The aim of this research was to assess the larval instar number of Pissodes castaneus (De Geer) and to facilitate the study of its biology by identifying a reliable method to determine the instar of individual larvae. The larvae of this weevil were collected in central Italy in 2004, and their head capsules were measured by means of a binocular microscope.Headcapsule width and length data were analyzed using Hcap, a computer program that use the distribution of size measures to determine instar separation rules. To determine instar number, the Gaines and Campbell method, which represents the perfect geometric progression of size measures (DyarÕs rule) by a regression line, was also used. This study identiÞed four larval instars of P. castaneus and found that head capsule widths and lengths followed DyarÕs rule and reliably distinguished instars.
Instar Determination for Pissodes castaneus (Coleoptera: Curculionidae) Using Head Capsule Widths and Lengths / T. PANZAVOLTA. - In: ENVIRONMENTAL ENTOMOLOGY. - ISSN 0046-225X. - STAMPA. - 36:(2007), pp. 1054-1058. [10.1603/0046-225X(2007)36[1054:IDFPCC]2.0.CO;2]
Instar Determination for Pissodes castaneus (Coleoptera: Curculionidae) Using Head Capsule Widths and Lengths
PANZAVOLTA, TIZIANA
2007
Abstract
The aim of this research was to assess the larval instar number of Pissodes castaneus (De Geer) and to facilitate the study of its biology by identifying a reliable method to determine the instar of individual larvae. The larvae of this weevil were collected in central Italy in 2004, and their head capsules were measured by means of a binocular microscope.Headcapsule width and length data were analyzed using Hcap, a computer program that use the distribution of size measures to determine instar separation rules. To determine instar number, the Gaines and Campbell method, which represents the perfect geometric progression of size measures (DyarÕs rule) by a regression line, was also used. This study identiÞed four larval instars of P. castaneus and found that head capsule widths and lengths followed DyarÕs rule and reliably distinguished instars.File | Dimensione | Formato | |
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