The Damage Capacity of Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae) Adults on Brachiaria ruziziensis Pasture

Abstract

The aim of this study was to determine the damage caused by adult Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae) on Brachiaria ruziziensis (Germain & Evard) under field conditions. A total of 0, 4, 8, 12, or 16 M. spectabilis adults per plot were maintained for 6 days. Thereafter, the insects were removed from the plant, and the following parameters were evaluated: chlorophyll content, damage score, dry as well as fresh weights, percentage of shoots' dry matter, and the forage's ability to regrow. The chlorophyll content was significantly reduced; the damage score and percentage of dry matter in plants increased depending on the increased insect infestation density after 6 days of exposure. In contrast, no change was observed on the B. ruziziensis fresh and dry weights as well as the regrowth capacity depending on the M. spectabilis infestation densities. Attacks by 8 adult M. spectabilis per clump of B. ruziziensis with an average of 80 tillers for 6 days were sufficient to reduce the chlorophyll content and the functional plant loss index. This density can be a reference for spittlebug integrated management in Brachiaria.

Tolerance to nymphs and adults of Mahanarva spectabilis (Hemiptera: Cercopidae) by forage plants in fertilized soils

“…Injuries caused by spittlebug feeding also result in the early drying of plants, a decrease in fresh weight and consequently, an increase in the percentage of dry matter . In the case of RUZ 2, there was no percentage increase for any bioassay, which differed from the results of Resende et al . indicating that the intensity and infestation period were probably insufficient to cause any increase in this factor.…”

Influence of pastoral systems on Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae) and the entomopathogen Metarhizium anisopliae (Metsch.) Sorokin

“…Both nymphs and adults damage the host plant by sucking sap and injecting toxins which induce plant tissue yellowing and reduce photosynthetic rates (Byers e Wells 1966;Resende et al, 2013;Aguiar et al, 2014). Resende et al, 2013) Application of the entomopathogenic fungus Metarhizium anisopliae (Metsch.) (Hypocreales: Clavicipitaceae) to control spittlebugs in pasture and sugarcane are usual in Brazil (Hernándéz-Dominguez et al, 2016).…”

Do silicon and nitric oxide induce resistance to Mahanarva spectabilis (Hemiptera: Cercopidae) in forage grasses?

“…According to Dinardo‐Miranda et al , chlorophyll reduction may negatively affect plant photosynthetic capacity and crop production. As several authors have reported, damage increases in proportion to increased spittlebug density . All forage grass plants infested at any density showed different intensities of the symptoms typical of spittlebug damage, which includes yellowing, chlorotic stripes and plant death …”