Arctic Insect Ecology

How arctic warming impacts insect wildlife-human interactions

Written by: Caroline Kim

Interview: Professor Lauren E. Culler

August 27, 2022

Thinking back to the post on Arctic Systems, we can recall that wildlife in the arctic have adapted in unique ways to survive the extreme climates. For example, plant life mostly consists of stubby shrubs: close to the ground to minimize energy expenditure, stay warm, and maximize nutrients. Likewise, arctic insects have significance to the ecological cycle as well as human interactions. Last week I had the opportunity to interview Professor Lauren Culler from the Environmental studies department at Dartmouth college, and I was able to gather some information on the arctic insects and some of her personal research experience.

Insects in the arctic differ, physically and behaviorally, from insects elsewhere in order to survive.

The two main factors that matter most are temper temperature (changes growth pattern and metabolisms), precipitation, soil moisture (mosquitoes/insects with aquatic life stages, precipitation/temperature is significant). Shrubification/change in habitat can cause preference for living areas. Just like anything in the arctic, there is a short and rapid growing season, leaving the reproduction window dormant most of the year. For example, mosquitos are around throughout June and July and the eggs are left frozen until the fall and spring. As a result, arctic insects grow faster in colder temperatures than insects in other areas. Without us/wildlife, mosquitoes have no food because mosquitos sometimes emerge earlier in the year or they emerge in higher numbers where there is more competition(in a more wet year). This idea of phenological change (change in timing of events) can cause several conflicts (mosquitoes change in emergence time). Caribou/reindeer are endothermic and have synced up reproduction cycles. However, the plants are ectothermic, so they respond in change to temperatures and grow earlier. This phenological mismatch (timing is off) makes it so that the nutrition from plants is past when animals such as Caribou have developed. Additionally, Caribou are known to change behavior according to insects. For example, they spend more time on top of windy ridges to avoid bugs, but this causes them to use up more energy and time. These ridges may also be places where there is less food for them, which further impacts the health and diets of the wildlife.

On the east side of Greenland, researchers in Denmark have measured insect abundance since the mid 1990’s. Certain groups have declined, others have been steady, and others have even increased. In Kangerlussuaq, two similar wolf spider species were researched, where one is in high numbers in wet areas and the other thrives in drier areas. In one of Professor Culler’s field studies, different colored buckets were filled with water, and mosquitos and data was collected on mosquitos to see how fast they grow. Insects were also grown at different temperatures in the lab, which allowed for predator-prey experiments. Insects in darker buckets grew faster and some resulted in dying from overheating (black ones heated up faster due to lower light reflectivity). (For more details on her research feel free to look into her articles).

In terms of human interaction, insects may be pests of agriculture, since there exists an interest in agriculture development in the arctic. Plus, tourism is not always pleasant with the mosquitoes, which might have economic relevance. Pollination is also important economically for its many benefits (not as important in arctic but important overall to sustain biodiversity). Insects are predators to other insects, which is important to maintaining an ecological balance. Humans destroying habitat/forests can change the temperature of the area, so conserving habitat in headwater streams can help. For example, in thermal refuge, fish swim upstream where it's colder. Overall, it is clear that one human interaction or change in temperature can set off a domino effect in arctic ecology, as is often the case in environmental sciences. However, with further research, testing, and creativity, a more permanent solution can be proposed.

Sources:

Special thanks to:

Lauren E. Culler, Ph.D.

Research Assistant Professor, Department of Environmental Studies

Senior Fellow for Climate & Environment, Institute of Arctic Studies

Dartmouth College

Hanover, New Hampshire