We studied the life history and feeding habits of two coexisting and closely related sister species of Sialis (Sialis itasca Ross and Sialis velata Ross) from a reservoir and river in central Texas. Measurement of larval head capsules and emergence showed the two species to have 10 larval instars, and the seasonal distribution of immature and adult life stages showed synchronous, seasonal, univoltine life histories with a single cohort. Life history dynamics were somewhat faster in the river, probably due to higher temperatures during the larval growth periods. Larvae exhibited a more rapid larval development rate and earlier prepupal and adult emergence patterns relative to those reported from more northern latitudes. However, a univoltine life cycle appears to represent the norm for Sialis in geographic locations where water temperatures are not limiting to growth and suggests that evolutionary/genetic constraints play a greater role in regulating life history in these insects than environmental factors. Analysis of larval diets showed prey consumed by members of both populations consisted of ostracods, oligochaetes and chironomids.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 155 • No. 1