Hsu Cynthia L, Hoepting Christine A, Fuchs Marc, Shelton Anthony M, Nault Brian A
Department of Entomology, Cornell University, New York State Agricultural Experiment Station, 630 W North Street, Geneva, NY 14456, USA.
Environ Entomol. 2010 Apr;39(2):266-77. doi: 10.1603/EN09165.
Onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), can reduce onion bulb yield and transmit iris yellow spot virus (IYSV) (Bunyaviridae: Tospovirus), which can cause additional yield losses. In New York, onions are planted using seeds and imported transplants. IYSV is not seed transmitted, but infected transplants have been found in other U.S. states. Transplants are also larger than seeded onions early in the season, and thrips, some of which may be viruliferous, may preferentially colonize larger plants. Limited information is available on the temporal dynamics of IYSV and its vector in onion fields. In 2007 and 2008, T. tabaci and IYSV levels were monitored in six seeded and six transplanted fields. We found significantly more thrips in transplanted fields early in the season, but by the end of the season seeded fields had higher levels of IYSV. The percentage of sample sites with IYSV-infected plants remained low (<12%) until August, when infection levels increased dramatically in some fields. The densities of adult and larval thrips in August and September were better predictors of final IYSV levels than early season thrips densities. For 2007 and 2008, the time onions were harvested may have been more important in determining IYSV levels than whether the onions were seeded or transplanted. Viruliferous thrips emigrating from harvested onion fields into nonharvested ones may be increasing the primary spread of IYSV in late-harvested onions. Managing T. tabaci populations before harvest, and manipulating the spatial arrangement of fields based on harvest date could mitigate the spread of IYSV.
葱蓟马，西花蓟马（Lindeman）（缨翅目：蓟马科），会降低洋葱鳞茎产量，并传播鸢尾黄斑病毒（IYSV）（布尼亚病毒科：番茄斑萎病毒属），这会导致额外的产量损失。在纽约，洋葱种植采用种子和进口的移栽苗。IYSV不会通过种子传播，但在美国其他州已发现受感染的移栽苗。移栽苗在季节早期也比播种的洋葱大，而蓟马，其中一些可能携带病毒，可能会优先在较大的植株上定殖。关于IYSV及其传播媒介在洋葱田中的时间动态的信息有限。在2007年和2008年，对六个播种田和六个移栽田中的西花蓟马和IYSV水平进行了监测。我们发现，在季节早期，移栽田中蓟马数量明显更多，但到季节结束时，播种田中的IYSV水平更高。直到8月，IYSV感染植株的采样点百分比一直较低（<12%），此时一些田块的感染水平急剧上升。8月和9月成虫和幼虫蓟马的密度比季节早期蓟马密度更能预测最终的IYSV水平。对于2007年和2008年，洋葱收获时间在决定IYSV水平方面可能比洋葱是播种还是移栽更为重要。从收获的洋葱田迁移到未收获田的带毒蓟马可能正在增加IYSV在晚收洋葱中的主要传播。在收获前管理西花蓟马种群，并根据收获日期调整田块的空间布局，可以减轻IYSV的传播。
