Multispecies interactions among a plant parasite, a pollinator and a seed predator affect the reproductive output of an invasive plant, Cytisus scoparius

Abstract

Interactions between species pairs are almost always mediated by interactions with other species. The outcomes of these multispecies interactions are often difficult to predict and are rarely studied. In addition to their theoretical importance, multispecies interactions are also important for management situations. Where multiple agents are used to control invasive species, interactions between agents may either enhance or reduce the impacts on the target species, or may simply have additive effects. In this study, conducted in a Mediterranean-type woodland in Australia, we examined how the interaction between an invasive legume, Cytisus scoparius (Leguminosae), its pollinator, Apis mellifera and a seed predator, Bruchidius villosus (Bruchidae), are modified by a native hemiparasitic vine, Cassytha pubescens (Loranthaceae). The parasite had a direct negative effect on C. scoparius, reducing flowering by 50% and consequently fruit and seed production. Despite having fewer flowers, infected plants had the same proportion of 'tripped' flowers, an indirect measure of pollinator visitation, as uninfected plants; although fruit formed on infected plants it was more likely to abort prematurely. Seed predation by B. villosus was lower on parasite-infected C. scoparius plants than in uninfected plants. Although Ca. pubescens had an antagonistic effect on B. villosus, in consort, the two agents reduced overall seed production by an average of 62%. The acquired parasite Ca. pubescens was more effective in reducing reproductive output than the introduced seed predator, B. villosus, and shows potential as a biocontrol agent for C. scoparius. We documented a subadditive effect of two biological enemies on the invasive species, where the acquired parasite had a stronger effect than the introduced seed predator.

Native parasitic plants: Biological control for plant invasions?

“…Similar evidence of chronic photoinhibition has been reported for another invader, Cytisus scoparius, when infected with C. pubescens (Shen et al, 2010). Control of U. europaeus and C. scoparius by C. pubescens could complement biological control using phytophagous insects (Prider et al, 2011).…”

Parasite Removal, but Not Herbivory, Deters Future Parasite Attachment on Tomato

“…The differences between these treatments suggest that the effects of prior interactions depend not just on the identity of the antagonist (i.e., herbivore vs. parasite), but also on the outcome of the interaction. Given that prior parasite attachment can reduce subsequent herbivory and deter pollinators [ 46 ], we suggest experiments testing whether these two dodder induction treatments vary in their effects on subsequent herbivore attraction, pollinator attraction, and fruit yield. Although tomato plants are largely self-fertile, pollinators are required to yield fruit [ 47 ], so the effects of parasites on pollinators are particularly relevant in agriculture.…”

Comparison of Allergenicity of Mature Pollen Grains and Petals in Two Ontogenic Stages in Cytisus scoparius L.

“…Since seasonal sensitivities increase in the spring and allergic reactions occur in sensitive people, especially children and the elderly, investigating allergenicity of the pollen grains and aromatic petalsin plants that pollinatein the spring is necessary. Because the pollen grains of this plant are carried by bumblebees and wasps (21,24), it is possible that pollen grains containing allergen compounds used in honey production can enter the human body (8,25). Our research in 2014, showed allergenicity petals of old ontogenical (26).…”

“…This beautiful and extremely fragrant flower is native to Europe and North Africa and has subsequently spread to Asia (18)(19)(20). The flowering period is between the months of May and June (19)(20)(21)(22)(23)(24). Since seasonal sensitivities increase in the spring and allergic reactions occur in sensitive people, especially children and the elderly, investigating allergenicity of the pollen grains and aromatic petalsin plants that pollinatein the spring is necessary.…”