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

Abstract

Spittlebugs are the main pest of tropical pastures and Marandu palisade grass (Urochloa brizantha cv. Marandu) is the most representative cultivated pasture in the tropics. Our objective was to characterize Marandu palisade grass responses subjected to Mahanarva (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 Mahanarva 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 Mahanarva decreases 74% the beef productivity (i.e. kg body weight ha −1) of Nellore heifers grazing Marandu palisade grass. Brazil has the largest commercial beef cattle herd and is one of the top beef exporters in the world 1. Brazilian beef represents 20% of all global beef trading and, together with other agricultural commodities, it sums to about 21% of gross domestic product in Brazil 2. Beef cattle production in Brazil is characterized by pasture-based systems of which almost 90% of the cattle slaughtered comes from 3. However, despite highly representative, pasture-based livestock systems are extensive and conducted with low technology inputs resulting in low stocking rates (SR) and animal performance (i.e. average daily gain, ADG). Studies have reported beef production greater than 1,500 kg of body weight (BW) ha year −1 whilst the Brazilian average is much lower at about 150 kg BW ha year −14. Many factors stand out as key drivers for this poor productivity, among them: inadequate grazing management strategies, low soil fertility, and pest damage 5. The 215 million head of cattle in Brazil occupy approximately 160 million hectares composed by 70% of cultivated pasture species and 30% of native grasslands 6,7. Marandu palisade grass {Brachiaria brizantha (Hochst. ex A. Rich.) R. D. Webster [syn. Urochloa brizantha (A. Rich.) Stapf]} is the most representative of the cultivated pasture species, grown in about 50 million hectares in the country 8. It was launched by Embrapa in 1984 as an alternative to signal grass (Brachiaria decumbens cv. Basilisk, syn. Urochloa decumbens Stapf R.D. Webster) owing to its higher herbage yield and, mainly because of its resistance to "pasture spittlebugs" such as Notozulia entreriana (Berg, 1879), Deois flavopicta (Stål, 1854) and Deois schach (Fabricius, 1787) (Hemiptera: Cercopidae) 9. However, from the mid-1990s, spittlebugs from the genus Mahanarva have been r...

Spittlebugs (Hemiptera: Cercopidae): Integrated Pest Management on Gramineous Crops in the Neotropical Ecozone

“…Hence, milk and meat production are affected even in low infestations of spittlebugs in forages cultivation. Congio et al (2020) showed that Mahanarva sp. can decrease beef productivity up to 74% and herbage yield varying from 31 to 43% (depending on level of fertilization and grazing severity of Marandú).…”

Lignin, glutathione and kinases play important roles inPaspalum regnelliidefense against spittlebug (Mahanarva spectabilis) attack

“…These insects cause global economic losses of more than US$ 2 billion a year (Thompson, 2004) because of quantitative and qualitative damage that reduces the dry matter volume and decreases nutritional capacity (Congio et al ., 2012). In Brazil, the genus Mahanarva became highly reported as an agricultural pest of forage grasses and sugarcane in the 1990s (Congio et al ., 2020), with Mahanarva spectabilis (Distant, 1909) being responsible for limiting livestock production of beef and milk (Auad et al ., 2007).…”