Baru (Dipteryx alata Vogel, Fabaceae) as new host of the treehopper Aetalion reticulatum (Linnaeus, 1767) (Hemiptera: Aetalionidae)

The treehopper Aetalion reticulatum (Linnaeus, 1767) (Hemiptera: Aetalionidae) was found infesting three baru trees (Dipteryx alata Vogel) in Brasilia, Distrito Federal, Brazil. Aetalium reticulatum is considered an important pest and has been reported to damage various agricultural and forest crops. However, this is the first report of this insect in baru, a native tree species from the Brazilian Cerrado, thus expanding the insect’s known host range.

Baru (Dipteryx alata Vogel, Fabaceae) is a native forest species from the Brazilian Cerrado, occurring the Central-West, North, Northeast, and Southeast of Brazil (Lima & Lima 2019). It can reach up to 25 meters in height, with average of 15 meters (Sano et al. 2016). The tree is considered a multi-use species, in which almost all parts of the plant can be used for different purposes, such as food (bark and nut), medicine (bark, trunk, and leaves), and lumber (Sano et al. 2016). Thus, baru can be an alternative source of income for local populations, especially baru nuts.
Some insects have been reported to damage fruits of baru seeds, especially Coleoptera and Lepidoptera larvae (Almeida et al. 1998).
To date, the Hemiptera had not been reported as attacking D. alata. Therefore, this paper is the first report about the occurrence of a treehopper harmful to the baru and describes the damage constated on three trees located in Brasilia, Brazil.
In January and February 2017, treehoppers were observed infesting three baru trees in different parts of Brasilia, Distrito Federal, Brazil (two at coordinates 15°43'49.2"S, 47°54'00.3"W and one at coordinate 15°44'32.7"S, 47°53'05.0"W). The trees analyzed were mature, about five meters tall, and produced fruit regularly. Insect samples were stored in Falcon® tubes, containing 70% alcohol, and taken to the Entomopathogenic Bacteria Laboratory at Embrapa Genetic Resources and Biotechnology for identification with the aid of stereoscopic microscope. The specimens examined were morphologically/ morphometrically compared with the literature (Santos et al. 2015, Zanuncio et al. 2015 to determine the species, and the damage caused by the colonies were characterized and photographed. Treehoppers were identified as Aetalion reticulatum (Linnaeus, 1767) (Hemiptera: Aetalionidae). The insects were observed mainly in the youngest buds and branches of the plants, as well as the peduncles that support the fruits. However, colonies were also observed in more lignified tissues. The main damage symptoms caused by A. reticulatum on the trees were deformation of the stem and the apical bud, and a tree had cracks at the apex.
In addition to the treehoppers, bees of the species Trigona spinipes (Fabricius, 1793) (Hymenoptera: Apidae) were in mutualistic association with the insect (Fig. 1), in which the bee defends the treehopper from possible predators in exchange for sugary honeydew secretions (Castro 1975). This interaction between the two insect species is already known to science and is apparently not mandatory but may further impair fruit production (Vieira et al. 2007). All stages of insect development (eggs, nymphs, and adults) were found in the three surveyed baru trees, indicating that A. reticulatum can develop and reproduce feeding exclusively on D. alata. This treehopper feeds on its hosts by the continuous suction of sap, which impairs plant development and the development of new shoots and fruits (Gallo et al. 2002). Some leaves and new shoots of the analyzed three trees presented symptoms of sooty mold, with the formation of a layer of black fungal mycelium, especially on leaves that were near or below the insect colonies. The constant feeding of A. reticulatum favors the appearance of the fungus that causes sooty molds (Capnodium sp., Capnodiaceae) on the trunk and leaves, which hinders photosynthesis (Chomnunti et al. 2014).
The association of this treehopper with native plants of the Brazilian Cerrado is not well known, and so far, baru had not been reported as an alternative host of this insect. Thus, this paper records the first occurrence of A. reticulatum in D. alata.

Author's Contributions
MTC: Performed the material collection and analysis; wrote the manuscript. SCLM: Performed the material collection and analysis; wrote the manuscript. RGM: Contributed to the interpretation of the results.