The effect of elevated temperatures on food conversion efficiencies of Coccinella septempunctata and Harmonia axyridis young adults feeding on Sitobion avenae
An analysis of existing data gained in a set of climate chamber experiments was conducted to compare food conversion efficiencies of young Coccinella septempunctata and Harmo-nia axyridis adults (Coleoptera: Coccinellidae) as natural enemies of Sitobion avenae (Homoptera: Aphididae) at elevated temperatures. The two species were treated at normal (Mean: 17.8°C, Max: 21.8°C, Min: 13.4°C) and elevated (Mean: 20.8°C, Max: 25.5°C, Min: 15.7°C) daily temperature profile from first instar to 10-day-old adult and fed S. avenae ad libitum. Elevated temperatures caused higher consumption rates in both coccinellids but different responses in weight gain and body fat accumulation within the first 10 days of adulthood. Harmonia axyridis males were poor converters of consumed biomass into body weight and H. axyridis females showed the lowest efficiencies for converting food into body fat content, particularly at elevated temperatures. These results show different temperature-dependent responses of C. septempunctata and H. axyridis and are discussed in relation to their different biology.
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