Title

The Effects of Temperature and a Common Herbicide on Egg-Laying in the Variable Field Cricket, Gryllus lineaticeps

Lead Author Major

Cindy Vo

Lead Author Status

Junior

Format

Oral Presentation

Faculty Mentor Name

Zachary Stahlschmidt

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Glyphosate (GLY) is the active ingredient in the most commonly used herbicides in agriculture today. Although GLY-based herbicides (GBHs) target plants and other microorganisms, they may contaminate the surrounding environment and negatively affect non-target species (e.g., animals). In addition to GLY and GBH, animals are exposed to increasingly warm temperatures associated with climate change. However, the combined effects of GLY/GBH and temperature on terrestrial animals are unknown. Therefore, we investigated the effects of GLY and a GBH (Roundup®️ Weed & Grass Killer Super Concentrate; 5 mg acid equivalent GLY L-1) on the reproductive behavior (oviposition or egg-laying) of the variable field cricket, Gryllus lineaticeps under five different temperatures (20, 24, 28, 32, and 36℃). Females chose to lay more eggs in substrate containing GBH at 32℃, and they increased egg-laying when multiple oviposition sites were available. Oviposition specialization increased at temperature extremes, suggesting temperature may modulate the tradeoff between maternal and offspring fitness because clumping eggs into a small number of sites reduces females’ predation risk while potentially reducing offspring fitness. There was a thermal mismatch between oviposition and offspring survival because the optimal temperature for oviposition was approximately 27-32℃, which is significantly warmer than the optimal temperature for egg survival (25℃). We are the first to examine interactions between temperature and GLY/GBH in a terrestrial animal and on oviposition in any animal. Our results suggest that temperature and the availability of oviposition sites may be more important than GLY or GBH when making egg-laying decisions.

Location

University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211

Start Date

24-4-2021 2:30 PM

End Date

24-4-2021 2:45 PM

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Apr 24th, 2:30 PM Apr 24th, 2:45 PM

The Effects of Temperature and a Common Herbicide on Egg-Laying in the Variable Field Cricket, Gryllus lineaticeps

University of the Pacific, 3601 Pacific Ave., Stockton, CA 95211

Glyphosate (GLY) is the active ingredient in the most commonly used herbicides in agriculture today. Although GLY-based herbicides (GBHs) target plants and other microorganisms, they may contaminate the surrounding environment and negatively affect non-target species (e.g., animals). In addition to GLY and GBH, animals are exposed to increasingly warm temperatures associated with climate change. However, the combined effects of GLY/GBH and temperature on terrestrial animals are unknown. Therefore, we investigated the effects of GLY and a GBH (Roundup®️ Weed & Grass Killer Super Concentrate; 5 mg acid equivalent GLY L-1) on the reproductive behavior (oviposition or egg-laying) of the variable field cricket, Gryllus lineaticeps under five different temperatures (20, 24, 28, 32, and 36℃). Females chose to lay more eggs in substrate containing GBH at 32℃, and they increased egg-laying when multiple oviposition sites were available. Oviposition specialization increased at temperature extremes, suggesting temperature may modulate the tradeoff between maternal and offspring fitness because clumping eggs into a small number of sites reduces females’ predation risk while potentially reducing offspring fitness. There was a thermal mismatch between oviposition and offspring survival because the optimal temperature for oviposition was approximately 27-32℃, which is significantly warmer than the optimal temperature for egg survival (25℃). We are the first to examine interactions between temperature and GLY/GBH in a terrestrial animal and on oviposition in any animal. Our results suggest that temperature and the availability of oviposition sites may be more important than GLY or GBH when making egg-laying decisions.