SCIENTIFIC NOTE Occurrence of Lepidopterism Caused by the Moth Hylesia nigricans (Berg) (Lepidoptera: Saturniidae) in Rio Grande do Sul State, Brazil1

Lepidopterism by Hylesia nigricans (Berg) moth is recorded for the first time in southern Brazil. Preventive strategies of control are proposed based on information on the biology and ecology of this moth. kEy wORDS: Dermatitis, host-plant, southern Brazil, urticating moth The genus Hylesia hübner is exclusively Neotropical and comprises approximately 100 species of moths (Lamy et al. 1984). at population peaks some species of Hylesia pose a public health problem, causing epidemic outbreaks of dermatitis in human beings (Carrera 1991, Scoble 1992). Such dermatitis can be caused by caterpillars (erucism) as wells as by adults (lepidopterism), the latter case occurring when urticating bristles are released from the abdomen of females (Lamy & Lemaire 1983, Rodriguez et al. 2004). Cases of lepidopterism caused by Hylesia spp. have been registered since the beginning of the last century in several countries of Central e South america, including Mexico, Costa Rica, French Guiana, Surinam, venezuela, Peru, argentina and uruguay (Leger & Mouzels 1918; Fornés & hernández 2000, 2001; willat et al. 2003). In Brazil, there are records for the amapá, Minas Gerais and São Paulo States (Gusmão et al. 1961, Mascarenhas et al. 1980, Glasser et al. 1993). Hylesia nigricans (Berg) is present from Southeastern Brazil down to uruguay and argentina (Silva et al. 1968, Lemaire 2002). adults have sexual dimorphism and intraspecific variation (Specht et al. 2006). The females are larger, more robust and darker than the males, which can have color variations in their wings and dark or yellow abdomen (Mabilde 1896, köhler 1931, Specht et al. 2006). The egg masses are brownish-orange, formed by layers of eggs covered by urticating bristles, which are released from the abdomen tip of females at oviposition. Caterpillars of H. nigricans have gregarious habits, and have been observed in various families of host plants (Mabilde 1896, Bourquin 1945, Specht et al. 2006), being considered a pest of several cultivated plants, such as Ilex paraguariensis St. hil. (Bourquin 1945, Quintanilha 1946, Silva et al. 1968, Penteado 1995). Cases of lepidopterism caused by H. nigricans are cited for argentina and uruguay (Pesce & Delgado 1971, arias 1981, willat et al. 2003). Recently, aspects of the biology of the H. nigricans have been described in detail by Specht et al. (2006). During the months of December and January of 2000 many cases of dermatitis caused by H. nigricans were reported at the valley of the Paranhana River in Rio Grande do Sul, South Brazil. The official records of occurrence were higher in the municipalities of Igrejinha and Três Coroas (L.M.G. Diefenbach, pers.com.). In Igrejinha, the Secretaria de Saúde do Estado do Rio Grande do Sul recorded 168 cases of dermatitis, but probably many others were not duly recorded. There is a lack on the knowledge about this moth, mainly concerning its population biology. The aims of the present July August 2007 Neotropical Entomology 36(4) 613 work are (i) to document the population outbreak of H. nigricans at Igrejinha and Três Coroas and (ii) to propose control strategies to prevent future occurrences. The Vale do Rio Paranhana (29o34’S, 50o48’W) is located at the lower part of the Northeastern Slope, at the South boundaries of the Serra Geral (a major mountain range in Southern Brazil) at Rio Grande do Sul State, with altitudes varying from 20 m to 773 m. According to the Köppen classification, its climate is Cfa (subtropical humid) (Mota 1951) with temperatures varying from 0oC in the winter to 40oC in the summer. The region embraces areas of Dense Rain Forests and Mixed Rain Forests, and is included within the “Atlantic Forest Biosphere Reserve” already recognized by the Man and Biosphere Program Council of UNESCO. Igrejinha has approximately 25,000 inhabitants, its territorial extension is 162 km2, and it is about 85 km away from Porto Alegre, the capital of the State. Três Coroas is 92 km away from Porto Alegre and 7 km away from Igrejinha, has a total area of 166 km2, and it is located along the RS-115 State Highway, being at the foot of the previously mentioned Serra Geral. Both towns are surrounded by areas of native vegetation, which makes the contact between their urban areas and the Floresta Atlantica very close. Field expeditions were carried out in December 2000 and January and December 2001 in Igrejinha and Três Coroas. The vegetation at and around the points where infestations had been reported was visually inspected for host plants, adults, eggs and larvae of H. nigricans in the central and peripheral regions of the towns. The egg masses collected were reared and monitored on host plants inside breeding cages, in laboratory, until the individuals became adult. For the sampling of adults “Luiz de Queiroz” light traps were used (Silveira Neto & Silveira 1969). Two traps were placed in each town, close to the edge of the forest, at two different collecting spots per year. The traps lights were kept on from 06:00 PM to 06:00 AM and checked at 00:00 AM on each sampling occasion, totalizing 96 hours of sampling effort. Data on host plants and the biology of H. nigricans were recorded in the field and supplemented by literature review (Mabilde 1896, Köhler 1931, Bourquin 1945, Quintanilha 1946, Silva et al. 1968, Lamy & Lemaire 1983, Penteado 1995, Specht et al. 2006). The insects collected in the light traps were identified at order level and placed in 70% alcohol. The Macrolepidoptera (sensu Kristensen 1998) were separated by morphotypes and H. nigricans were identified according to Lemaire (2002) and Spetch et al. (2006). The individuals collected manually were mounted and added to the Lepidoptera Reference Collection of the Zoology Department, Federal University of Rio Grande do Sul (UFRGS). The plants in which egg masses were found were new records for families and species of host plants for the immature stages of H. nigricans: Lithraea brasiliensis March. (Anacardiaceae), Schinus terebinthifolius Raddi (Anacardiaceae), Luehea divaricata Mart (Tiliaceae) and Allophylus edulis (St. Hill.) Radlk. (Sapindaceae). Eggs collected in January, only hatched the following October and November. Although no quantitative study was carried out concerning the developmental time of the egg masses of H. nigricans, infestations of larvae also occurred in the field during these same months in Igrejinha and Três Coroas. This pattern is similar to the one described by Mabilde (1896) and Bourquin (1945), indicating that H. nigricans has univoltine cycles. Adults emerged in the laboratory ca. two to three weeks after pupating. In the first year of sampling, from the total of 1,222 Macrolepidoptera, 484 were H. nigricans (Fig. 1). Of these, 364 were males and 120 females, a sexual ratio of 3:1. From 6 p.m. to 0 a.m., only 45 H. nigricans were collected, all the other 90.7% were recorded between 0 a.m. to 6 a.m. A peak of activity in the latter half of the night was also observed for other Hylesia species, corresponding with their reproductive characteristics (Janzen 1984, Fornés & Hernández 2000). This population boom close to human populations may have occurred due to the increasing expansion of the urban areas, with buildings being constructed very close to the forested areas. This way, an ever-growing contact zone between forests and urban environments is yielded and the presence of wild life in urbanized spaces is inevitable. In the case of this study, in particular, there is the added condition that public squares have many plants that may host H. nigricans and strong artificial night lighting. These elements are very attractive to this species and coincide with its nocturnal activity period (Fornés & Hernández 2000). In a study by Glasser et al. (1993), these aspects are corroborated: in epidemic outbreaks in the Vale da Ribeira and in the Baixada Santista, in São Paulo State, the vegetation of affected urban areas was important for these moths, and a high density of these insects was recorded close to buildings with permanent lighting and light-colored walls. Based on sampling field observations and biological data for other species of Hylesia (see Fornés & Hernández 2000), in December 2000 we suggested that the City Councils of Igrejinha and Três Coroas monitor the situation. Measures suggested included the recording of dermatitis cases and basic control measures, such as the manual destruction of