Impact of Tetranychus ogmophallos (Acari: Tetranychidae) on different phenological stages of peanuts

ABSTRACT Peanut red mite, or Tetranychus ogmophallos Ferreira and Flechtmann, is considered the major emerging pest of peanut in Brazil. Its impact on peanut farming is still unknown but can be harmful. Thus, it is essential to understand how this mite influences peanut for a successful pest management program. This study aimed to investigate the impact of T. ogmophallos on peanut plants at different growth stages in order to clarify whether or not it is worth controlling this pest throughout the peanut growing season. For that, four experiments were carried out in a greenhouse to evaluate the impact of T. ogmophallos infestation on peanut plants at different phenological stages. Results showed that peanut seedlings of up to 60 days emergence and infested with red mite did not complete the reproductive cycle. In addition, infestation at 90 days after seedling emergence (late season) led to considerable yield reduction. As a result, we may infer that infestation can significantly peanut yield, regardless of plant phenological stage. Thus, controlling this emerging pest is necessary even if infestations occur in the final stages of plant development. The adopted level of infestation is above the economic threshold given the importance of the impact on growth and yield of these plants. Because of this, establishing an economic threshold level at different plant developmental stage is crucial to determine when control measures should be taken.

摘要 花生红螨（Tetranychus ogmophallos Ferreira and Flechtmann）被认为是巴西花生生产中新兴的主要害虫。目前其对花生种植的影响尚不明确，但潜在危害不容忽视。明确该螨对不同生育阶段花生植株的作用，对制定高效的害虫防控方案至关重要。本研究旨在探究T. ogmophallos对不同物候期花生植株的影响，以厘清花生全生育期是否需要对该害虫开展防控工作。为此，本研究在温室中共开展4组试验，评估不同物候期花生植株受T. ogmophallos侵染后的影响。结果表明：出苗后60天内的花生幼苗若受红螨侵染，则无法完成生殖周期；此外，出苗后90天（生育后期）的侵染会造成显著的产量损失。由此可推断，无论花生处于何种物候阶段，该螨的侵染均会显著降低花生产量。因此，即便该新兴害虫在植株发育后期发生，也有必要实施防控措施。结合该螨对花生生长及产量的严重危害，本研究所采用的侵染水平已超出经济阈值。据此，针对不同植株发育阶段制定专属经济阈值，对确定防控措施的实施时机具有关键意义。