Neotrop Entomol (2016) 45:33–43 DOI 10.1007/s13744-015-0341-2 ECOLOGY, BEHAVIOR AND BIONOMICS Population Dynamics of the Swallowtail Butterfly Battus polystictus polystictus (Butler) (Lepidoptera: Papilionidae) with Notes on Its Natural History 1 2 1 1 VW SCALCO ,ABBDE MORAIS ,HPROMANOWSKI ,NOMEGA 1Depto de Zoologia, Univ Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil 2Depto de Biologia, Univ Federal de Santa Maria, Santa Maria, RS, Brasil Keywords Abstract Aristolochia, ecological transition zone, Battus polystictus (Butler) is a butterfly from the Neotropical region, oc- mark-release-recapture, Neotropical region curring in the Atlantic Forest and Pampa biomes. It is commonly found in Correspondence forest fragments surrounded by meadow formations, subjected to marked VW Scalco, Graduate Program in Animal seasonal changes. Here, we report the population dynamics of Biology, Federal Univ of Rio Grande do Sul, Bento Gonçalves Ave. 9500/43435, Postal B. polystictus at a high latitude environment and provide notes on its Code 91501-970 Porto Alegre, RS, Brasil; natural history. Population parameters were estimated on a 12-month [email protected] mark-recapture program and the seasonality of resources investigated Edited André VL Freitas – Unicamp by exhaustive mapping of host-plants and flowers. The number of butter- flies per day was not stable during the year, ranging from zero (winter) to Received 12 February 2015 and accepted 29 22 (summer); the sex ratio was always male biased (3M:1F). The age struc- September 2015 Published online: 20 November 2015 ture was not constant, with an increase of older individuals toward sum- mer. The population density was positively correlated with temperature, * Sociedade Entomológica do Brasil 2015 relative humidity, and day length. The residence time was lower for males, while the vagility was lower for females; the increment of resources at forest edges seems to increase the likelihood of occurrence of both sexes. The results shown here suggest that South Brazilian populations of B. polystictus have high ecological demands for spring and summer condi- tions, avoiding winter in diapause. Introduction marked seasonal variation regarding temperature of photo- period. Since these abiotic variables are considered two of Population dynamics is a central theme in ecology, unifying the most important factors shaping developmental patterns concepts that permeate this field of science. It is a field of and behavior of swallowtail butterflies (Tyler et al 1994, extensive application for understanding pest species, epide- Scriber et al 1995,Lehnertet al 2012), the population dynam- miology, biological control, and conservation (Price et al ics at high latitude sites should be better investigated to 2011). In recent years, knowledge on butterfly biology has improve the mechanistic understanding of population pa- increased due to research efforts on natural history and pop- rameters that changes along the Neotropics. ulation dynamics of many different species, and several of The New World Troidini genus Battus Scopoli has 12 spe- them in the past three decades have been focused on cies with widespread distribution from Central Argentina to Troidini from the Neotropical region (Brown et al 1981, the South United States. One characteristic of this group of Otero & Brown 1986, Freitas & Ramos 2001,Paim&Di butterflies is the exclusive use of host-plants from the genus Mare 2002,Beirãoet al 2012, Herkenhoff et al 2013). Most Aristolochia (Brown et al 1981, Weintraub 1995, Klitzke & of these studies did not find marked fluctuations for the Brown 2000), from which larvae sequester secondary com- analyzed populations, perhaps because most Troidini species pounds during larval development to use as chemical de- were from low latitudes and were not subjected to any fense against predators by improving unpalatability (Nishida 34 Scalco et al. &Fukami1989,Feeny1995). Some Battus species are sensi- around 24% of the municipality area (Silveira & Miotto 2013). tive to environmental perturbations, requiring habitats with The landscape vegetation consists of a mosaic of formations intermediately to highly preserved conditions, making them typical from the ecological transition zone between the a useful bioindicator to monitor anthropic disturbance (Tyler Atlantic Forest and Pampa biomes, ranging from open grass- et al 1994). Thus, knowing the dynamics and ecological pref- lands in the northern face to semi-deciduous seasonal forest erences of such species is a cost-efficient tool for habitat in the southern face (Fig 1). The area is interconnected with monitoring. some primary forest remnants from other hills and shows an Battus polystictus polystictus (Butler) (hereafter Battus advanced stage of ecological succession (Backes 2000). The polystictus) has its distribution restricted to the Atlantic climatic and edaphic factors have a strong influence on the Rainforest and Pampa biomes, occurring from south and area physiognomy, determining the occurrence of clean and southeast regions of Brazil to northeastern Paraguay and shrub meadows, forest fragments, and swamps. According Argentina (Tyler et al 1994). Adults display large black wings to the Köppen-Geiger classification (Peel et al 2007), the with greenish-yellow blots at the wing margins, showing sex- region climate is humid subtropical (Cfa). The annual average ual dichromatism regarding abdomen coloration. They usu- temperature is 19.5°C and the annual rainfall 1324 mm ally fly high and fast, with short periods of gliding in the (Menegat et al 2006), with hot and dry summers (average woodland edges and moist forests, from spring to autumn temperature—24.9°C, average rainfall—98.5 mm) and cold (Núñez-Bustos 2010), generally near hillsides and slopes and wet winters (average temperature—15.2°C, average (Scalco 2012). The species is essentially nectarivorous and rainfall—131 mm). A climatic diagram for the study area dur- visits a wide variety of flowers (DeVries 1987). ing samplings is presented in Fig 2. The objective of the present study was to describe the population dynamics and some aspects of the natural history Butterfly sampling and parameters analyzed of B. polystictus in a seasonal environment at the southern- most area of Brazil. Our hypothesis is that populations of We used the technique of mark-release-recapture (MRR) to Troidini species from southern Brazil are subjected to differ- monitor the population of B. polystictus over a year, from ent environmental constraints when compared to northern November 2012 to October 2013. Field surveys were con- populations. We expect that population size will vary directly ducted 1–3 times a week, except during the winter when field with the day length and temperature, leading to adult local expeditions were done fortnightly. Butterfly sampling was extinction during later autumn, winter, and early spring. The carried out between 09:00 am and 04:00 pm, always on choice to conduct the present study was also related to the sunny days, with temperatures between 15 and 35°C and selective behavior of B. polystictus, mainly for moist forests mild breeze. The sampling counted 45 field days scoring ap- located near hillsides with a low to medium level of distur- proximately 360 net-hours of sampling effort. Butterflies bance. The contact zone between the Atlantic Forest and captured were marked and recaptured along a 2500-m tran- Pampa provides a heterogeneous landscape without the pre- sect located at the southern face of the Morro do Coco. The dominance of forest or meadows. Adult resources and larval trail used for field surveys crossed different vegetation for- host-plants are expected to vary between meadow and for- mations (Fig 1) and was divided into 50-m sectors to allow est fragments; thus, it is expected that B. polystictus will the identification of capture/recapture point of each butter- occur preferentially in forest habits in the study site. High fly. Butterflies were captured with an insect net and marked ecological demands are common to all endangered species on the underside of discal cells on both hindwings with a of Troidini, and, despite B. polystictus are not being consid- unique numerical code, and then released. The marks were ered a threatened butterfly, we expect that this species will made using a felt-tipped pen with a non-toxic-permanent-ink be better suited by landscapes richer in resource availability. (Ehrlich & Davidson 1960). For each butterfly, the following aspects were recorded: numerical code, time of capture, sex, age, forewing length, sector of capture, and vegetation type Material and Methods in the sector of capture. Sexing was done through the inspection of genitalia and Study site dorsal abdomen color (males have an evident green- yellowish coloration). The sex ratio was estimated monthly The study was carried out at the locality of Morro do Coco, a by scoring the sexual rate observed in each field survey. 300-ha, 131-m high granitic mount (Knob 1978) located in the The age of individuals was estimated visually by the wing Viamão Municipality, state of Rio Grande do Sul, southern wear conditions of captured butterflies (Ehrlich & Gilbert Brazil (30°15′52″S,51°02′47″W). Situated in the shores of the 1973). We scored three categories according to wing wear Guaíba Lake, the study site belongs to the granite mountain (Freitas 1993): young (intense color, very bright), interme- chain present in the surroundings of State Capital, occupying diate (faded color, less bright), and old (very faded color, Population Biology of Battus polystictus 35 Fig 1 Landscape formations present at Morro do Coco, Viamão, RS, Brazil. Meadow (a), hill slope forest (b), lowland moist forest (c), and Restinga forest (d). some damage to the wing, partially transparent). The age between months using appropriate parametric or non- structure was calculated monthly considering both sexes to- parametric tests. The vegetation formations were catego- gether, by scoring the proportion of each category present in rized in four different types: meadows, hill slope forests, each field survey. Forewing length of captured butterflies was lowland moist forests, and Restinga forests.