Thermal biology, population fluctuations and implications of temperature extremes for the management of two globally significant insect pests
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Author list: Nyamukondiwa C, Weldon CW, Chown SL, le Roux PC, Terblanche JS
Publisher: Elsevier
Place: OXFORD
Publication year: 2013
Journal: Journal of Insect Physiology (0022-1910)
Journal acronym: J INSECT PHYSIOL
Volume number: 59
Issue number: 12
Start page: 1199
End page: 1211
Number of pages: 13
ISSN: 0022-1910
Languages: English-Great Britain (EN-GB)
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Abstract
The link between environmental temperature, physiological processes and population fluctuations is a significant aspect of insect pest management. Here, we explore how thermal biology affects the population abundance of two globally significant pest fruit fly species, Ceratitis capitata (medfly) and C. rosa (Natal fruit fly), including irradiated individuals and those expressing a temperature sensitive lethal (tsl) mutation that are used in the sterile insect technique. Results show that upper and lower lethal temperatures are seldom encountered at the field sites, while critical minimum temperatures for activity and lower developmental thresholds are crossed more frequently. Estimates of abundance revealed that C. capitata are active year-round, but abundance declines markedly during winter. Temporal autocorrelation of average fortnightly trap captures and of development time, estimated from an integrated model to calculate available degree days, show similar seasonal lags suggesting that population increases in early spring occur after sufficient degree-days have accumulated. By contrast, population collapses coincide tightly with increasing frequency of low temperature events that fall below critical minimum temperatures for activity. Individuals of C. capitata expressing the tsl mutation show greater critical thermal maxima and greater longevity under field conditions than reference individuals. Taken together, this evidence suggests that low temperatures limit populations in the Western Cape, South Africa and likely do so elsewhere. Increasing temperature extremes and warming climates generally may extend the season over which these species are active, and could increase abundance. The sterile insect technique may prove profitable as climates change given that laboratory-reared tsl flies have an advantage under warmer conditions. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords
pest management, Phenotypic plasticity, population dynamics, Thermal biology
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