Brachiaria ruziziensisResponses to Different Fertilization Doses and to the Attack ofMahanarva spectabilis(Hemiptera: Cercopidae) Nymphs and Adults

Abstract

Cropping practices are necessary in order to help reduce the population of pest insect, such as the induction of resistance through fertilization. Therefore, this study aimed to assess alterations on the production and quality of Brachiaria ruziziensis when receiving the fertilization composed by the macronutrients NPK and/or exposed to the attack of Mahanarva spectabilis nymphs and adults. B. ruziziensis plants were fertilized according to the recommendation (R), half of the recommended fertilization (H), or non-fertilization (C). They were also exposed to different M. spectabilis nymph and adult densities. The damage, regrowth, and bromatological components were evaluated. The fertilization treatment promoted a higher M. spectabilis nymph survival on B. ruziziensis; however, it reduced the damage caused by the forage exposed to nymphs and adults of pest insect, and it did not alter the quality of the signal grass. Moreover, the fertilization treatment enabled forage recovery, even when exposed to 5 nymphs or 10 spittlebug adults.

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

“…Despite this, the main injury to infested plants is caused by adult spittlebugs. For successful feeding, adults first introduce the stylet into the plant tissue, and this action, combined with salivary enzymes, breaks down the cell walls and causes death of the leaf tissue, thereby reducing the chlorophyll content and regrowth capability of the plant . This effect makes this insect one of the factors limiting extensive raising of livestock in Brazil.…”

“…The injury comprises yellowing, chlorotic stripes and even necrosis of the plants . According to Resende et al ., the increase in injury tends to be higher with an increased density of spittlebug adults. Although injury caused by feeding of spittlebug nymphs is less important and less severe than adult‐caused injury, the current data demonstrate that M. spectabilis may be aggressive even from the nymphal phase, and can cause relevant injuries and restrict the development of forages.…”

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

“…(Fonseca et al, 2016). 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.)…”

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

“…Several authors linked a decrease in regrowth capacity in forage species after 30 days of pruning to the activities of spittlebugs . This reduction occurs due to the large amount of sap sucked by the nymphs, which causes water imbalance and depletion of soluble carbohydrates used in the plant growth process, impairing forage grass persistence capacity and diminishing its regrowth ability.…”