Larval differences between sympatric populations from Kaduna, West Africa, of species A and B of the Anopheles gambiae group
Reid, J.A.
Parassitologia 15(1): 87-98
1973
ISSN/ISBN: 0048-2951 PMID: 4788364 Document Number: 65033
Examination of small samples of species A and B of the group of Anopheles gambiae Giles from Kaduna, Nigeria, where they occur together, showed that most of the larvae can be identified as A or B by external characters. The distinguishing characters of the larvae, as found in a study of 37 examples of species A and 39 of species B from laboratory colonies, are dealt with in this paper. Examination of the larval hairs showed that, in addition to prothoracic hair no. 1, which is known to have fewer branches in species A than in species B, a few hairs on the posterior abdominal segments had useful differences between the two species in the range and mean number of branches. Species A has more branches than species B on the relevant posterior abdominal hairs, but the overlap of the ranges of variation was too great for the hairs to be used singly to identify individual examples. When the sum of the branches on both the left and right hairs of a pair on each larva was taken, the number of larvae in the overlap was considerably reduced. If the sums of the branches on more than one pair of hairs were added (or subtracted in the case of prothoracic hair no. 1), over 90% of the larvae could be identified. The most effective combination used, involving three pairs of hairs, enabled the identification of 93% of the larvae to which it could be applied. When other indicative characters were used as well, the proportion identified was raised to 97%. Further work is needed to show whether the characters of the larval hairs can be used to identify larger samples of larvae at Kaduna and, if so, the extent of the area over which they are useful.