Tospovirus transmission depends on thrips ontogeny

The acquisition of tospoviruses by thrips vectors is restricted to a well defined time period during the first and early second larval stages, when there is a temporary association between mid-gut, visceral muscles and salivary glands. This association is the result of a displacement of the brain into the prothoracic region by enlarged cibarial muscles. The subsequent loss of this association leads to a strong input of virus particles into the malpighian tubules via the haemocoel. Mechanical transmission through excrement and oviposition by adults is a possible alternative mode of virus transmission that requires investigation.