Methods in Anopheles Research - MR4

Chapter 7 : Taxonomy and Systematics7.1 Methods for Collecting and Preserving MosquitoesPage 1 of 12Chapter 7 : Taxonomy and Systematics7.1 Methods for Collecting and Preserving MosquitoesTheresa Howard, Ralph Harbach, and Yvonne LintonINTRODUCTIONThe primary purpose of this section is to provide uniform methods for the collection, preservation andrearing of material for the project. The emphasis here is on methods suited for obtaining Anophelesmosquitoes for taxonomic studies. Essential for this type of study is a large amount of uniformly preparedmaterial with all the stages individually associated, general information on bionomics and conspicuousenvironmental factors, and a sample from as many habitats as possible in the study areas. Importantconsiderations in selecting the methods and techniques adopted here have been simplicity and suitabilityfor use under field and laboratory conditions and standardisation and simplification of records andlabelling to minimise errors and to save time.COLLECTION RECORDSCOLLECTION FORM. A standard form (see attached) for recording all the data pertaining to a collectionhas been developed for the project. The form must be filled out in the field as completely as possible andthe remainder added in the laboratory. A pencil should be used for all entries. All measurements shouldbe indicated in the metric system. There is a minimum of writing to be done (only in lined open spaces) onthe form, the rest is to be done by circling or underscoring appropriate words or statements or by placingcheck marks or other signs in appropriate columns.COLLECTION OF ADULTSEQUIPMENT. The basic equipment and supplies needed for the collection of adults are (1) aspirators,(2) plastic vials, (3) covered cups (4) cages and (5) flashlight (torch).CAPTURING. Resting, landing or biting mosquitoes are readily collected with an aspirator one or a fewat a time and then transferred to individual collection vials or covered cups. It is always preferable tocapture mosquitoes with an aspirator but it may not be practicable when very large numbers areencountered. It is also possible to place a tube directly over a resting or biting specimen but to do thisnumerous tubes may be neededKILLING AND STORING. The most satisfactory killing tubes are charged with ethyl acetate but otherkilling agents may be used (e.g. chloroform). The killing tubes should be used exclusively for mosquitoes,and should ideally contain Plaster of Paris to absorb the killing fluid (strips of dry absorbent tissue paperor paper towelling may be used, but when these strips get damp they must be replaced with fresh dryones). The specimens must be removed from the killing tubes within a few minutes after beingintroduced.ISOLATING FOR OVIPOSITION. A number of species of mosquitoes which are very common as adultsare very seldom encountered as larvae and pupae and the immature stages and breeding sites of someof these are poorly known. To obtain the immature stages of these it is necessary to isolate live individualfemales collected in the field, induce them to oviposit and to rear all the stages from the eggs (see thesection on PROGENY REARINGS). It is also frequently desirable to identify cryptic species bychromosomes, enzymes or DNA using this technique for obtaining material. The progeny broods can bedivided for study using different techniques.