Mepraia spinolai in the Southeastern Pacific Ocean Coast (Chile) - First insular record and feeding pattern on the Pan de Azúcar Island

Abstract

In a field collection performed at Pan de Azúcar Island in Northern Chile (Miles 1976, Schenone et al.1980, Schofield et al. 1982, Apt & Reyes 1986, Sagua 1988, Schenone & Rojas 1989, Lent et al. 1994.M. spinolai is the only specie of Triatominae with wing polymorphism. It is an aggressive insect which will feed on any host, even during daylight (Gajardo-Tobar 1953, Lent & Wygodzinsky 1979, Sagua 1983, Frías et al. 1987, Canals et al. 1998. It is almost entirely sylvatic, and only occasionally reported at homes or in peridomestic habitats (Schenone et al. 1980, Schofield et al. 1982, Aguilera et al. 1986).This study records details of fieldwork performed at Pan de Azúcar Island, located in Chilean Administrative Región III. The island is a seabirds and marine mammals national park reservation where M. spinolai was collected in all instars of its life cycle. MATERIALS AND METHODSPan de Azúcar island (Lat. 26' 08' S, Long. 70' 40' W) is located 800 m from its neighboring coast. It is 182 m high and 5 km distant from the outlet stream of the same name (Pan de Azúcar), which marks the limit between the regions of Antofagasta and Atacama. In general the mainland coast of this area is stony and not very high, but is backed by a range of mountains, which can reach 595 m in height. The marine climate shows only slight temperature changes during the day, cloudiness that disperses at midday, high humidity, strong sunshine from the east, marine winds mainly from the west, and a saline atmosphere and soil. The Pan de Azúcar island flora and fauna are similar to those of the littoral plain of the continental area of the Atacama Desert. Cacti and bushes, marine birds, carrion birds, lizards and the marine mammals Lutra felina (sea otter) and Otaria flavescens (sea lions) are predominant on the island.Currently this area is a natural park reservation, since Spheniscus humboldti, (Humboldt penguin) and L. felina (marine otter) have their reproductive habitats in this island.Field and laboratory procedures -Triatomines were collected during the summer of 1995 by manual sampling, using blunt forceps. The insect presence was investigated under stones and in bird nests and involved the collection of active walking bugs. Some bugs were also captured as they approached the researchers (nymphs II and III). Bugs were maintained in flasks with corrugated filter paper as a resting site. Labelled flasks were sealed and transported to our laboratory.In the laboratory, live and dead triatomines were counted and instars were noted. The live bugs were

Biogeographic origin and phylogenetic relationships of Mepraia (Hemiptera, Reduviidae) on islands of northern Chile

“…Our study shows that both dispersal and vicariance hypotheses are not exclusive and have played major roles in the biogeographic origin of individuals of Mepraia in islands of northern Chile. Sagua et al [10] suggested that the occurrence of individuals of M. parapatrica in Pan de Azúcar Island could be explained through passive transport by marine birds. Mepraia species have opportunistic habits, being able to feed on birds both in the continent [40,41] and in the island [10].…”

“…Sagua et al [10] suggested that the occurrence of individuals of M. parapatrica in Pan de Azúcar Island could be explained through passive transport by marine birds. Mepraia species have opportunistic habits, being able to feed on birds both in the continent [40,41] and in the island [10]. Triatomines hidden in cracks may be attracted to birds and make their way between the feathers to feed; they may attach to the feathers and the stylet would pricks the skin.…”

“…The T. cruzi life cycle alternates between triatomines and mammalian host species, while birds and reptiles are refractory to infection [51,52]. It has been reported that individuals of M. parapatriica feed mainly on seabirds and reptiles in Pan de Azúcar Island [10]; however, hosts have not been studied in Santa María Island due to the recent description of the occurrence of kissing bugs [11]. Strikingly, triatomines infected with T. cruzi were reported both in Pan de Azúcar and Santa María Islands, raising the question of how the T. cruzi life cycle is completed with the high abundance of hosts refractory to infection.…”

“…Island populations of Mepraia genus were reported inhabiting in Pan de Azúcar Island at 1.8 km from the continent (26˚9'S) in the Atacama Region [10]; these individuals were characterized as M. parapatrica using morphological approaches [6]. Insular individuals of Mepraia were also reported on Santa María Island at 1.9 km from the continent (23˚28' S) in the Antofagasta Region [11] an area located between M. gajardoi and M. parapatrica distribution [7].…”

“…The first hypothesis is related to the origin of insular triatomines by dispersion. Sagua et al [10] suggested that passive transport by marine birds might explain the occurrence of individuals of Mepraia on Pan de Azúcar Island. An alternative hypothesis explains that the populations on islands resulted from vicariant processes splitting the continent and islands due to sea level changes [6].…”