Relevance of laboratory colonies of the vector in arbovirus research--Culicoides variipennis and bluetongue.

Relevance for laboratory colonies of Culicoides variipennis (Coquillett) in arbovirus research was determined during colonization by comparing a vector-competence characteristic for the parent (P) field and subsequent colonized generations. Three colonies established in 1972-1973 were used to determine whether each was representative of the field population from which it was derived for oral infection to 2 to 4 serotypes of bluetongue virus (BTV). Two colonies that were based on small numbers of females ovipositing did not represent the field population. Both appeared homogeneous to oral infection with different serotypes, and one was resistant to infection whereas the other was susceptible. The third colony, which was based on about 150 P females that had oviposited, was more representative of the field population: 1) oral susceptibility to BTV for the F6 was not greatly different from that of the P generation, and 2) the colony retained some heterogeneity for response to oral infection with different serotypes of BTV. The number and percentage of P females ovipositing and the numerical growth factor from the P to F1 were used to estimate whether a laboratory colony was apt to represent the field population from which it was derived.