How Does Vector Bemisia Tabaci use Visual and Olfactory Cues in Orientation to A Virus-Infected Host Plant?

Abstract

\n Cucurbit chlorotic yellows virus (CCYV) has caused serious damage to melon crops in many countries in recent years. It is exclusively transmitted by the notorious pest Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in a semi-persistent manner. Previous studies have shown that both persistently and non-persistently transmitted viruses can manipulate orientation and performance of vector insects through changing host phenotype to facilitate virus spread. However, as a semi-persistently transmitted virus, how CCYV affect vector B. tabaci in locating host plants by altering physiological traits of host plants is still unknown. In this study, we investigated B. tabaci visual and olfactory preference between healthy and CCYV-infected host plant Cucumis sativus. Volatile profiles of healthy and CCYV-infected C. sativus plants were analyzed by using gas chromatography-mass spectrometry (GC-MS). Initially, it was found that vector insects preferred to settle down CCYV-infected Cucumis sativus seedlings in free choice. The concentrations of total volatiles and terpenes in cucumber plants were notably decreased after CCYV infection, and especially, the concentrations of α-pinene, β-ocimene, α-farnesene, and nonanal, responsible for olfactory attraction of B. tabaci, dramatically reduced in CCYV-infected plants. Subsequently, we investigated the visual preference of B. tabaci to CCYV-infected and healthy host, and found that B. tabaci adults showed significant preference to CCYV-infected host. CCYV induced yellowing symptoms in host leaves may explain the visual preference of B. tabaci adults to infected hosts. This study indicated that visual cues could play a vital role in vector insects locating virus-infected host plants.