Spittlebug damage on tropical grass and its impact in pasture-based beef production systems

Abstract

<p>Spittlebugs are the main pest of tropical pastures and Marandu palisade grass (<i>Urochloa brizantha</i> cv. Marandu) is the most representative cultivated pasture in the tropics. Our objective was to characterize Marandu palisade grass responses subjected to <i>Mahanarva</i> (Hemiptera: Cercopidae) attack and to estimate the losses in terms of beef production from pasture-based systems. A set of five experiments were carried out. Three consecutive years of monitoring showed that <i>Mahanarva</i> spittlebugs increased their abundance after first rains with three to four peaks throughout the wet season. A decrease of 66% on herbage yield was observed in the greenhouse trial, with an average decrease of 61% on pools of calcium, magnesium, phosphorus, sulfur, potassium, crude protein, neutral-detergent fiber and in vitro digestible dry matter of Marandu palisade grass. Results from field experiments corroborated with greenhouse trial showing decreases on herbage yield varying from 31 to 43% depending on level of fertilization and grazing severity of Marandu palisade grass. Finally, an unprecedented 154-ha field experiment indicated that <i>Mahanarva</i> decreases 74% the beef productivity (i.e. kg body weight ha^-1) of Nellore heifers grazing Marandu palisade grass.</p>