Meeting Abstract
P3-140 - Effects of temperature on oxygen consumption in the alfalfa leafcutting bee Earls, KN; Cruz, JM; Rinehart, JP; Greenlee, KJ*; North Dakota State University; Lynn University; USDA-ARS-Edward T. Schafer Agricultural Research Center; North Dakota State University kendra.greenlee@ndsu.edu
Measuring oxygen consumption in small insects can be difficult, especially at low temperature, because oxygen analyzers may not be sensitive enough to detect the low levels of oxygen consumed under such conditions. We tested a new technique for measuring oxygen consumption, Loligo microplate system, that was originally designed for use in aquatic insects. The microplate system has a 24-well glass microplate fixed with oxygen sensors in each well, allowing for measurement of up to 24 insects at a time. The entire unit can be placed in an incubator for use at varying temperatures and yields real-time measurements of oxygen consumption. We generated a thermal performance curve for the alfalfa leafcutting bee, Megachile rotundata to better understand how this species might respond to the changing climate during spring metamorphosis. Prepupal bees were stored over winter in 6°C and in summer placed in 29°C to initiate metamorphosis and adult development. After 2 weeks, pupae were placed into one of 13 temperatures for measurement of oxygen consumption. Metabolic rates were measured over 2 h. To validate the microplate system, we repeated measurements at two of the temperatures, using closed system respirometry with a fuel cell oxygen analyzer. Readings between the two systems were similar. Bee metabolic rates increased with temperature in a non-linear way, peaking at ~35°C. After treatment, bees were placed in 29°C to initiate development to adults and to verify that bees were alive during the measurement. After 2 h at the highest temperature, 48°C, no bees developed to adults, indicating that performance declines at that temperature. The microplate system has several advantages that make it promising for measuring oxygen consumption in small, air-breathing insects.