Carbonell, D. | Search bioRxiv

bioRxiv2025

Interactions between a spider mite and a virus revealed via effects on their host plant.

Coinfection, when hosts are infected with more than one parasite, can modify life-history traits of both parasites and their host. We investigated reciprocal interactions between tomato spotted wilt virus (TSWV) and a non-vector spider mite, Tetranychus urticae, in coinfections on tomato plants. We compared the number of T. urticae daughters and adults and the viral load for two TSWV isolates (France81, which is more virulent, and LYE1137vir) in single and coinfections, and measured host traits (height, fresh weight, chlorophyll content, and number of flowers). TSWV infection reduced plant height, weight, flowers and chlorophyll content, especially when infected with isolate France81. T. urticae only reduced plant height. The more virulent TSWV isolate facilitated spider mites by increasing the number of daughters per unit of plant height, thus potentially enabling equivalent levels of mite transmission as from virus-free plants. In contrast, there was no effect of T. urticae on the load of either TSWV isolate. Nevertheless, the additive reduction in plant height in coinfection may increase host mortality and reduce the time available for transmission of both parasites. This work highlights that it can be important to incorporate measures of host and parasite life-history traits across an entire infection when investigating the consequences of coinfection for parasite fitness.

evolutionary biology↗

bioRxiv2024

Tomato spotted wilt virus facilitates non-vector spider mite species (Tetranychus urticae and Tetranychus evansi) on whole tomato plants

Coinfections where hosts harbour more than one parasite species are common in nature. Facilitation among parasites enabling them to better exploit host resources is widespread with direct consequences on their life-history. Plant viruses can facilitate their vectors to increase their transmission, but equivalent studies in virus-non vectors are lacking. Here we study facilitation of two (non-vector) species of Tetranychus spider mites, Tetranychus urticae and T. evansi, by a plant virus, tomato spotted wilt virus (TSWV), in coinfections on a host tomato plant, Solanum lycopersicum. We compared the effect of different strains of TSWV on life-history traits of Tetranychus mites on cut leaves and whole plants of different tomato varieties. TSWV facilitated both species of spider mite on two different tomato varieties on whole plants, with more offspring of both species becoming adults. In contrast, on cut leaves, facilitation of T. urticae was much more variable depending on the experiment, viral strain and tomato variety. We attribute this to the non-homogeneous spread of virus throughout the host plant. Virus is first transported to the top leaves, and not middle leaves which we had used for the experiment. Indeed, if facilitation is indirect via the host immune system or resource based via the release of free-amino acids then this may be less efficient on cut plant parts. These results highlight that facilitation among parasites may increase parasite fitness and at the same time levels of virulence experienced by the host.

ecology↗