Plant invasion is major global driver to structure and functioning of natural communities. Species diversity is a fundamental determinant of community regeneration and dynamics through flowering phenology and groups. However, the impacts of plant invasion on native plant flowering phenology and how species diversity regulates the process remain unclear. We conducted a field experiment to assess the effects of plant invasion (Solidago canadensis) and community species diversity on flowering phenology of native plants from different flowering functional groups (FFGs) at community and species levels. We found that at community level, plant invasion shortened flowering duration (FD), and reduced flowering synchrony of native communities. Furthermore, high diversity reduced the negative impacts of plant invasion on flowering synchrony. Among FFGs, the late and mid flowering species responded more negatively to plant invasion than the early flowering species. SEM indicated that plant invasion suppressed plant height and FFD or LFD by reducing light availability to native plants, which in turn affected flowering phenology. However, high diversity counteracted the negative effects. Our findings confirm the role of high species diversity in resisting alien plant invasions on flowering phenology and reproduction of native plant communities, and suggest that high diversity with different FFGs should be considered to efficiently restore native communities invaded by alien plants such as S. canadensis.

Huanglongbing (HLB) is the most devastating citrus disease worldwide. The causal organism of the disease is spread by an insect vector, Diaphorina citri, commonly known as Asian citrus psyllid (ACP). Current management of HLB relies either on physical removal of the infected plants or on chemical control of ACP. Both methods are not overly effective and costly. In addition, public concerns regarding insecticide residues in fruit have greatly increased in recent years. It has been hypothesized that plant volatiles could act as repellents to ACP, thus reduce the incidence of HLB. To test this hypothesis, the repellency of fresh tissues of 41 aromatic plant species to ACP was investigated. The repellency of individual species was determined using a Y-tube olfactometer. Our results showed that volatiles of five plant species were highly effective in repelling ACP with repellency as much as 76%. Among these, the tree species, Camptotheca acuminate, and the two shrubs, Lantana camara and Mimosa bimucronata, could potentially be planted as a landscape barrier. The two herbs, Capsicum annuum and Gynura bicolor, could potentially be used as interrow plantings in orchards. This is the first time that the repellency of fresh tissues from a diverse range of plant species to ACP has been determined. Although further field evaluation of various interplanting regimes and landscape barriers are needed to assess their effectiveness, our results showed that these aromatic species, being highly repellent to ACT, offer great potential as more cost-effective and environmentally sustainable alternatives to the current methods of managing HLB.