The family Tettigoniidae is associated with grassland damage in several countries, but there are few reports of tettigoniids causing damage to other crops. Specimens of katydids were found damaging banana fruits in Brazil. A survey of their occurrence was conducted, and the damage to banana fruits was quantified. Specimens were identified as Meroncidius intermedius Brunner Von Wattenwyl (Orthoptera: Tettigoniidae). This is the first report of damage caused by this species to an economic crop, and to banana. Symptoms and frequency of damage to banana crops, and behavior of M. intermedius, are discussed.
Banana (Musa spp.) (Musaceae) is one of the most important fruits worldwide due to its relevance as a basic nutritional food source and its economic importance to several countries, particularly developing countries (Fioravanço 2003). In Brazil, this crop is cultivated principally by smallholders because it can be cultivated on a diversity of soils and under various climatic conditions. In addition, this crop requires low investment and labor for planting and maintenance and is easily commercialized. This crop is cultivated in tropical and subtropical regions of Brazil, and 17,000 farms may be found cultivating bananas on more than 25,000 ha (Espírito Santo 2012; IBGE 2016).
The principal pest problems of banana in Brazil are Sigatoka leaf spot disease Mycosphaerella musicola R. Leach ex J. L. Mulder (Mycosphaerellaceae); black leaf streak disease Mycosphaerella fijiensis M. Morelet (Mycosphaerellaceae); Fusarium wilt Fusarium oxysporum f. cubense (E. F. Sm.) W. C. Snyder & H. N. Hansen (Nectriaceae); and banana root borer, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) (Borges et al. 2006). Katydids (Orthoptera: Tettigoniidae) such as Idiarthron atrispinum (Stål) (Orthoptera: Tettigoniidae) (Maes 2004) and Idiarthron subquadratum Saussure & Pictet (Orthoptera: Tettigoniidae) have been reported using banana trees only as shelter (Barrera et al. 2002) but no damage has been found previously. Species of this family have crepuscular habits and long developmental periods, with 5 to 6 instars (Barrera et al. 2003). Knowledge of the biology and species distribution of Tettigoniidae in South America is limited (Chamorro-Rengifo et al. 2011; Fialho et al. 2014), but katydids are infrequently associated with crop damage (Barrera et al. 2002; Foster et al. 2004; Mohammadbeigi & Port 2013).
Damage caused by katydids was observed on fruits of commercial crops of the banana cultivar Pacovan (Musa cv. Pacovan, genotype AAB) in several plantations in Espírito Santo State, Brazil. Nymphs and adults of this katydid were collected, preserved in 70% alcohol and sent to the Laboratory of Systematics and Biology of Coleoptera, Department of Animal Biology of the Federal University of Viçosa, Brazil. A key to species identification (Beier 1960) with additional information from Orthoptera Species File Online (Eades et al. 2017) were used to identify Meroncidius intermedius Brunner Von Wattenwyl (Orthoptera: Tettigoniidae) as the species associated with banana. Losses were measured in an area of 25 ha in the municipality of Alfredo Chaves (20.5115°S, 40.7743°W), Espírito Santo State, Brazil, from Oct 2012 to Sep 2013. Symptoms of this pest were evaluated after the harvest of banana fruits. In addition, 10 bamboo traps with attractive food (corn meal + sugar 5% + water) (Gallo et al. 2002) were used from May to Jul to capture nymphs and adults.
Damage caused by M. intermedius was due to the feeding of adults (Fig. 1a) and nymphs (Fig. 1b) observed on the fruit peel (Fig. 1c); however, they also may eat the fruit pulp, and in some cases the banana bunch is severely damaged (Fig. 1d). These symptoms of attack reduced the commercial value of the fruits.
These insects were first detected occurring in banana plantations in May (autumn), with outbreaks observed from the late winter (Aug) to the beginning of spring (Sep), and a decrease occurring in late spring (Nov) to mid-autumn (Apr). Immature specimens were most frequently observed from May to Sep. Nymphs and adults were found sheltered in bunches, below the first leaf that covered the peduncle, or between leaves, during the day. Feeding occurred at night. This behavior is similar to that of other katydid species (Barrera et al. 2002) in which adults were usually found alone, and instars 2 and 3 aggregated in small groups (Foster et al. 2004). Meroncidius sp. also has been observed attacking fruits and inflorescence of coconut in Brazil. The female of this genus has a long lance-shaped ovipositor used to open cracks in the leaf rachis, peduncle of bunches, floral branches, and fruits, where it lays eggs (Ferreira et al. 2013).
This is the first report of M. intermedius causing economic losses. This species was first reported in Brazil in 1950 (Ferreira & Mesa 2010), but no damage had previously been reported in economically important crops. Females of this katydid species use their ovipositor to open longitudinal slits in branches, where they lay eggs (Costa Lima 1938); however, few eggs were found in banana trees. Estimated fruit losses varied from 10 to 40%, depending on the season (Fig. 2) and the distance from the native Atlantic rainforest remnants. The dispersal behavior of M. intermedius may explain the greater amount of damage observed on the edges of the banana plantations, close to the forest remnants. This finding may indicate that these insects dwell principally in the native vegetation but sometimes relocate and feed on the banana crop.
The bamboo traps did not capture specimens of M. intermedius during the evaluation period. However, bamboo traps were previously found to be more attractive than banana to the katydid I. subquadratum (Barrera et al. 2002). It is possible that M. intermedius finds shelter and food in banana plants, thereby leading to trap inefficiency. Further studies of its behavior and ecology are needed to understand its damage potential and to facilitate the development of nonchemical management techniques.
We thank Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural (INCAPER) and Fundação de Amparo à Pesquisa e Inovação do Espírito Santo (FAPES) for financial support.