Abstract
The management of insect pests under fluctuating temperatures has become an interesting area of study due to their ability to stimulate defense mechanisms against heat stress. Therefore, understanding insect’s physiological and molecular response to heat stress is of paramount importance for pest management. Aphids are ectothermic organisms capable of surviving in different climatic conditions. This study aimed to determine the effects of short-time heat stress on green peach aphid Myzus persicae under controlled conditions. In this study, short-time heat stress treatments at different temperatures 27, 30, 33, and 36°C with exposure times of 1, 3, 6, and 10 h, respectively, on the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and oxidants, such as malondialdehyde (MDA) and hydrogen peroxide (H2O2), were determined. The results showed that the short-time heat stress significantly increased the content of MDA of M. persicae by 71, 78, 81, and 86% at 36°C for the exposure times of 1, 3, 6, and 10 h, respectively, compared with control. The content of H2O2 increased by 75, 80, 85, and 88% at 36°C for the exposure times of 1, 3, 6, and 10 h, respectively, compared with the control. The SOD, POD, and CAT activities increased by 61, 76, and 77% for 1 h, 72, 83, and 84% for 3 h, 80, 85, and 86% for 6 h, and 87, 87.6, and 88% for 10 h at 36°C, respectively, compared with control. Again, under short-time heat stress, the transcription levels of Hsp22, Hsp23, Hsp27, SOD, POD, and CAT genes were upregulated compared with control. Our results suggest that M. persicae increased the enzymatic antioxidant activity and heat-shock gene expression as one of the defensive mechanisms in response to heat stresses.
Highlights
Myzus persicae (Sulzer) (Homoptera: Aphididae), known as the green peach aphid, is a highly adaptable and polyphagous insect pest that feeds on more than 400 plant species from 40 plant families, including many economically important crops (Kennedy et al, 1962; Stevens and Lacomme, 2017)
Adult aphids from the third generation were treated with four different temperatures, i.e., 27, 30, 33, and 36◦C, in a climatic chamber under the constant humidity of 60 ± 5% and the photo exposure time of 16:8 h light/dark (Ma and Ma, 2012) developed a new parameter, drop-off temperature (DOT), to describe the critical temperature at which an aphid drops off its host plant when the ambient temperature rises, finding that adults starved for 12 h had higher DOT values than those who were unstarved or starved for 6 h and that behavioral thermoregulation and energy acquisition were in competition
These findings indicate that when Hsp22, Hsp23, and HSP 27 (Hsp27) levels rise at high temperatures, these genes can support M. persicae in developing heat tolerance
Summary
Myzus persicae (Sulzer) (Homoptera: Aphididae), known as the green peach aphid, is a highly adaptable and polyphagous insect pest that feeds on more than 400 plant species from 40 plant families, including many economically important crops (Kennedy et al, 1962; Stevens and Lacomme, 2017). Green Peach Aphid and Heat Stress insect biology because they develop over a small temperature range, and their growth rate is highly dependent on temperature (Hulle et al, 2010; Durak et al, 2016). The defense responses of aphids to high temperatures are of great interest. The upper temperature threshold for the growth of populations of many aphid species has been estimated to be between 25 and 30◦C, while the lower temperature threshold has been estimated to be below 5◦C (Barlow, 1962). Previous studies indicate that M. persicae has the greatest tolerance to high temperatures (Hazell et al, 2010). The defense responses of Aphis pomi varied as a function of temperature at 28◦C and survived due to flexible enzyme activity
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