Carmo-Sousa Michele, Garcia Rafael Brandão, Wulff Nelson Arno, Fereres Alberto, Miranda Marcelo Pedreira
Fund for Citrus Protection, FUNDECITRUS, Araraquara, São Paulo 14807040, Brazil.
Spanish National Research Council, CSIC, 28006 Madrid, Spain.
Insects. 2020 May 16;11(5):314. doi: 10.3390/insects11050314.
Liberibacter asiaticus (Las) is a phloem-limited bacterium that is associated with the Huanglongbing (HLB) disease of citrus and transmitted by the psyllid, . There are no curative methods to control HLB and the prevention of new infections is essential for HLB management. Therefore, the objective of our study was to determine the effects of systemic insecticides, such as the neonicotinoids imidacloprid, thiamethoxam, and a mixture of thiamethoxam and chlorantraniliprole (diamide) on the probing behavior of Las-infected and their effect on Las transmission. The electrical penetration graph (EPG-DC) technique was used to monitor the stylet penetration activities of Las-infected on sweet orange [ (L.) Osbeck] 'Valencia' treated with systemic insecticides. Systemic insecticides disrupted the probing behavior of Las-infected , in a way that affected Las transmission efficiency, particularly by negatively affecting the stylet activities related to the phloem phase. All insecticides reduced (by 57-73%) the proportion of psyllids that exhibited sustainable phloem ingestion (waveform E2 > 10 min), with significant differences observed on plants treated with thiamethoxam and thiamethoxam + chlorantraniliprole. The transmission rate of Las with high inoculum pressure (five Las-infected per plant and a seven-day inoculation access period) to untreated control plants was 93%. In contrast, Las transmission was reduced to 38.8% when test plants were protected by systemic insecticides. Our results indicated that all insecticides tested presented a potential to reduce Las inoculation by an average of 59%; therefore, these insecticides can be used to reduce the spread of HLB.
亚洲韧皮杆菌（Las）是一种局限于韧皮部的细菌，与柑橘黄龙病（HLB）有关，并由木虱传播。目前尚无治愈HLB的方法，预防新的感染对于HLB的管理至关重要。因此，我们研究的目的是确定系统性杀虫剂，如新烟碱类杀虫剂吡虫啉、噻虫嗪以及噻虫嗪与氯虫苯甲酰胺（双酰胺类）的混合物，对感染Las的木虱取食行为的影响及其对Las传播的作用。采用直流电子穿透图（EPG-DC）技术监测经系统性杀虫剂处理的甜橙[（L.）Osbeck]‘瓦伦西亚’上感染Las的木虱的口针穿透活动。系统性杀虫剂扰乱了感染Las的木虱的取食行为，从而影响Las的传播效率，特别是对与韧皮部阶段相关的口针活动产生负面影响。所有杀虫剂均降低了（57%-73%）表现出可持续韧皮部取食（波形E2>10分钟）的木虱比例，在噻虫嗪和噻虫嗪+氯虫苯甲酰胺处理的植株上观察到显著差异。高接种压力下（每株植物接种5只感染Las的木虱，接种接入期为7天）Las向未处理对照植株的传播率为93%。相比之下，当试验植株受到系统性杀虫剂保护时，Las的传播率降至38.8%。我们的结果表明，所有测试的杀虫剂都有潜力将Las接种率平均降低59%；因此，这些杀虫剂可用于减少HLB的传播。
