Erythrina speciosa Andrews (Fabales: Fabaceae) has multiple uses due to its medicinal properties, potential for recovering degraded areas, and excellent landscape effect, but insects that use this plant are poorly known. This paper reports, for the first time, the occurrence of Aethalion reticulatum (L., 1758) (Hemiptera: Aethalionidae) on E. speciosa seedlings in nurseries at Sacra Família do Tinguá, Municipality of Engenheiro Paulo de Frontin, Rio de Janeiro State, Brazil. Egg clutches of A. reticulatum were observed at the apex and on the median region of these seedlings, covered by a grayish brown substance, visually distinguished from the greenish color of the E. speciosa stem. Damage to this plant was characterized by hypertrophy and cracks at the apex of E. speciosa seedlings. Control measures for A. reticulatum, based on studies on other hosts, are presented.
The genus Erythrina (Fabales: Fabaceae) has more than 100 species in the tropical and subtropical regions of the world (Oliver-Bever 1981). Species of this genus are used by native populations to treat diseases and infections such as malaria, inflammation, bronchitis, insomnia, cough, and asthma (de Lima et al. 2006). Erythrina velutina Willd. is used to control epilepsy in northeastern Brazil (Dantas et al. 2004). The large quantity of alkaloids and flavonoids in these plants explains the medical use of Erythrina spp. (Cui et al. 2008; Ozawa et al. 2009).
Most species of the genus Erythrina are trees and shrubs, with few herbaceous ones, and therefore some of them are used in mixed plantations to restore degraded areas of permanent preservation (Lorenzi 1992; Zahawi 2008), besides having excellent landscape effect and producing shade during the summer. Erythrina speciosa Andrews (Fig. 1) occurs in Espírito Santo and Minas Gerais to Santa Catarina States in Brazil (Lorenzi 1992). This plant has typical inflorescence in a candelabra shape with red flowers (Fig. 2) that are attractive to many species of hummingbirds. Erythrina speciosa is a fast growing pioneer plant and adapted to damp places, such as swamps along rivers and coasts (Lorenzi 1992).
The morphology and phenology of E. speciosa are peculiar with the trunk full of thorns common to the genus, soft and durable wood, large leaves (usually in the form of rhombuses) that fall in the winter, and the tree having no foliage during the flowering period, which occurs in early spring (Lorenzi 1992).
Our objective was to record for the first time Aethalion reticulatum (Hemiptera: Aethalionidae) feeding on E. speciosa and describe its damage characteristics.
Materials and Methods
A leafhopper was found on E. speciosa seedlings in nurseries of Sacra Família do Tinguá, Municipality of Engenheiro Paulo de Frontin, Rio de Janeiro State, Brazil, showing the need of describing its damage characteristics. Seedlings of this plant that were 4 mo old and 20 cm high were inspected daily during Jan and Feb 2009. Specimens of this leafhopper were collected, kept in 70% alcohol, and sent to Dr. Gabriel Simões de Andrade (Unioeste-PR) for identification.
The Municipality of Engenheiro Paulo de Frontin in Rio de Janeiro State, Brazil, is located at 22°32'59" S, 43°40'42" W at 395 m altitude with a typical tropical climate. The Atlantic rainforest vegetation is abundant in this region with almost half of the territory of the Sacra Família do Tinguá with this kind of vegetation. The occurrence and damage characterization of A. reticulatum were observed on seedlings from a nursery of the Non-Governmental Organization “Floresta Brasil,” which leads a regional project of reforestation to recover degraded areas.
Photos of adults and damage by leafhoppers were obtained in macro mode with a digital camera (model DSC-W70, Sony Cyber-Shot, 7.2 megapixels), and adults of this leafhopper were held in the Regional Museum of Entomology of the Department of Animal Biology, Federal University of Viçosa in Viçosa, Minas Gerais State, Brazil.
The leafhopper was identified as Aethalion reticulatum (L., 1758) (Hemiptera: Aethalionidae). The adult had its rostrum emerging from the bottom face of its head, short setaceous antennae, and membranous wings, which, in general, characterizes the individuals of the suborder Auchenorrhyncha. The Hemipteran order is currently divided into 4 suborders; among them, the Auchenorrhyncha suborder, which Araújo et al. (2010) considered to be paraphyletic, while Cryan & Urban (2011) presented molecular evidence that suggested the suborder to be monophyletic. Aethalion reticulatum adults were approximately 10 mm long with rusty-brown color and protruding ribs of the wings and greenish tones (Fig. 3). The posterior tibia did not have thorns, which characterizes the family Aethalionidae.
Aethalion reticulatum infested most of the observed E. speciosa seedlings and laid their eggs at the apex and at median parts of seedlings surrounded by a gray-brown substance, visually different from the green color of the stem of this plant (Fig. 4). Nymphs and adults (winged) of A. reticulatum remained clustered near the apex or at the median parts of E. speciosa plants and were associated with ants of the genus Camponotus (Hymenoptera: Formicidae) (Fig. 5). The main damage symptoms caused by A. reticulatum were hypertrophy and cracks at the apex of E. speciosa seedlings (Fig. 3). No natural enemy was found associated with A. reticulatum eggs, nymphs, or adults in the field.
We here described for the first time the leafhopper A. reticulatum infesting and damaging E. speciosa seedlings in nurseries at Sacra Família do Tinguá, Municipality of Engenheiro Paulo de Frontin, Rio de Janeiro State, Brazil. This species has been reported causing direct and indirect damage on a broad range of tropical fruit plants such as cashew, cherry, citrus, fig, grape, jackfruit, mango, plum, and tamarind (Hickel et al. 2001; Soria & Dal Conte 2005), on medicinal plants such as figatil (Vernonia condensata Baker; Asterales: Asteraceae) (Menezes et al. 2013) and clove basil (Ocimum gratissimum L.; Lamiales: Lamiaceae) (Rando & Lima 2010), and on exotic plants of agriculture and forest importance (Santana et al. 2005). This pest sucks the sap from the stalk of the fruits leading to atrophy and losses before harvest, as reported for mango, Mangifera indica L. (Sapindales: Anarcadiaceae), in Mexico (Waite 2002). The egg clutches of A. reticulatum are often confused with the bark of fruit plants where the gray-brown substance covering the eggs serves to camouflage them and protect against natural enemies (Rando & Lima 2010). The females of this insect lay up to 100 eggs on the branches or stems of the fruits of host plants (Rando & Lima 2010).
The herein observed association between A. reticulatum and Camponotus ants was previously reported for this leafhopper on Bauhinia forficata Link (Fabales: Fabaceae) (Fowler 1992) with mutual benefit between the two species. The leafhopper gets protection from the ants, while the ants receive rich carbohydrates, such as glucose, fructose, and sucrose, and free amino acids, lipids, starch, minerals, and vitamin B in a mixture named honeydew (Way 1963; Brown 1976; Völkl et al. 1999; Goussain et al. 2005). Adults of A. reticulatum can also be associated with stingless bees of the genus Trigona (Hymenoptera: Apidae) without necessarily resulting in dependence (Vieira et al. 2007; Baronio et al. 2012).
The most characteristic damage symptoms caused by A. reticulatum were hypertrophy and cracks at the apex of E. speciosa seedlings. This insect lives in colonies whose many individuals inject a large quantity of phytotoxic saliva into the plant and thereby contribute to premature aging of the stem. In general, the damage caused by A. reticulatum in E. speciosa was similar to that caused on fruit plants by this insect (Nascimento & Carvalho 1998).
The rapid lateral movement of A. reticulatum nymphs and adults hinders their mechanical control on E. speciosa seedlings as suggested on grapevines, where this species is considered a secondary pest (Soria & Dal Conte 2005). Although we did not detect any natural enemies associated with A. reticulatum, several have been reported. Among them, the egg parasitoids Lymaenon aethalionis (Oglobin) (Hymenoptera: Myrmaridae), Abbelloides marquesi Brèthes, Latromerella sp., and Uscanopis sp. (Hymenoptera: Trichogrammatidae) and the nymph parasitoid Mycrotherys claripennis Compère (Hymenoptera: Encyrtidae) are the main natural enemies of A. reticulatum (Silva et al. 1968). The efficacy of these natural enemies in the field needs to be better studied, including the ectoparasite Aulacothrips dictyotus Hood (Heterothripidae), which was found under the wings of adults of this leafhopper (Izzo et al. 2002). Aqueous extracts of Piper aduncum L. (Piperales: Piperaceae) leaves showed insecticidal activity on Aethalion sp. adults and therefore may represent an alternative to control this insect (Silva et al. 2007).
Aethalion reticulatum infested most of the E. speciosa seedlings and reduced their growth. This confirms the high adaptability of this aethalionid leafhopper on a broad range of host plants in Brazil. The biological performance of A. reticulatum on other species of the genus Erythrina with economical importance, and effective measures to control this pest should be investigated. To our knowledge, this is the first record of A. reticulatum feeding on E. speciosa seedlings, with a characterization of the damage it causes.
We thank Gabriel Simões de Andrade (Unioeste-PR) for identifying Aethalion reticulatum, and we acknowledge “Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)” and “Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)” for financial support.