Phyllophaga lissopyge (Bates) (Coleoptera: Scarabaeidae: Melolonthinae) is reported for the first time from South America. Male sex pheromone response is described for P. lissopyge and two other co-occurring Phyllophaga species. Adults of P. lissopyge and P. menetriesi (Blanchard) flew to traps baited with methyl 2-(methylthio) benzoate whereas adults of P. obsoleta (Blanchard) flew irregularly to four different pheromone compounds. Adult seasonal activity is described from males captures in Rionegro, Antioquia, Colombia.
The New World genus Phyllophaga (s. lato) (Coleoptera: Scarabaeidae: Melolonthinae) encompasses 865 extant species, including 442 from Central America, 217 from Canada and the United States, 186 from the Caribbean Islands, and 109 from South America (Evans and Smith 2009). Some overlap of species distribution occurs between these regions. Both larvae and adults of various Phyllophaga species are economically important pests of a variety of agricultural crops such as bean, cassava, coffee, corn, ornamentals, pasture grasses, peanut, pepper, potato, and sugarcane (King 1984, 1996a, 1996b; Morón 1986, 2006; Londoño 1993; Salvadori and Oliveira 2001; Salvadori and Silva 2004; Espinosa-Islas et al. 2005; Pardo-Locarno et al. 2005; Ortega-Ojeda et al. 2007).
Evans and Smith (2009) reported 28 species of Phyllophaga in Colombia (Table 1). Restrepo-Giraldo et al. (2003), however, reported 29 species in Colombia including P. sericata Blanchard, a species not reported by Evans and Smith (2009). Serna-Patiño (2004) added P. gigantea based on light-trap captures in Pereira, Risaralda. We report here the first capture of Phyllophaga lissopyge (Bates) (Coleoptera: Scarabidae) in South America, bringing the total number of species listed from Colombia to 31.
In Colombia, Phyllophaga flight activity generally occurs during the two rainy seasons, either March to May or September to November (Vallejo et al. 1998; Pardo-Locarno et al. 2002; Serna-Patiño 2004; Villegas et al. 2006, 2008). After emerging from the soil, females release sex pheromones by opening the pygidium and extruding a gland from which the pheromone volatilizes (for photos, see Leal et al. 1993; Nojima et al. 2003; Zarbin et al. 2007). Sex pheromones identified from the Phyllophaga include methyl 2-(methylthio) benzoate from P. crinita (Robbins et al. 2003); methyl esters of three amino acids, including L-valine, from P. anxia and P. (Phytalus) georgiana (Zhang et al. 1997; Robbins et al. 2009); L-isoleucine from P. anxia and P. elenans (Zhang et al. 1997; Leal et al. 2003); L-leucine from P. lanceolata, (Nojima et al. 2003); and phenol and p-cresol from P. cuyabana (Zarbin et al. 2007). Furthermore, an extensive trapping study by Robbins et al. (2006) demonstrated the widespread use of the methyl esters of L-valine and L-isoleucine methyl ester in the mate-finding systems of >50 species of Phyllophaga in the United States and Canada. This manuscript is the first part of a study of trapping Phyllophaga spp. with sex attractants in various regions of Colombia.
Materials and Methods
The study site was located at the “La Selva” research station of the Corporación Colombiana de Investigación Agropecuaria in Rionegro, Antioquia, Colombia (latitude 6° 9′ 17.1792″, longitude -75° 22′ 52.845″, and 2150 m elevation). This site was chosen because of its history of abundant Phyllophaga populations. According to the Instituto de Hidrología, Meteorología y Estudios Ambientales station in Rionegro, Antioquia, the average temperature at the location is 17° C (8.0–25.0° C) and precipitation is 1800–2500 mm per year, largely falling in a bimodal pattern from April–May and September–October.
The methodology used in the present study was similar to prior studies (Zhang et al. 1997; Leal et al. 2003; Nojima et al. 2003; Robbins et al. 2003, 2006, 2008, 2009; Alm et al. 2004) that captured Phyllophaga adults using sex attractants. Cross-vane traps (see Robbins et al. 2006) were hung on a series of metal stakes such that the trap bottom was 1 m above the ground. A line of 12 traps, each separated by 20 m, were situated along the edge of a corn and cabbage field. Traps were maintained in the field from August 2003 to September 2004. Traps were emptied and rerandomized weekly. Pheromone lures were replaced every 4 weeks. Each trap was baited with an individual lure from the following: eight blends of the methyl esters of L-valine and L-isoleucine (100:0, 90:10, 80:20, 60:40, 40:60, 20:80, 10:90 and 0:100) (4 mg each rubber septa), L-leucine methyl ester (4 mg each rubber septa), methyl 2-amino benzoate (1 mg each rubber septa), methyl 2-(methylthio) benzoate (1 mg each rubber septa), and a control trap containing a blank septa. All lures were supplied by ChemTica Internacional, ( www.chemtica.com). After collection, insects were frozen until identification. All specimens were identified to species using characteristics of the male genitalia (Morón 2001, 2003). The identification of P. lissopyge was confirmed by Dr. María Milagro Coca-Abia (Centro de Investigaciones y Tecnologías Agroalimentarias, Zaragoza, Spain) by comparison with museum specimens. Local rainfall data were obtained directly from the Instituto de Hidrología, Meteorología y Estudios Ambientales station in Rionegro, Antioquia.
Checklist of the Phyllophaga from Colombia.
A male capture response curve was constructed for each Phyllophaga species to illustrate the proportional capture of males collected over the entire study with respect to pheromone treatment. The seasonal incidence of each species was also examined by plotting the number of captures versus weekly precipitation to reveal any correspondence between rainfall and adult activity.
A total of 156 males and no females were captured, representing three species of Phyllophaga. These included 135 P. (Phyllophaga) lissopyge, 20 P. (Phytalus) obsoleta, and 1 P. (Phyllophaga) menetriesi, representing 86.5, 12.8, and 0.7% of total captures, respectively. This is the first record of P. lissopyge from Colombia and South America.
Male pheromone response
For P. lissopyge, male captures were greatest in those traps baited with methyl 2-(methylthio) benzoate (97.8%, n = 132); the remaining males (2.2%, n = 3) all flew to Lleucine methyl ester (Figure 2). In contrast, P. obsoleta showed no clear preference for any pheromone treatment; males were recovered from 100% L-valine methyl ester (15.0%, n = 3), 10:90 L-valine methyl ester: L-isoleucine methyl ester (20.0%, n = 4), L-leucine methyl ester (25.0%, n = 5), methyl 2-(methylthio) benzoate (10.0%, n = 2), and untreated check trap (30.0%, n = 6). The single male P. menetriesi was captured in a trap baited with methyl 2-(methylthio) benzoate.
Adults of white grub species are commonly called “marceños” (March beetles) because many species fly in March. Phyllophaga lissopyge, however, was captured during every month of the year with the exception of August in both 2003 and 2004 (Figure 3). Almost half of all captures (48.1%) occurred during the four months of highest precipitation, March to June 2004 (Figure 3). Phyllophaga lissopyge adults were captured primarily after or during a period of high precipitation (Pearson's r = 0.64364; n = 14) with the exception of January 2004 (usually the driest month in the area), when 8 males were captured after the field was heavily irrigated.
Phyllophaga obsoleta males were captured mainly during August and September of both years (9 adults in 2003 and 8 in 2004). Three P. obsoleta males were captured in December, January, and February (one each month) (Figure 3). The single male P. menetriesi was captured the second week of May.
Three species of Phyllophaga were captured during the study: P. lissopyge, P. menetriesi, and P. obsoleta. This information expands the geographical distribution of P. lissopyge to the country of Colombia and continent of South America. Bates (1888) described this species from two specimens collected at Volcán Chiriqui, Panama and Chontales, Nicaragua. Morón (2001) reported the occurrence of this species from between southern Costa Rica to western Panama. In 2003, Morón (2003) expanded the range of P. lissopyge from central Nicaragua to central Panama (Figure 1). Phyllophaga lissopyge is usually found on mountain slopes (620 to 2136 m elevation) with cloud forests, tropical rain forest, and coffee plantations (Morón 2003). Phyllophaga lissopyge may have arrived in Colombia through natural or human-mediated dispersal. Phyllophaga lissopyge could have spread from Panama to the north of Chocó department through the Darien Gap, and then through the same mountain system to Antioquia. Human-mediated dispersal is also likely, the commercial interchange between Colombia and Panama in this area being very intense and unregulated. Peck et al. (2001) suggested the same route of invasion for Prosapia simulans (Walker) (Homoptera: Cercopidae) from Central America to Colombia.
Phyllophaga lissopyge is a member of the genus Phyllophaga (sensu stricto), and is one of 865 species of Phyllophaga (s. lato) recorded from the New World (Evans and Smith 2009). However, based on phylogenetic analysis of external morphological and genitalic characteristics, Coca-Abia (2002) proposed the re-establishment of the genus Trichesthes (Erichson 1847) and removed 38 species from the Phyllophaga and into Trichesthes, including P. lissopyge and P. gigantea.
The flight patterns of P. lissopyge in Central America (Morón 2001, 2003) mirror our observations in Colombia, in that adults fly from February to November, with the largest flights occurring during March, April, and May.
The authors thank A. Gaigl and J. Montoya for their support, M. Londoño-Zuluaga (Corporación Colombiana de Investigación Agropecuaria, La Selva, Rionegro, Colombia) for care of the pheromone traps and insect captures, and M. Milagro Coca-Abia (Centro de Investigaciones y Tecnologías Agroalimentarias, Zaragoza, Spain) for confirming the identity of P. lissopyge. We also thank Matthew Petersen of Cornell University for assistance in preparing Figure 1. This project was funded in part by the German Federal Ministry of Economic Cooperation and Development through the project “Integrated Control of Subterranean Pests in South America” awarded to DCP.