Some nutritional and chemical properties of the larval habitats of certain species of Culicoides (Diptera: Ceratopogonidae).

Abstract

Definition of the habitats of certain species of Culicoides by the examination of some chemical properties of the larval environment was made using standard soil analysis methods. Aquatic substrates located at the edges of streams and ponds were taken in various parts of Virginia and adjoining states. A portion of each sample was submitted to the University Soil Testing Laboratory for analysis of percentage of organic matter, the amounts of calcium (CaO), magnesium (MgO), phosphates (P2O5.), potash (K2O) and the pH. The other portion of each sample was held at room temperature to allow the insects within to complete their development and to emerge as adults. Culicoides furens (Poey), C. hollensis (Melander & Brues), and C. variipennis (Coquillett), probably subspecies variipennis, were reared from substrates analyzed to be high in percentage of organic matter and minerals. C. variipennis was found in only fresh water substrates and never with C. furens and C. hollensis. Culicoides crepuscularis Malloch and C. stellifer (Coquillett) were found in substrates analyzed to be moderate to high in soil nutrients; C. baueri Hoffman and C. piliferus group were present in substrates moderate to low in nutrients; and C. biguttatus (Coquillett) and C. loisae Jamnback were present in substrates low in nutrients. The species C. haematopotus Malloch and C. spinosus Root & Hoffman were found to occur in a wide range of soil nutrients.