Vespula wasp distribution
The first non-native wasps collected on Navarino Island in 2015 were identified as V. vulgaris, with all records being in the urban environment of Puerto Williams. During 2016, the presence of V. vulgaris was documented far from the main town (~30 km to the east and 10 km to the west), although nests were found predominantly in peri-urban settings with evident anthropogenic activity impact (non-authorized waste collection sites and forestry management depots) and inhabited rural settings (farms, greenhouses). Much wider distribution expansion in the natural environment remote from human settlements became apparent in 2017, during which V. vulgaris was recorded along virtually the entire north coast of Navarino Island, approximately 90 km in length (Fig. 2). In the same year, the species was recorded in the isolated Puerto Toro (a village on the east coast of Navarino Island), and in Yendegaia National Park (Fig. 2). In the summers of 2018 and 2019, V. vulgaris was present throughout the north coast of the island, in Puerto Toro and had reached the southwest of the island (Wulaia), as well as being documented for the first time in Hoste Island. In addition to being present in almost all terrestrial ecosystems, a V. vulgaris nest was recorded at 450 m a.s.l., close to the tree line on Navarino Island. During the summers of 2020 and 2021, V. vulgaris was found off the forest margin of Windhond lake in the southern part of the island, south of the Dientes de Navarino mountain range, and towards the southeast. In addition, V. vulgaris workers were found foraging in different habitats through valleys (forests, shrublands and peatlands), from low elevations up to the tree line (500-600 m a.s.l.). Nests were recorded along hiking trails, in dead and living trees, old growth and secondary forests, peat bog margins and in riparian habitats close to streams and lagoons.
The first specimens of V. germanica were recorded and collected in 2016 at four different locations within Navarino Island (queens n = 2, workers n = 10, Fig. 3). During 2017, workers (n = 15) and a single drone were collected at the same locations. During 2018 and 2019, V. germanica workers were recorded at 12 locations, the majority of these being new (Fig. 3). During 2020 and 2021, no records of V. germanica were noted. All records to date have been along the north coast of Navarino Island, and no nests have yet been located.
Foraging associations
Vespula wasps have a broad association with the biotic components of the habitats they nest in, and workers are commonly seen exploiting resources for food and nest maintenance (Table 1). Significant differences in foraged item composition were found between all habitats (PERMANOVA, F = 10.188 p = 0.001, Table 2, Fig. 5). The most frequent prey items were dipterans (mainly Tipulidae and Syrphidae), particularly in deciduous, evergreen, and mixed forests (Fig. 6). Occasional prey such as beetles, moths, spiders and dragonflies were less frequently observed in the surveyed nests and related to their presence in a particular habitat (Table 1, Fig. 6). The main non-insect source foraged by workers were berries, mainly Berberis microphylla, which are common through the island. Other berries (Rubus geoides and Ribes magellanicum) were foraged in the specific habitats in which they grow (Fig. 6). Items that are related to nest maintenance (liquids and pulp) were common and regularly foraged in all habitats (Fig. 6). Regarding the associations of V. vulgaris with native and non-native biota of the CHBR, 16 plant associations were found, of which only three species were non-native (Table 2). The type of interaction was mainly foraging berries in shrubs of the genera Berberis, Empetrum, Ribes and Rubus. Wasps have also been found robbing nectar, eating petals from flowers, preying on arthropods associated with trees and shrubs and chewing branches for wood pulp. Regarding the interactions with fauna, we found an association with nine different native invertebrate species, mostly involving predation.
Nest activity
Activity was broadly comparable across all four habitat types, although significant differences were detected (Kruskal-Wallis H = 22.9924; p < 0.001, Table 3). The mean nest activity measured in evergreen forests was significantly lower compared to shrublands and mixed forests (Fig. 4). Recorded nest activity in deciduous forests was highly variable (see Table 3, Fig. 4) and significantly different from the activity in shrublands and mixed forests but not that in evergreen forests.
Table 1. Vespula wasp associations with native and non-native biota in the Cape Horn Biosphere Reserve, southern Chile.
Species/ organisms
|
Flora/ fauna
|
Origin
|
Nature of interaction
|
Baccharis patagonica
|
Shrub
|
Native
|
Hunting for arthropods
|
Berberis microphylla
|
Shrub
|
Native
|
Foraging berries
|
Berberis ilicifolia
|
Shrub
|
Native
|
Foraging berries
|
Chiliotrichum diffusum
|
Shrub
|
Native
|
Hunting for arthropods
|
Drimys winteri
|
Tree
|
Native
|
Eating petals from flowers
|
Embothrium coccineum
|
Tree
|
Native
|
Nectar robbing
|
Empetrum rubrum
|
Shrub
|
Native
|
Foraging berries
|
Gaultheria mucronata
|
Shrub
|
Native
|
Foraging berries
|
Nothofagus antarctica
|
Tree
|
Native
|
Hunting for arthropods and chewing branches for wood pulp
|
Nothofagus betuloides
|
Tree
|
Native
|
Hunting for arthropods and chewing branches for wood pulp
|
Nothofagus pumilio
|
Tree
|
Native
|
Hunting for arthropods and chewing branches for wood pulp
|
Ribes magellanicum
|
Shrub
|
Native
|
Foraging berries
|
Ribes uva-crispa
|
Shrub
|
Non-native
|
Foraging berries
|
Rubus geoides
|
Herb
|
Native
|
Foraging berries
|
Rubus idaeus
|
Herb
|
Non-native
|
Foraging berries
|
Taraxacum officinale
|
Dandelion
|
Non-native
|
Eating petals from flowers
|
Aegorhinus vitulus
|
Weevil
|
Native
|
Predation
|
Ericchius femoralis
|
Stag beetle
|
Native
|
Opportunistic robbery of tree sap while beetles feed
|
Rhionaeschna variegata
|
Dragonfly
|
Native
|
Defence when approaches nests
|
Anyphaenidae
|
Spiders
|
Native
|
Predation
|
Araneidae
|
Spiders
|
Native
|
Predation
|
Geometridae
|
Geometer moths
|
Native
|
Predation on larvae
|
Lycosidae
|
Spiders
|
Native
|
Predation
|
Syrphidae
|
Hover flies
|
Native
|
Predation
|
Tipulidae
|
Crane flies
|
Native
|
Predation
|
Table 2. PERMANOVA analysis and post hoc pairwise comparisons of Vespula vulgaris foraged item composition in different habitats on Navarino Island, Cape Horn Biosphere Reserve, southern Chile.
Source
|
df
|
SS
|
MS
|
F
|
p
|
Habitat
|
3
|
5599.7
|
1866.6
|
10.188
|
0.001
|
Res
|
28
|
5130.1
|
183.22
|
|
|
Habitat
|
t
|
p
|
|
Deciduous forest - Evergreen forest
|
3.4228
|
0.001
|
|
Deciduous forest - Mixed forest
|
2.7385
|
0.002
|
|
Deciduous forest - Shrubland
|
3.1166
|
0.001
|
|
Evergreen forest - Mixed forest
|
3.148
|
0.001
|
|
Evergreen forest - Shrubland
|
4.5562
|
0.001
|
|
Mixed forest - Shrubland
|
2.4664
|
0.001
|
|
Table 3. Mean (±SE), maximum and minimum, Kruskal-Wallis non-parametric analyses and Wilcoxon post hoc comparisons of wasp nest activity (numbers entering and leaving the nest) measured in February 2018 at the entrances of Vespula vulgaris nests in different habitat types on Navarino Island, Cape Horn Biosphere Reserve, southern Chile.
Habitat type
|
Deciduous forest
|
Evergreen forest
|
Mixed forest
|
Shrubland
|
Mean ±SE
|
46.28 (±6.77)
|
36.45 (±2.60)
|
51.95 (±2.85)
|
50.5 (±1.78)
|
Max
|
155
|
69
|
76
|
69
|
Min
|
7
|
14
|
21
|
32
|
Kruskal-Wallis
|
H
|
p
|
|
|
|
22.9924
|
<0.001
|
|
|
Wilcoxon comparisons
|
|
|
|
|
Deciduous forest
|
|
|
|
|
Evergreen forest
|
1
|
|
|
|
Mixed forest
|
0.004
|
0.004
|
|
|
Shrubland
|
0.005
|
0.005
|
1
|
|