Reproductive Development of Lygus hesperus (Hemiptera: Miridae) Adults Under Constant and Variable Temperatures.

Abstract

As water for agriculture becomes less available in the semi-arid western United States, alternative irrigation strategies such as deficit irrigation may be necessary for continued crop production. Alternative irrigation practices in cotton (Gossypium spp. [Malvales: Valvaceae]) can result in episodic drought stress that alters temperature profiles within the crop canopy. These altered temperatures may influence populations of important pests such as Lygus hesperus Knight. Field studies often associate lower population densities of L. hesperus with limited irrigation. Recent studies of the thermal ecology of L. hesperus egg and nymphal development have demonstrated only subtle effects of the high, variable temperatures typical of moderate drought stress in cotton. However, influences of these conditions on L. hesperus adult reproductive development have not been studied. The reproductive development of L. hesperus adults was examined under constant (±0.2°C) and variable (±8°C) regimes at a low (15°C), moderate (22°C), and high (29°C) daily mean temperatures. No developmental differences were demonstrated between temperature regimes under moderate or high temperatures. At the low temperature, only the times to the occurrence of eggs, filled medial accessory glands, and filling seminal vesicles were shorter under variable regime, compared with the constant temperature. These results suggest that temporary, episodic increases in crop canopy temperatures caused by moderate drought stress are unlikely to impact L. hesperus population growth, and may only promote short-term displacement of adults into adjacent crops with preferable conditions.