AN ASSOCIATION BETWEEN PHLEBOTOMINE SANDFLIES AND APHIDS IN THE PERUVIAN ANDES

As the composition of natural sugars in the diet of adult sandflies (D iptera: Psychodidae: Phlebotominae) may affect the development of Leis hmania (Kinetoplastida: Trypanosomatidae) in sandfly guts, and so play an important role in the epidemiology of leishmaniasis, there is incr easing interest in the sources of sugars for wild sandflies, Advanced chromatography techniques have provided indirect evidence that wild sa ndflies feed on honeydew, a substance released by aphids (Hemiptera: A phididae) when feeding. Our objective was to determine whether sandfly density can be influenced directly by the local density of aphids. Ap hid density was determined by counting absolute numbers of aphids on a lfalfa stems in Purisima Valley, Peru, where sandflies transmit Leishm ania peruviana causing Andean cutaneous leishmaniasis (uta). Sandfly r elative abundance was measured using sticky trap sampling repeatedly i n alfalfa fields. Lutzomyia verrucarum accounted for 92% of the total sandflies collected. As there was a female bias in sandflies collected close to houses, only the numbers of male sandflies were used in anal ysis. Most of the adult aphids found feeding on alfalfa were either Th erioaphis trifolii forma maculata (97%) or Acyrthosiphon pisum (3%). B y regression analysis, a significant relationship was found between th e density of Lu.verrucarum males and the density of adults of both aph id species. This is the first ecological study to support the hypothes is that aphid honeydew may be a source of sugar for sandflies.