Overwintering ofFrankliniella fusca(Thysanoptera: Thripidae) on Winter Annual Weeds Infected withTomato spotted wilt virusand Patterns of Virus Movement Between Susceptible Weed Hosts

Abstract

Overwintering of tobacco thrips, Frankliniella fusca, was investigated on common winter annual host plants infected with Tomato spotted wilt virus (TSWV). Populations of tobacco thrips produced on TSWV-infected plants did not differ from those produced on healthy plants, whereas populations varied greatly among host plant species. The mean per plant populations of F. fusca averaged 401, 162, and 10 thrips per plant on Stellaria media, Scleranthus annuus, and Sonchus asper, respectively, during peak abundance in May. Adult F. fusca collected from plant hosts were predominately brachypterous throughout the winter and early spring, but macropterous forms predominated in late spring. Weed hosts varied in their ability to serve as overwintering sources of TSWV inoculum. Following the initial infection by TSWV in October 1997, 75% of Scleranthus annuus and Stellaria media retained infection over the winter and spring season, whereas only 17% of Sonchus asper plants remained infected throughout the same interval. Mortality of TSWV-infected Sonchus asper plants exceeded 25%, but mortality of infected Stellaria media and Scleranthus annuus did not exceed 8%. TSWV transmission by thrips produced on infected plants was greatest on Stellaria media (18%), intermediate on Scleranthus annuus (6%), and lowest on Sonchus asper (2%). Very few viruliferous F. fusca were recovered from soil samples collected below infected wild host plants. Vegetative growth stages of Stellaria media, Sonchus asper, and Ranunculus sardous were more susceptible to F. fusca transmission of TSWV than flowering growth stages, whereas both growth stages of Scleranthus annuus were equally susceptible. In a field study to monitor the spatial and temporal patterns of virus movement from a central source of TSWV-infected Stellaria media to adjacent plots of R. sardous, the incidence of infection in R. sardous plots increased from <1% in March to >42% in June 1999. Infection levels in the Stellaria media inoculum source remained high throughout the experiment, averaging nearly 80% until June 1999 when all Stellaria media plants had senesced. Dispersal of TSWV from the inoculum source extended to the limits of the experimental plot (>37 m). Significant directional patterns of TSWV spread to the R. sardous plots were detected in April and May but not in June. R. sardous infections were detected as early as March and April, suggesting that overwintering inoculum levels in an area can increase rapidly during the spring in susceptible weed hosts prior to planting of susceptible crops. This increase in the abundance of TSWV inoculum sources occurs at a time when vector populations are increasing rapidly. The spread of TSWV among weeds in the spring serves to bridge the period when overwintered inoculum sources decline and susceptible crops are planted.

Viral genetic determinants for thrips transmission of Tomato spotted wilt virus

“…Among those, Frankliniella occidentalis (western flower thrips) and Frankliniella fusca (tobacco thrips) are the most efficient vectors in the southeastern United States (26). Unlike the other arthropod-borne members of the Bunyaviridae, old second instar larvae and adults can become transmitters of TSWV only if the virus is acquired by the thrips in the first instar larval stage (27,28).…”

Temporal and spatial dispersal of Melon yellow spot virus in cucumber greenhouses and evaluation of weeds as infection sources

“…However, further work is needed to clarify the extent to which weeds are involved in the infection cycle of MYSV, since only a few species of weeds were used in these experiments. In addition, titres and the localities of MYSV in weeds, food consumption and survival rates of T. palmi from MYSV-infected weeds, and growth stage of the host plants are presumed to affect the acquisition and transmission of tospovirus (Groves et al 2001;Okazaki et al 2009). In our study, RT-PCR was used for the detection of MYSV.…”

“…Tomato spotted wilt virus (TSWV) of the genus Tospovirus has a broad host range consisting of more than 1,000 species (Parrella et al 2003), including many weed species (Chatzivassiliou et al 2007;Groves et al 2001;McPherson et al 2003;Mertelik et al 1996;Okazaki et al 2007). Weeds not only carry viruses, but also provide habitats for vectors such as thrips during non-cropping periods.…”

Winter Occurance and Spring Migration of Frankliniella fusca (Hinds) (Thysanoptera: Tripidae) in North Carolina Peanut (Arachis hypogaea L.) Fields

“…However, it seems more likely they transmit TSWV to alternate host plants where it can be acquired by subsequent generations of tobacco thrips in the spring, which then transmit the virus to other plants including peanuts. Groves et al (2001) demonstrated that both tobacco thrips and western flower thrips (F. occidentalis) overwintering on infected winter annual weeds spread TSWV to other weeds in late winter and early spring.…”