Differential defense responses of tropical grasses to Mahanarva spectabilis (Hemiptera: Cercopidae) infestation

Abstract

The spittlebugs Mahanarva spectabilis economically challenges cattle production of neotropical regions, due to its voracious feeding on tropical grasses.Here, we evaluated biochemical responses of the interaction between M. spectabilis and the widely cultivated tropical grasses Brachiaria spp. (i.e., brizantha and decumbens) and elephant grasses (cvs. Roxo de Botucatu and Pioneiro), regarding lipoxygenases, protease inhibitors, phytohormones, and proteolytic activities in the midgut of M.spectabilis. The M. spectabilis-infested grasses increased lipoxygenases activity, except for cv. Pioneiro. The levels of the phytohormones jasmonic and abscisic acids were similarly low in all genotypes and increased under herbivory. Furthermore, salicylic acid concentration was constitutively higher in Brachiaria sp., increasing only in spittlebuginfested B. decumbens. M. spectabilis infestations did not induce increases of protease inhibitors in any forage grass type. The trypsin activity remained unaltered, and the total proteolytic activity increased only in B. decumbens-fed insects. Our fi ndings revealed that most forage grasses exposed to spittlebugs activate the lipoxygenases pathway, resulting in increased abscisic and jasmonic acids. However, greater amounts of these hormones do not induce protease inhibitory activity in response to spittlebug attack. This knowledge certainly helps to guide future projects aiming at reducing the impact of spittlebugs on forage production.

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

“…An interesting GO found in BGP 248 is the salicylic acid catabolic process. It is usually linked to the stress response, but in this case, it alone does not seem to play a large role in spittlebug defense due to compounds in M. spectabilis saliva that may impede its signaling, although in some species (such as U. decumbens ), it has been identified after infection (Barros et al ., 2021). In addition, it is common for plants to focus their energy expenditure on resisting herbivores, increasing the production of resistance mechanisms to the detriment of their development (Divekar et al ., 2022); this does not occur in the BGP 248 genotype, which continues to produce root growth and seed ripening, for example.…”

“…SA, which is typically associated with the stress response, may undergo degradation because it may not play a prominent role in defense against spittlebugs. The presence of compounds in M. spectabilis saliva may hinder SA signaling, although its detection has been reported in susceptible species such as U. decumbens postinfection (Barros et al, 2021).…”

“…SA, which is typically associated with the stress response, may undergo degradation because it may not play a prominent role in defense against spittlebugs. The presence of compounds in M. spectabilis saliva may hinder SA signaling, although its detection has been reported in susceptible species such as U. decumbens postinfection (Barros et al, 2021). Furthermore, plants often prioritize resource allocation toward defense mechanisms in response to herbivore pressure, potentially at the expense of growth and development (Divekar et al, 2022).…”

Capim Xaraés Submetido a Inoculação E Coinoculação Com Rizobactéria Promotora Do Crescimento De Plantas E Fungo Micorrízico Arbuscular

“…Empregar técnicas voltadas à abordagem atual de produção agrícola, priorizando a sustentabilidade ambiental e animal, caracterizam redução no aporte de fertilizantes químicos e custo de produção, proporcionando produtividade com reduzido impacto ambiental. A espécie Urochloa brizantha (sinonímia Brachiaria brizantha) é uma gramínea que apresenta alta resistência a cigarrinhas (4) e ao fungo de solo Rhizoctonia (5) ; de elevado valor nutritivo (6) ; adaptada a solos de baixa fertilidade 326 326…”