The Effect of Temperature and Host Plant Resistance on Population Growth of the Soybean Aphid Biotype 1 (Hemiptera: Aphididae)

Abstract

A laboratory experiment was conducted to evaluate direct and indirect effects of temperature on demographic traits and population growth of biotype 1 of the soybean aphid, Aphis glycines Matsumura. Our objectives were to better understand how temperature influences the expression of host plant resistance, quantify the individual and interactive effects of plant resistance and temperature on soybean aphid population growth, and generate thermal constants for predicting temperature-dependent development on both susceptible and resistant soybeans. To assess indirect (plant-mediated) effects, soybean aphids were reared under a range of temperatures (15-30 °C) on soybean seedlings from a line expressing a Rag1 gene for resistance, and life history traits were quantified and compared to those obtained for soybean aphids on a susceptible soybean line. Direct effects of temperature were obtained by comparing relative differences in the magnitude of life-history traits among temperatures on susceptible soybeans. We predicted that temperature and host plant resistance would have a combined, but asymmetrical, effect on soybean aphid fitness and population growth. Results showed that temperature and plant resistance influenced preimaginal development and survival, progeny produced, and adult longevity. There also appeared to be a complex interaction between temperature and plant resistance for survival and developmental rate. Evidence suggested that the level of plant resistance increased at higher, but not lower, temperature. Soybean aphids required about the same number of degree-days to develop on resistant and susceptible plants. Our results will be useful for making predictions of soybean aphid population growth on resistant plants under different seasonal temperatures.

Effect of Temperature on Plant Resistance to Arthropod Pests

“…Research with the soybean aphid provides equivocal evidence that plant resistance increases at both higher and lower temperatures compared to a middle range of noninducing temperatures. Hough et al (2017) recorded a lower rate of survival of the soybean aphid on resistant plants compared to susceptible plants at all temperatures (range 15-30°C). However, whereas survival on the resistant soybean line decreased sharply between 25 and 30°C, survival was equally high at the same two temperatures on the susceptible line.…”

“…In the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), Hough et al (2017) reported consistently lower survival on a resistant soybean (Glycine max (L.) Merrill [Fabales: Fabaceae]) line compared to a susceptible line at temperatures that ranged from 15 to 30°C. However, whereas aphid survival was equally high at 25 and 30°C on susceptible soybeans, on resistant plants there was a sharp decrease in survival between 25 and 30°C.…”

“…In a study with the soybean aphid, Hough (2016) found that both survival and progeny production were lower on resistant soybean seedlings that had been conditioned at 20°C before infestation and transfer to 25°C compared to seedlings that were conditioned at 30°C.…”

“…The authors concluded that high temperature induced a high level of plant resistance. Using a different experimental approach, but with the same resistant soybean line as that used by Hough et al (2017), Hough (2016) found that when resistant soybeans were grown at 25°C and then conditioned for different periods of time at 20°C prior to infestation, aphid survival was progressively lower the longer plants were held at 20°C. This could mean that a decrease in temperature caused an increase in resistance.…”

“…An accumulating body of evidence indicates that a change in temperature elicits changes in plants that alter the expression of resistance to insect pests. In some cases temperature enhances resistance (Sosa 1979, Thindwa and Teetes 1994, Chen et al 2014, Hough 2016, Hough et al 2017; in others it weakens it (Cartwright et al 1946, Hackerott and Harvey 1959, McMurtry 1962, Isaak et al 1963, Kindler and Staples 1970, Wood and Starks 1972, Johnson et al 1980, Salim and Saxena 1991, Walters et al 1991, Harvey et al 1994, Richardson 2011, Chen et al 2014, Chirumamilla et al 2014. And in a few cases, temperature appears to have no effect on plant resistance (Dahms and Painter 1940, Jackai and Inang 1992, Randolph et al 2008.…”