Odor, Not Performance, Dictates 's Selection between Healthy and Virus Infected Plants.

Although, insect herbivores are generally thought to select hosts that favor the fitness of their progeny, this "mother-knows-best" hypothesis may be challenged by the presence of a plant virus. Our previous study showed that the whitefly, , the obligate vector for transmitting (TYLCV), preferred to settle and oviposit on TYLCV-infected rather than healthy host plant, . The performances of larvae and adults were indeed improved on virus-infected , which is consistent with "mother-knows-best" hypothesis. In this study, Q displayed the same preference to settle and oviposit on (TSWV)-infected host plants, and , respectively. As a non-vector of TSWV, however, insect performance was impaired since adult body size, longevity, survival, and fecundity were reduced in TSWV infected . This appears to be an odor-mediated behavior, as plant volatile profiles are modified by viral infection. Infected plants have reduced quantities of o-xylene and α-pinene, and increased levels of phenol and 2-ethyl-1-hexanol in their headspace. Subsequent behavior experiments showed that o-xylene and α-pinene are repellant, while phenol and 2-ethyl-1-hexanol are attractive. This indicates that the preference of for virus-infected plants is modulated by the dynamic changes in the volatile profiles rather than the subsequent performances on virus-infected plants.