Damage levels from arthropod herbivores on Lonicera maackii suggest enemy release in its introduced range

Abstract

The 'enemy release hypothesis' argues when a species is introduced to a novel habitat, release from regulation by herbivores results in increased vigor, abundance, and distribution. The invasive Asian shrub Lonicera maackii appears to benefit from an absence of arthropod herbivores in North America. We assessed the incidence, amount, and type of herbivory occurring on L. maackii in forest edge and interior habitats and investigated differences in timing of damage. In October 2008, leaves were sampled from shrubs in forest interior and edge habitat from 8 sites in Ohio. In 2009, sampling was repeated at 3 sites in spring, summer, and fall with a distinction made between long and short branches. Leaf area removed averaged 1.83% across the 8 populations in 2008 and 3.09% across the 3 populations in 2009, with forest edge plants receiving slightly more damage than forest interior plants in 2008. Additionally, long shoots received more damage than short shoots in 2009. Damage incidence was also higher in the edge habitat and on long shoots compared to short shoots. As measured in 2009, damage accumulated steadily throughout the season. Chewing was the most prevalent type of damage (76. 8%) and low level of pathogen infection was observed (4.81%). Results indicate that levels of herbivory experienced by L. maackii are relatively consistent across sites, vary slightly with habitat and branch identity, but are likely too low to impact fitness of shrubs. These findings indicate that low amounts of arthropod herbivory occur for L. maackii across its introduced range, which may contribute to its invasive success.

White-tailed deer browse on an invasive shrub with extended leaf phenology meets assumptions of an apparent competition hypothesis

“…Herbivory by invertebrates on L. maackii is very low ( Lieurance and Cipollini 2011 ). However, Guiden et al (2015) reported that deer browse occurred on 62 % of L. maackii branches during late fall/early winter.…”

Response of Five Miscanthus sinensis Cultivars to Grasshopper Herbivory: Implications for Monitoring of Invasive Grasses in Protected Areas

“…Only grazed portions left by grasshoppers (i.e., noticeable consumed portions along the midrib) were used to assess the leaf damage. Visual assessment of leaf damage was conducted in both, the field and cage experiments, and the percentage of apparent leaf damage was measured following previous studies [ 39 , 40 , 41 ]. Multiple categories of leaf damage were established based on leaf damage score following Lieurance and Cipollini [ 40 ] but with increments of 10% for damage more than 10%: <1%, 1–2%, 2–5%, 6–10%, 11–20%, 21–30%, 31–40%, 41–50%, etc.…”

Long-term interactive impacts of the invasive shrubLonicera maackiiand white-tailed deer (Odocoileus virginianus) on a deciduous forest understory

“…Although L. maackii in its invasive range in North America has been described as benefiting from escape from herbivory (Lieurance and Cipollini 2012), that study assessed only insect herbivores. Lonicera maackii does suffer substantial herbivory by deer, particularly in the early spring and late summer (Martinod and Gorchov 2017) and where it is sparse (Wright et al 2019).…”