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Assessing changes in insect biomass and biodiversity at the Long Point World Biosphere Reserve (LPWBR)

Assessing changes in insect biomass and biodiversity at the Long Point World Biosphere Reserve (LPWBR)

by Summer Solmes

Summer Solmes

Dynamism of the biosphere is considered to be achieved by virtue of the most diverse and ecologically significant group of living organisms, insects. Crop and wildflower pollination, organic decomposition, biological control, and food provisioning, are among the many recognized services that insects provide, reflecting their global economic and ecological importance. Unfortunately, insects are also the most undervalued and underrepresented in conservation studies despite their rapid decline. Approximately 40% of all insect species are dramatically declining with the potential for triggering large-scale cascading effects across several ecological gradients. Climate change and habitat loss are among the few widely recognized drivers of this decline. A likely solution to this problem is the purposed conservation of insects in protected areas. Regarded for their long-term management of intact natural ecosystems and responsible stewardship, the earnest usage of protected areas may provide an antidote to the poison of anthropogenic infection. With the NSERC Undergraduate Student Research Award conferred to me earlier this year, I had the opportunity to conduct research under the supervision of EUC Associate Professor Sheila Colla, and Biology PhD Candidate Hadil Elsayed, on a biodiversity conservation project aiming to determine the gravity of anthropogenic threats to insect biomass and diversity in protected areas. My research takes at a place in the Long Point Biosphere Region, over a three-year period from 2021-2023, with the goal of informing conservation management on the matter of adapting to climate change.

Map of four sites sampled within the Long Point Biosphere Region. Three sites located in the National Wildlife Area (DJCS, ROSF, and WPWC) and one site located at St. Williams Conservation Reserve (MTA). DJCS – Dry Juniper Cottonwood Savannah; ROSF – Red Oak Sugar Maple Forest; WPWC – White Pine White Cedar; and MTA – Manestar Tract A.

The LPWBR is Ontario’s first Priority Place for conservation, situated in Norfolk County on the northern shore of Lake Erie, approximately 2.5 hours southwest of Toronto. It comprises a unique blend of sensitive habitats and watersheds, home to a wide array of flora and fauna, migratory birds, and species at risk. My study sites represent four ecologically different landscapes, three of which are located in the National Wildlife Area (NWA), and one in St. Williams Conservation Reserve (SWCR). The sites were selected as such to compare the potential effects of different management styles specific to those regions. The NWA is governed by Environment and Climate Change Canada’s Canadian Wildlife Service, whereby human access is restricted to researchers and management staff only, in contrast to the SWCR which is governed by the Ministry of Natural Resources and is open for public use.

Malaise traps are small tent-like structures intended to guide flying insects upwards along its seam, into a collecting container at the top.

Insects were sampled using Malaise traps during the months of May to August from 2021-2023 across the four different sites. Specimens were collected and preserved in a solution of 95% ethanol, sorted to the taxonomic level of Order, and subsequently dry-weighed. I used a multiple linear regression to calculate biomass statistics against several weather variables: number of frost days, minimum and maximum temperatures, and the total precipitation for each of the study months. With regards to calculating biodiversity statistics, I used the Shannon-Wiener Diversity Index to analyze bees, lady beetles and tiger beetles at each of the sites across 2021 and 2022. Bee diversity was analyzed at the level of Genus, and lady beetles and tiger beetles at the level of species.

Top to bottom: 1) Me confounded by my growing collection of bees! 2) Abdomen of a female Agapostemon bee (sweat bee) at 40x magnification. 3) Face of a Coelioxys, your common leaf-cutting cuckoo bee, displaying its beautiful mandibles at 40x magnification. 4) Back of the thorax and abdomen of a male Agapostemon (sweat bee). 5) A cute little six-spotted green tiger beetle, Cicindela sexguttata. 6) Harmonia axyridis, the infamous Multicoloured Asian lady beetle.

I chose to examine these specific insects based on their major contributions to ecosystem health. Bees are renowned pollinators providing several ecosystem services to humans as well as contributing to complex and interconnected ecologies. They support the growth of trees, flowers, and other plants which serve as food and shelter for other creatures of varying sizes.

Lady beetles and tiger beetles both provide crucial information about habitat quality, successional stages, and or disturbances. Lady beetles are beneficial herbivorous predators responsible for protecting crop and non-crop plants from ravages, and tiger beetles are excellent bioindicators of environmental health having very narrow habitat preferences. Additionally, I was interested in tracking the presence of the prolific alien species, Harmonia axyridis, a.k.a. the Multi-coloured Asian lady beetle, which poses predatory threats to native lady beetles and other beneficial insects.

An adult member of the suborder Nematocera, in the Chaoboridae family. Also known as the “Phantom midge.

Given the time constraint of the project, my results are preliminary as I lacked a complete dataset for the year 2023. The project was still in progress at the end of the USRA contract thus the months of July and August as a result had yet to be analyzed. Nonetheless, I produced three sets of results for biomass:

  1. Calculating insect biomass from 2021 to 2022 showed results of a general decline in total biomass with substantial decreases specific to Nematocera, a suborder of elongate, semi-aquatic flies. Drivers of this decline are positively correlated with variations in total precipitation.
  2. Calculating insect biomass across the months of May and June from 2021 to 2023 showed varied results dependent upon fluctuations in maximum temperature. As maximum temperature increased, so did biomass. Since I am only comparing two months across three years, this data provides new insights about the implications of INTRA-annual weather variations having drastic impacts on insect communities, in addition to the long-term effects of climate change. Minimum temperature and total precipitation were described as the secondary and tertiary correlated variables. 
  3. Calculating total biomass for Nematocera from 2021 to 2022 exhibited a loss of more than half its size from one year to the next. Total precipitation was the sole variable positively correlated with the change. This decline is noteworthy because Nematocera are an extremely vital group of insects responsible for maintaining intact food webs and include species that are bioindicators of ecosystem health and water quality. Many insectivorous birds are heavily reliant on members of Nematocera for their sustenance, and a decline in their biomass, even in the short-term, could forecast a long-term impact on these bird populations and the greater ecosystem itself.
Me putting species in the Order of Hymenoptera (ants, bees, wasps) and/or Lepidoptera (moths and butterflies) into a “kill jar” for collection and observation purposes. The kill jar contains ethyl acetate soaked into an absorbent plaster plate, commonly used in entomology as a killing agent useful for maintaing soft insect bodies, to allow for proper mounting in a collection.

Results of bee and beetle diversity varied by site although consensus indicated a general increase from 2021 to 2022. The data collected at ROSF was unsuitable for calculation as no lady beetles or tiger beetles were recorded, and only one Genus of bee was identified (Bombus). Variations in diversity trends across sites suggest an interplay between weather, habitat composition, and trap placement at each of the sites. More conclusive diversity results will benefit from additional data in subsequent years.

Next steps for this project include:

- Integrating 2023 data for the months of July and August
- Re-assessing changes in biomass and diversity across 2021-2023
- Determining correlated weather variables influencing change
- Integrating vegetation data and analyzing its influential relevance to change

This research is part of a larger project analyzing changes in insect biomass and biodiversity over a 30-year longitudinal period and is expected to make conclusions about how insect communities have changed in response to environmental stressors such as climate change and anthropogenic land-use.

Summer Solmes is an environmental management undergraduate student working alongside Associate Professor Sheila Colla and Biology PhD Candidate Hadil Elsayed to analyze short-term biological changes in insect communities in Ontario, Canada. Her research is focused on comparing inter-annual changes in total biomass, and biodiversity for important pollinators and bioindicators present in various habitats comprising the Long Point Biosphere Region. Her research sites are located in the National Wildlife Area and the St. Williams Conservation Reserve. She was a recipient of the NSERC Undergraduate Student Research Award (USRA) for which she assessed changes in insect communities at the Long Point World Biosphere Reserve to identify the impacts of anthropogenically produced environmental stressors in protected areas.