Meeting Abstract

P3-4  Monday, Jan. 6  Glyphosate in a warming world: Effects on lifespan, feeding, and food conversion efficiency in a field cricket, Gryllus lineaticeps WHITLOCK, JR*; VO, CP; STAHLSCHMIDT, ZR; U Pacific; U Pacific; U Pacific

The use of the herbicide glyphosate (GLY, the active ingredient in Roundup®) in the U.S. has increased over 200-fold since its introduction in the 1970s, and U.S. farmers now spray enough GLY to apply 1 kg onto every hectare of cropland. Historically GLY was marketed as non-toxic to animals, but recent work indicates acute and chronic toxicological effects of GLY across animal taxa—from insects to humans. Along with increasing GLY exposure, animals are expected to experience warmer temperatures due to climate change. Therefore, we studied the independent and interactive effects of GLY and warming on lifespan, food intake, and food conversion efficiency during adulthood in the variable field cricket, Gryllus lineaticeps. Half of the crickets were provided with GLY in drinking water (5 mg / l H2O as in other insect studies) while the remaining were provided with normal (GLY-free) drinking water. Crickets’ thermal environments were also manipulated—that is, crickets underwent a 2 × 2 factorial manipulation of GLY and temperature treatments. Half of the crickets experienced a control temperature cycle (19°C - 38°C each day), which averaged rearing temperature and fluctuated similar to microhabitats used by adult G. lineaticeps in the field. The remaining crickets experienced a warming temperature cycle (23°C - 42°C each day), which had the same thermal variation as the control temperature treatment but with a 4°C higher mean temperature to reflect projected warming. Ours is the first study to examine interactions between GLY and warming in an insect thereby providing critical insight into understanding the complex dynamics among herbicides, plants, and herbivores in the context of climate change.