Demography of Soybean Aphid (Homoptera: Aphididae) at Summer Temperatures

Abstract

Soybean aphid, Aphis glycines Matsumura, is now widely established in soybean, Glycine max L., production areas of the northern United States and southern Canada and is becoming an important economic pest. Temperature effect on soybean aphid fecundity and survivorship is not well understood. We determined the optimal temperature for soybean aphid growth and reproduction on soybean under controlled conditions. We constructed life tables for soybean aphid at 20, 25, 30, and 35 degrees C with a photoperiod of 16:8 (L:D) h. Population growth rates were greatest at 25 degrees C. As temperature increased, net fecundity, gross fecundity, generation time, and life expectancy decreased. The prereproductive period did not differ between 20 and 30 degrees C; however, at 30 degrees C aphids required more degree-days (base 8.6 degrees C) to develop. Nymphs exposed to 35 degrees C did not complete development, and all individuals died within 11 d. Reproductive periods were significantly different at all temperatures, with aphids reproducing longer and producing more progeny at 20 and 25 degrees C than at 30 or 35 degrees C. Using a modification of the nonlinear Logan model, we estimated upper and optimal developmental thresholds to be 34.9 and 27.8 degrees C, respectively. At 25 degrees C, aphid populations doubled in 1.5 d; at 20 and 30 degrees C, populations doubled in 1.9 d.

Development and Parasitism byAphelinus certus(Hymenoptera: Aphelinidae), a Parasitoid ofAphis glycines(Hemiptera: Aphididae)

“…in temperate climates exhibit various diapause regimens (Bernal et al 2001, Tatsumi andTakada 2006), and it is likely that A. certus is capable of entering diapause at similar temperatures. The lower threshold of development of the soybean aphid is 8.6ЊC (McCornack et al 2004), 3ЊC lower than that of A. certus pupae. Thus, the soybean aphid will be able to complete development earlier in the season than A. certus.…”

“…The optimal temperatures of development for the egg-mummy and mummy-adult life stages of A. certus are both greater than the optimal temperature for development of the soybean aphid (i.e., 27.8ЊC) (McCornack et al 2004), suggesting that A. certus is more tolerant than soybean aphid of high temperatures. The population doubling time, intrinsic rate of increase, and gross fecundity of the soybean aphid have been shown to be lower at 30ЊC than at 25ЊC (McCornack et al 2004).…”

“…The population doubling time, intrinsic rate of increase, and gross fecundity of the soybean aphid have been shown to be lower at 30ЊC than at 25ЊC (McCornack et al 2004). Considering that A. certus does not experience temperature-dependent mortality and parasitism rate increased with temperature, biological control of soybean aphid by A. certus may be enhanced by warm weather.…”

“…Soybean aphid (Aphis glycines Matsumura) is an economically important pest of soybean (Glycine max L.) in North America (McCornack et al 2004). Since its arrival in 2000, the soybean aphid has spread throughout the entire soybean growing region (DiFonzo 2009).…”

Biotic and Abiotic Influences on Within-Plant Distribution of Soybean Aphid (Hemiptera: Aphididae: Aphis glycines)

“…Degree days were calculated by hourly intervals and accumulations determined by summing across hours and days. Calculations were based on a minimum developmental threshold for A. glycines of 8.6uC (McCornack et al, 2004), and hourly degree days were calculated as the area of a trapezoid, specifically:…”