Plant Virus Transmission by Insects

Abstract

Most plant viruses depend on insect vectors for their survival, transmission and spread. They transmit plant viruses by two principal modes, circulative (circulating through the insect's haemocoel, CV) and non‐circulative (carried on the cuticle lining of mouthparts or foregut, NC). Transmissibility and specificity between NC viruses and their vectors depends on the coat protein (CP) of the virus in addition to virus‐encoded helper proteins. Circulative viruses cross the gut, circulate in the haemocoel and cross the salivary glands to render the insect infective. Circulative luteoviruses depend on small CP and the read‐through protein (RTD) for transmission. Electrical penetration graphs have provided evidence on insect feeding behaviour and virus transmission. Recently, studies have shown that viruses can modify vector behaviour in a way that transmission is enhanced. Cultural, physical and novel biotechnological tools can provide virus control by interfering with vector landing and the retention of viruses in their vectors. Key Concepts Most plant viruses rely on insect vectors for survival, transmission and spread. Aphids and whiteflies are by far the most important insects transmitting plant viruses. Some plant viruses are associated to the cuticle of the insect mouthparts (non‐circulative), whereas others are retained in the salivary glands after they circulate through the insect's body (circulative). Some non‐circulative viruses are retained in the common duct of the aphid's maxillary stylets and are inoculated by salivation during brief superficial intracellular probes. Circulative viruses are inoculated during salivation stylet activities in phloem sieve elements. Recent findings in the nature of insect proteins involved in the retention of virus or virus‐encoded helper proteins will help to develop new molecules to interfere with the transmission process.

Incidence of viruses and virus-like diseases of watermelons and pumpkins in Uganda, a hitherto none-investigated pathosystem

“…However, the impact of plant virus diseases is exacerbated in the tropics because tropical conditions favour continuous presence of both primary and secondary hosts and super-abundance of vectors that efficiently transmit the viruses (Fargette et al, 2006;Morales, 2007;Barult et al, 2010;NavasCastillo et al, 2011;Geering and Randles, 2012;Fereres and Raccah, 2015). Moreover, virus diseases in nonpriority crops at local or regional scale when ignored or left to 'fallow' may constitute none investigated pathosystems as sources of harmful viruses in surrounding cropping systems (Jones et al, 2010;Lebeda and Burdon, 2013).…”

Plant Virus Ecology: A Glimpse of Recent Accomplishments

“…Further studies describes that plant infected by persistent viruses are more attractive than infected by non persistent ones (Mauck et al, 2012). The transmission of plant viruses can be carried out by insects in two principal methods; one is circulative pathway which includes circulation of viruses through the haemocoel of the insect and the other is non circulative which only involves the foregut or mouth parts of the insect (Fereres and Raccah, 2015).…”

RNA Interference in Insect Vectors for Plant Viruses

“…Insect vector for plant pathogens can be found in seven of the 32 orders in the Insecta [52]. However, among these, sap-sucking insects that include aphids, whiteflies, hoppers, thrips and beetles are the major vectors that transmit the highest diversity and most important plant pathogens.…”

“…Aphids are the largest group of insects that transmit plant viruses and it is estimated that 28% of all plant viruses that belong to eight families, 18 genera, and some taxonomically unassigned viruses are transmitted by aphids [1,52]. RNAi has been successfully applied in aphids and silencing of aphid genes has shown significant effects on the insects such as mortality and reduction in fecundity.…”