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Temperature thresholds and statistical modelling of larval Wuchereria bancrofti (Filariidea: Onchocercidae) developmental rates

Published online by Cambridge University Press:  01 February 1997

F. LARDEUX
Affiliation:
ORSTOM (Institut Français pour le Développement en Coopération), B.P. 529
J. CHEFFORT
Affiliation:
Institut Malardé, B.P. 30, Papeete, Tahiti, French Polynesia

Abstract

Developmental rates for Wuchereria bancrofti larvae maturing in the vector Aedes polynesiensis were estimated by analysing stage-frequency data consisting of counts of larval stages in mosquitoes reared at 20, 22·5, 25, 27·5, 30 and 32 °C. Base temperatures (i.e. low temperature thresholds) for W. bancrofti development were estimated by the x-intercept method and the model of Lactin et al. (1995). Resulting values were similar with both methods and were ≈12·5 °C for microfilariae (mf) in thorax, ≈17 °C for L1, 15·5 °C for L2 and 16·5 °C for L3. Upper thresholds estimated by the Lactin et al. model were 29·3 °C for mf, 29·1 °C for L1, 32·2 °C for L2 and 31·5 °C for L3. In addition, an original method was devised for computing the L3 upper threshold, by modelling L3 length shrinkage with temperature. It gave a value of 31·4 °C. At 32 °C, L2 and L3 stages exhibited altered morphology, larvae being shorter and wider than expected. The model of Lactin et al. described adequately the non-linear relationship between developmental rate and temperature, but a linear degree-day approach may be applied for temperatures below 27–28 °C.

Type
Research Article
Copyright
© 1997 Cambridge University Press

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