Universidade Federal de Lavras, Caixa postal 3037, Cep 37200000, Lavras, MG, Brazil.
Embrapa Gado de Leite, Av. Eugênio do Nascimento, 610, CEP 36038-330, Juiz de Fora, MG, Brazil.
Sci Rep. 2019 Jul 16;9(1):10284. doi: 10.1038/s41598-019-46693-9.
Several herbivorous insects utilize plant chemical cues to identify hosts for feeding. The role of smell in host plant detection by Mahanarva spectabilis (Distant) remains largely unknown. In this study, assays were applied to assess M. spectabilis olfactory responses to forage grasses (Pennisetum purpureum cvs. Roxo Botucatu and Pioneiro; Panicum maximum cvs. Makueni and Tanzânia; Hyparrhenia rufa cv. Jaraguá; Melinis minutiflora; Cynodon dactylon cv. Tifton; Brachiaria brizantha cv. Marandú; and Brachiaria decumbens cv. Basilisk). Bioassays were performed using a Y-olfactometer to evaluate the behavior of adult M. spectabilis to forage damaged and undamaged by insects. M. spectabilis preferred volatiles of undamaged Basilisk and Pioneiro. Repellent behavior by M. spectabilis to cospecifics was recorded for plant volatiles from damaged Marandú. The mixture of volatiles from undamaged forage grasses differed from that of forage grasses damaged by insects. Forage grasses showed a greater diversity of compounds after damage, including menthone, eucalyptol and camphor, which are compounds likely to cause loss of attractiveness or repellence. Our results demonstrate that M. spectabilis employs plant chemical cues in its choice of hosts. This fact may contribute to strategies of integrated management against this pest.
几种草食性昆虫利用植物的化学线索来识别觅食的宿主。大草蛉（Mahanarva spectabilis）利用嗅觉来识别其宿主植物的作用在很大程度上尚不清楚。在这项研究中，应用了测定法来评估大草蛉对饲料草（Roxo Botucatu 和 Pioneiro 品系的杂交狼尾草、Makueni 和 Tanzânia 品系的象草、Jaraguá 品系的鲁非草、细茎冰草、Tifton 品系的狗牙根、Marandú 品系的杂交臂形草和 Basilisk 品系的匍匐臂形草）的嗅觉反应。使用 Y-嗅觉计进行生物测定，以评估成年大草蛉对昆虫损伤和未损伤饲料的行为。大草蛉更喜欢 Basilisk 和 Pioneiro 未受损的挥发物。大草蛉对受损的 Marandú 植物挥发物表现出同种相斥的回避行为。未受损饲料草的挥发混合物与受昆虫损伤的饲料草的挥发混合物不同。受损伤的饲料草表现出更多种类的化合物，包括薄荷酮、桉树脑和樟脑，这些化合物可能导致吸引力或驱避性丧失。我们的结果表明，大草蛉在选择宿主时利用植物的化学线索。这一事实可能有助于制定针对这种害虫的综合管理策略。
