THE RELATIONSHIP BETWEEN CDC LIGHT-TRAP AND HUMAN-BAIT CATCHES OF ENDOPHAGIC SANDFLIES (DIPTERA, PSYCHODIDAE) IN THE PERUVIAN ANDES

A study was carried out in the Peruvian Andes to test the suitability of CDC light traps for monitoring changes in the human-landing rate of endophagic phlebotomine sandflies, following house-spraying with pyre throid insecticide. On four pairs of consecutive nights, sandflies wer e caught inside eight sprayed and eight unsprayed houses, either by hu man bait or by CDC light traps, The sandflies Collected were Lutzomyia verrucarum (97%) and Lu.peruensis (3%), both probable vectors of Leis hmania peruviana, and the species composition was unaffected by house- spraying. A non-linear relationship was detected between light-trap an d human-bait catches, but the relationship did not diverge significant ly from linearity within the range of sandfly abundance found in most houses in the endemic area (i.e. between 3 and 200 sandflies/house-nig ht), and did not differ significantly between sprayed and unsprayed ho uses. However, light trap catches had a significantly lower proportion of blood-fed females in sprayed than in unsprayed houses, probably du e to an insecticidal effect on post-blood-feeding behaviour. The propo rtion of Lu. verrucarum was significantly higher in light trap than in human bait catches, indicating that Lu.peruensis is either more anthr opophilic or less phototropic than Lu. verrucarum.