not going to be at-risk of insect infestation while it remains in a freezer; there may be moisture and harborage available inside a boiler room but it may be too hot to support significant insect activity. Grain bins often have temperature differences within the grain mass and insects will be more active in areas with their ideal temperature range.

Focus insect inspections on areas that have resources and favorable temperatures!

Temperature and Control Treatments

Most pesticides require the pest to contact them, ingest them, or uptake them into their respiratory system to be effective.

If you are fumigating dormant insects that are respiring at a low rate, it will take more time and/or fumigant to kill your target pest.

 If insects are too cold or hot to move around in their environment, they may not encounter most pesticides applied as liquids, gels, fogs, or dusts.

Always ensure temperatures are favorable in treatment areas for effective control when choosing pesticide formulations and application areas to ensure efficacy.

Some pesticides have specific label instructions regarding temperatures. Remember to always read and follow pesticide label instructions to ensure effective treatments.

Temperature as a Control Tactic

Controlling temperature can be a tactic to reduce pest activity and reproduction rates, and even kill pests.

Cooling products, or areas of facilities, can force insects into quiescence (dormancy), which can delay product damage and spread of infestation in products or facilities until a more permanent solution can be found. Heating products or areas above an insect's ideal temperature can stop reproduction and force insects to move and seek out cooler areas.

Remember, insects will resume feeding and reproducing when temperatures return to their active range so ensure you have a long-term control plan in place before temperatures return to levels where insects will become active again.

Freezing and heating can both kill insect pests directly, as well.

Heating achieves control faster as insects generally tolerate lower temperatures longer than high ones

It is important to consider the effect of extreme temperatures on the product/facility/equipment to be temperature-treated. Extreme temperatures may affect product quality or damage equipment.

Treating a large amount of product, or large areas/facilities can also be challenging. Specialty equipment will likely be required and large, poorly insulated structures may not be able to be effectively temperature controlled.

For smaller amounts of palletized product, temperature-controlled trailers can be used to hold product at temperatures suited for treatment or control if it is impractical to heat or cool an entire structure.

Temperatures and times to control specific pest species, as well as descriptions of specialty equipment and best practices for using extreme temperatures to control insect pests can be found at the linked sites below.

Further Reading About Temperature’s Effect on Insect Biology

There are many online resources with a wealth of specific information about the effect of temperature on pest biology and control. I have included links to some of these resources below.

Insects Limited

https://www.insectslimited.com/blog/temperature-and-stored-product-pests

https://www.insectslimited.com/blog/when-it-comes-to-insects-temperature-over-everything

Quality Assurance Magazine

https://www.qualityassurancemag.com/article/managing-insects-with-temperature/

Extreme Temperatures: Paul Fields, Bhadriraju Subramanyam, Raj Hulasare

https://www.researchgate.net/publication/303249099_Extreme_temperatures