Cassava whitefly are a group of cryptic species within the Bemisia tabaci sensu lato complex that causes significant damage to cassava in Africa. B. tabaci Sub-Saharan Africa 1 (SSA1) is the major species in the study region which transmits plant-virus diseases to cassava and causes direct feeding damage. Benefits from management of cassava viral diseases through deployment of resistant varieties are being undermined by their susceptibility to B. tabaci SSA1 and the problem is exacerbated by high populations of B. tabaci in cassava fields. To develop a clean seed system that is disease-free, the judicious use of insecticides is required to manage this pest and vector. This study evaluated the effect of timing of insecticide application on controlling B. tabaci SSA1 population abundance and damage to cassava. Field trials were carried out between 2017 and 2018 in Kamuli and Wakiso districts of Uganda using the widely available insecticide Imidacloprid. Three cassava cultivars (NAROCASS1, SAUTI, KBH/2002/026) were planted in a randomized complete block trial design replicated three times. The insecticide was applied in split-plots designated as: (i) no protection (NP), no insecticide applied (control), (ii) early protection (EP), insecticide applied 2 times between 0 and 4 months after planting, (iii) long protection (LP), insecticide applied 3 times between 0 and 8 months after planting, and (iv) total protection (TP), insecticide applied 4 times between 0 and 12 months after planting. Except for control plots, stem cuttings were first dipped into a diluted solution of Imidacloprid prior to planting. Bi-monthly data were collected on the B. tabaci population, feeding damage, cassava mosaic disease and cassava brown streak disease. Stem cuttings and root yields were determined at harvest. The marginal rate of return for each treatment was calculated to determine cost effectiveness. Insecticide application effectively reduced B. tabaci populations, feeding damage and disease spread. Cassava yield differed significantly with insecticide treatment and amongst cultivars. Root and stem yield losses of >60% was recorded in unprotected control plots. The marginal rate of return of the early protection (0–4 MAP) program was 163%. We discuss these findings and the implication for judicious use of insecticides as part of a cassava clean seed system.

木薯粉虱是烟粉虱复合体中的一组神秘物种，对非洲的木薯造成重大损害。烟粉虱撒哈拉以南非洲 1 (SSA1) 是研究区域内将植物病毒病传播给木薯并造成直接采食损害的主要物种。通过部署抗性品种来管理木薯病毒病的好处正在被它们对B的易感性所破坏。烟粉虱SSA1 和B的高种群加剧了该问题。烟粉在木薯田里。为了开发无病的清洁种子系统，需要明智地使用杀虫剂来管理这种害虫和媒介。本研究评估了杀虫剂施用时间对控制B的影响。烟粉SSA1 种群丰度和对木薯的损害。2017 年至 2018 年期间，在乌干达的 Kamuli 和 Wakiso 地区使用广泛可用的杀虫剂吡虫啉进行了田间试验。三种木薯品种（NAROCASS1、SAUTI、KBH/2002/026）以随机完整区组试验设计种植，重复 3 次。杀虫剂在指定为的裂区施用：（i）无保护（NP），不施用杀虫剂（对照），（ii）早期保护（EP），在种植后0到4个月之间施用2次杀虫剂，（iii ) 长效保护 (LP)，在种植后 0 到 8 个月之间施用 3 次杀虫剂，以及 (iv) 全面保护 (TP)，在种植后 0 到 12 个月之间施用 4 次杀虫剂。除对照地块外，在种植前首先将茎插条浸入吡虫啉的稀释溶液中。B. 烟粉虱种群、摄食损害、木薯花叶病和木薯褐条病。在收获时测定茎插条和根产量。计算每种治疗的边际回报率以确定成本效益。杀虫剂的应用有效地减少了烟粉虱的数量、摄食损害和疾病传播。木薯产量在杀虫剂处理和品种之间显着不同。在未受保护的对照地块中记录到 > 60% 的根和茎产量损失。早期保护（0-4 MAP）计划的边际回报率为 163%。我们讨论了这些发现以及明智地使用杀虫剂作为木薯清洁种子系统一部分的意义。