Analysis of Iris yellow spot virus replication in vector and non‐vector thrips species

Abstract

Iris yellow spot virus (IYSV, genus Tospovirus) is a viral disease of bulb and seed onion crops and is transmitted by Thrips tabaci. Foliage damage of up to 75% has been reported in Kenya and Uganda. In this study, the rate of IYSV replication in the larva, pupa and adult stages of T. tabaci and other non-vector thrips species and colour forms such as Frankliniella occidentalis, F. schultzei (dark) and F. schultzei (pale) was evaluated by monitoring relative levels of nucleocapsid (N) and non-structural (NSs) proteins using N-and NSs-specific antibodies. The effect of IYSV replication on mortality of thrips was also determined. N protein levels increased in all three stages of IYSV-fed T. tabaci, indicating replication of IYSV. In IYSV-fed non-vector thrips, the increase of N protein levels in the larval stage was lower than IYSV-fed T. tabaci but higher than their healthy counterparts. The N protein levels did not increase at pupal and adult stages. NSs protein was not detected in first instar of either vector or non-vector thrips species. After a 4 h postacquisition period, a significant increase in NSs proteins was only observed in IYSV-fed T. tabaci, clearly differentiating vectors and non-vectors of IYSV. IYSV replication did not influence the survival of the vector thrips species, T. tabaci populations or the non-vector thrips species. This study indicates the effectiveness of monitoring non-structural proteins such as NSs, compared to nucleocapsid proteins, for differentiating vectors and non-vectors of IYSV.

Tomato yellow leaf curl virus: No evidence for replication in the insect vector Bemisia tabaci

“…Similar results were obtained for TYLCV-Mld or TYLCV-IL with either the MEAM1 or the MED species of B. tabaci . In contrast, increased virus accumulation in the insect vector in time-frames similar to those used here was shown for propagative plant RNA viruses of the genus Tospovirus (family Bunyaviridae ) in thrips 24 25 26 or Tenuivirus in planthoppers 27 . More than a ten-fold titer increase was observed for the plant RNA and aphid-borne virus raspberry latent virus (family Reoviridae ) in its insect vector at five days post-AAP 28 .…”

Endophytic Colonization of Onions Induces Resistance Against Viruliferous Thrips and Virus Replication

“…A cohort of 500 first instar (≤ 8 h-old) T. tabaci obtained from icipe ’s insectary were allowed to acquire virus by feeding on IYSV-infected Allium cepa var. Red creole (plants maintained at icipe as virus inoculum source) for an acquisition access period (AAP) of 16 h. The virus infection in the plants leaves (1 g) used for virus acquisition was confirmed using IYSV-specific ELISA Flashkit (Agdia Biofords, Netherlands) (Birithia et al, 2013). Thrips were then transferred and reared on snow pea pods until adults emerged.…”

“…Iris yellow spot virus is transmitted by T. tabaci in a circulative and propagative manner (Whitfield et al, 2005). The virus is acquired by the first or second larval stages and it then multiplies and survives through the later developmental stages (Whitfield et al, 2005; Birithia et al, 2013). Adult thrips emerging from thrips larvae that had acquired IYSV are viruliferous and can transmit the virus.…”

Occurrence of iris yellow spot virus from onion crops in Egypt

“…Newly hatched larvae were collected and reared on bean pods [11]. Groups of virus-free thrips, newly hatched larvae were placed on IYSV-Egypt-infected D. stramonium L. plants with symptoms for 2 h and then transferred to healthy onion seedlings in another cage for 24 h. Subsequently, thrips were killed by spraying with 0.01 % Malathion and plants were observed for developing virus symptoms for 4 weeks.…”