Quesada gigas, Olivier

Zanuncio, José Cola, Pereira, Fabrício Fagundes, Zanuncio, Teresinha Vinha, Martinelli, Nilza Maria, Pinon, Tobias Baruc Moreira & Guimarães, Edylene Marota, 2004, Occurrence of Quesada gigas on Schizolobium amazonicum trees in Maranhão and Pará States, Brazil, Pesquisa Agropecuária Brasileira 39 (9), pp. 943-945 : 943-945

Q. gigas

presents the largest geographical distribution and it is the better studied species of the ten most important of this group in the American continent. Besides, it is the only species which has been registered in North America, the Antillas and in most Brazilian States where coffee is produced ( Martinelli & Zucchi, 1987).

Plants attacked by cicada nymphs present chlorosis of leaves in branch extremities, losses of leaves, nude branches, leaves only in the apexes, low production and death of plants ( Reis et al., 2002).

An infestation of a cicada species was registered in November 2002 in a reforested area with Schizolobium amazonicum (Huber) Ducken ( Fabales : Fabaceae ) plants in Itinga, Maranhão Stateand Paragominas, Pará State with severe damage to trees in 15 hectares. Immobile nymphs and adults ( Figure 1 ) of this insect were observed on trunks of trees as well as circular holes ( Figure 2A ) in the soil around trunks of S. amazonicum trees, which are exit holes of movable nymphs of cicadas. After leaving the soil, these nymphs turntoanimmobilestageandafter afinalmolting theadult emerges.Suchholesdemonstratedthatthesenymphswere attacking S. amazonicum roots ( Figure 1C ), leading to a fall of leaves and reduction on growth ( Figure 2B ). This damage is similar to that observed in coffee trees with emphasized symptoms during periods of water deficit and withinsignificant blooming, lowfruit productionand tree death if this pest is not controlled ( Reis et al., 2002).

Adults cicadas were manually collected in trunks of S. amazonicum and seemedto belongto a single species. Movable nymphs of this insect were collected with traps ( Figure 2C ) made of a two-meter-diameter cloth screen around S. amazonicum trees when they left the soil throughexit holes.Adults of thiscicada were killed, fixed inalcohol 70% andsent to Universidade Estadual Paulista for identification.

Insects were identified as Q. gigas and they represent the first report of this species on S. amazonicum in Itinga, Maranhão Stateand Paragominas, Pará State.

The substitution of native hosts by monoculture in extensive areas and cultivation during long periods can be one of the reasons which explains biological unbalance presented by some insects such as cicadas especially with species of the family Cicadidae . These insects are adapting to the new conditions where they can obtain food from cultivated plants ( Martinelli & Zucchi, 1997b).

The fact that studies on cicadas have been usually restricted to species associated to coffee trees ( Coffea spp. ) in Brazil shows the necessityof developing researches to identify the occurrence and to minimize damages by these insects to other cultures. The potential of damage of Q. gigas in S. amazonicum needs to be considered because the area reforested with this plant is over 20,000 hectars in the States of Maranhão and Pará and damages to trees attacked by this insect were very severe. It also shows the necessity of studies on the efficiency of insecticides to be used in forest areas tocontrolthis pest inemergence situations, giving priority to low toxicityproductsin orderto reduce environmental impacts of these operations.

Figures

Figure 1. Nymph (A) and adult (B) of Quesada gigas on a trunk of Schizolobium amazonicum and nymph (C) of this insect feeding on root of this plant.

Figure 2. Exit holes of Quesada gigas (A), plants of Schizolobium amazonicum with symptoms of attack by this insect (B) and trap to capture nymphs (C).