|Novelli, V. M. - CACSM/IAC, BRAZIL|
|Freitas-Astua, J. - EMBRAPA, BRAZIL|
|Kitajima, E. W. - NAP/MEPA, BRAZIL|
|Machado, M. A. - CACSM/IAC, BRAZIL|
Submitted to: Conference of International Organization of Citrus Virologists
Publication Type: Abstract Only
Publication Acceptance Date: August 10, 2007
Publication Date: N/A
Interpretive Summary: Citrus leprosis virus (CiLV) causes substantial financial loss due to tree and crop damage in citrus orchards in many areas of Brazil. The virus is transmitted by a small animal called a mite, which has the scientific name Brevipalpis phoenicis. Many mites have bacteria living in them which control basic biological characters of the mite, such as whether the mite will be male or female. Research was conducted to see if the bacterium in this mite, called a Cardinum endoysmbiont affected the ability of the mite to transmit CiLV. When the bacterium was removed from some mites by antibiotic treatments, the mites were still able to transmit the virus, indicating that the ability to transmit the virus is controlled by the mite and not by the bacterium.
Technical Abstract: Citrus leprosis is a viral disease of significant economic and environmental impact in Brazil and some other countries in the Americas. Citrus leprosis virus (CiLV), its causal agent, is transmitted by Brevipalpus phoenicis (Acari: Tenuipalpidae), a polyphagous mite that reproduces through thelytokous parthenogenesis. The presence of the Cardinium endosymbiont is associated with feminization in these mites and alterations in reproduction in several other arthropod hosts. In some plant virus-vector relationships, endosymbiont bacteria play important roles in the arthropod’s capacity to transmit plant viruses. However, it was not known whether or not the Cardinium had any influence on CiLV transmission by the mite vector. Our research program, which also addresses the prevalence and variability of the Brevipalpus endosymbiont, investigated this vector-symbiont-virus interaction. Three populations of B. phoenicis were used; (1) male mites free of Cardinium (derived from tetracycline treatment of the female parentals), (2) females treated with antibiotic, and (3) a control group of females with no antibiotic treatment. These populations were maintained on sources of CiLV inoculum for 72 hours, and were then used to infest sweet orange var. Pera plants. Leprosis symptoms started to appear 25 days after infestation, and all plants from all treatments presented typical leprosis lesions. These preliminary results suggest that both acquisition and inoculation of CiLV by B. phoenicis are not Cardinium-dependent and, hence, the endosymbiont does not seem to play a role in the citrus leprosis pathosystem.