Transmission modes and efficiency of iflavirus and cripavirus in Queensland fruit fly, Bactrocera tryoni

2023

Morrow, Jennifer L.
Sharpe, Stephen R.
Tilden, Geraldine
Wyatt, Pauline
Oczkowicz, Sybilla
Riegler, Markus

Infections of insects with insect-specific RNA viruses are common and can affect host fitness and health. Previously, persistent RNA virus infections were detected in tephritid fruit flies, including the Queensland fruit fly (Bactrocera tryoni), Australia’s most significant horticultural pest. Their transmission modes and efficiency are unclear yet may influence virus epidemiology in field and laboratory populations. Using standard RT-PCR and RT-qPCR we detected iflavirus, cripavirus and sigmavirus in five laboratory populations recently established with field-collected B.tryoni. Virus absence in some individuals suggested that virus transmission is incomplete. Random virus segregation in an isofemale experiment resulted in the establishment of isofemale lines with and without iflavirus and cripavirus. In infected lines, viral loads normalised against host gene transcripts were variable, but did not differ between pupae and adults. Iflavirus and cripavirus were transmitted horizontally, with viruses detected (including at low viral loads) in many previously uninfected individuals after four days, and in most after 12 days cohabitation with infected flies. Iflavirus, but not cripavirus, was transmitted vertically, and surface-sterilised embryos contained high loads. Furthermore, high iflavirus loads in individual females resulted in high loads in their offspring. We demonstrated that viruses are highly prevalent in laboratory populations and that it is possible to establish and maintain uninfected fly lines for the assessment of virus transmission and host effects. This is important for pest management strategies such as the sterile insect technique which requires the mass-rearing of flies, as their fitness and performance may be affected by covert virus infections.

Entomology; Fruit and fruit culture; Plant pests and diseases; Economic entomology; Article; PeerReviewed

BCDLM oai:jdecs1.ecs.soton.ac.uk:9050
Morrow, J. L., Sharpe, S. R., Tilden, G., Wyatt, P., Oczkowicz, S. and Riegler, M. (2023) Transmission modes and efficiency of iflavirus and cripavirus in Queensland fruit fly, Bactrocera tryoni. Journal of Invertebrate Pathology, 197 . p. 107874. ISSN 0022-2011
1370313000

DEPARTMENT OF EMPLOYMENT, ECON DEV & I
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