Responses in metabolic rate to changes in temperature in diapausing Colorado potato beetle Leptinotarsa decemlineata from three European populations

Abstract

Many insects survive adverse periods in seasonal environments by entering diapause, a deep resting stage, during which energy consumption is typically low and gas exchange is in the form of a discontinuous gas exchange cycle (DGC). Because insects in high‐latitude environments are severely time constrained during summer, an effective diapause termination with careful regulation of metabolic rate is important. The present study examines whether diapausing Colorado potato beetles Leptinotarsa decemlineata Say originating from three latitudinally different regions in Europe differ in their quantitative or qualitative gas exchange patterns in response to an increasing temperature. Overall production of gaseous CO2, as well as qualitative patterns relating to the DGC, are measured at a late stage of diapause at four different temperatures in increasing order from 13, 18, 23 to 28 °C. Overall CO2 production is found to be lower in the two northern populations (61°49′N and 55°75′N) compared with the southernmost population (45°48′N) but increases as a function of temperature in all populations in a similar way. However, in the northern populations, raising the temperature increases the amount of CO2 discharged during single DGC peaks, whereas the DGC frequency remains relatively unchanged. By contrast, in the southernmost population, the amount of CO2 discharged during individual DGC peaks remains relatively unchanged, whereas the DGC frequency increases as a function of temperature. The observed differences may relate to water retention benefits or, alternatively, energetic benefits relating to heightened gas exchange efficiency in hypoxic or hypercapnic environments. Overall, the results suggest that, although populations of L. decemlineata may have similar thermal sensitivities, they have different qualitative strategies to regulate metabolic re‐activation at diapause termination.

Variability in metabolic rate and gas exchange patterns of the Colorado potato beetle of winter and prolonged diapauses

“…The active ventilation seen during the CO 2 bursts in Colorado potato beetles is also reported by Vanatoa et al (2006) and Kuusik et al (2016) and may be interpreted as means to shorten the open phase and reduce water loss (Kestler, 1985(Kestler, , 2003. Lehmann et al (2015) note that, in northern Colorado potato beetle populations, rising temperature increases the amount of CO 2 discharged during single DGE peaks, whereas the DGE cycle frequency remains relatively unchanged. This is interpreted as an energetic benefit relating to heightened gas exchange efficiency in underground hypoxic or hypercapnic environments.…”

“…Lehmann et al . () note that, in northern Colorado potato beetle populations, rising temperature increases the amount of CO 2 discharged during single DGE peaks, whereas the DGE cycle frequency remains relatively unchanged. This is interpreted as an energetic benefit relating to heightened gas exchange efficiency in underground hypoxic or hypercapnic environments.…”

“…This type of modification is also recorded by Lehmann et al . (), who report that, in European northwest populations of diapausing Colorado potato beetles, a rise in temperature increases the amount of CO 2 discharged during single DGE peaks, whereas the DGE cycle frequency remains relatively unchanged.…”

Consequences of diapause on post‐diapause development, reproductive physiology and population growth of Chilo partellus (Swinhoe)

“…A diapause strategy helps insects to adapt to changing environments and enhance their survival capacity (Neal et al, 1997;Lehmann et al, 2015), although there can be a cost to diapause (Jiang et al, 2010;Arbab, 2014). Diapause costs could be determined in the form of a decrease in adult body weight, fecundity, longevity, reproductive performance and reproductive investment by adults (Irwin & Lee, 2000;Win et al, 2013;Win & Ishikawa, 2015).…”

Changing Phenology of Potato and of the Treatment for its Major Pest (Colorado Potato Beetle) – A Long-term Analysis

“…In areas with warmer winters, Colorado potato beetle needs less accumulated heat compared to beetles from colder areas. Temperature influences both emergence dates as well as growth rates (Lehmann et al 2015) and diapause induction of beetles is mostly controlled by photoperiod. However, diapause can by modified by temperature and food quality (Hiiesaar et al 2016).…”