Taxonomic name: Vespula pensylvanica Rohwer
Synonyms:
Common names: guêpe de l'ouest (French), Pensylvenia-Wespe (German), western yellowjacket (English)
Organism type: insect Western yellowjackets (Vespula pensylvanica) are predators, feeding on a wide range of invertebrate taxa, with great potential for negative impact on the native fauna in insular habitats. Description
Vespula pensylvanica is yellow and black. This is the only wasp species which has a complete yellow eye ring around each compound eye. The queens also have this eye ring (Source: Matthew P. Kweskin). Occurs in:
natural forests, scrub/shrublands, urban areas General impacts
Wasps impact in a range of human activities and values, from conservation, forestry, beekeeping and horticulture sectors to human-health. Wasp stings are painful at best, and life-threatening at worst. A small proportion of the population will have a severe allergic reaction (called anaphylactic shock), which can be fatal unless treated promptly (Landcare Research 2007).
In forests wasps may eat huge numbers of native insects and consume large quantities of sugary honeydew. By eating so much, wasps take potential food sources away from native animals and disrupt the natural food chain and ecosystem cycling of the forest (Landcare Research 2007). Western yellowjackets are predators which prey on a wide range of invertebrate taxa. Their great potential for negative impacts on native invertebrate is evidenced in Hawaii, where they threaten endemic invertebrates (which have evolved in the absence of wasps and without any anti-predator adaptations).
Wasps bring with them a financial burden too. They are economic pests of primary industries such as beekeeping, forestry and horticulture (Beggs 2000). Wasps totally destroy or seriously affect 10% of beehives, which translates to a significant financial loss (Clapperton et al. 1989). Beehives are often placed near honeydew forests or other unique sources of nectar to produce strong-flavoured honey. However, wasps can reduce honey production by reducing nectar and honeydew supplies and cause honeybees to stay home to conserve energy and protect their hive from raiding wasps (Landcare Research 2007). Notes
It looks like New Zealand Vespula vulgaris is not the same as the US species Vespula vulgaris (on the basis of preliminary molecular work), (Beggs, pers.comm., 2003). Geographical range
Native range: The western yellowjacket wasp is native to the western half of temperate North America.
Known introduced range: It has subsequently been introduced to the Hawaiian Islands and other areas. Management information
Chemical: "Almost as soon as the 1977 population was discovered, nest eradication and/or control programmes were initiated on various islands in Hawai‘i to attempt to control the yellowjacket. The toxicant bendiocarb, used for nest eradication, is not registered in the USA for use in agricultural situations, so its implementation had to be outside of agricultural fields. Chang (1988) discusses the use of toxic baiting in the control of yellowjackets. His results showed that the most effective combination of bait and chemical toxicant was 0.5% microencapsulated diazinon mixed with canned Figaro brand tuna cat food. Amidino-hydrazone in a similar bait mix was also effective, but less so than than diazinon mix. Dispenser colour for the bait also proved critical, the preferred colour of bait dispenser being translucent white." Nutrition
Vespula pensylvanica has an affinity to scavenge. In addition, it tends to nest in the open near recreational areas, and is a common visitor to picnic areas and garbage receptacles. Its workers have been known to forage up to 1800 feet from the nest, but the normal foraging range is about 1100 feet. Reproduction
The nests of Vespula pensylvanica are mostly subterranean, often in old rodent burrows. The nests can be large, up to 11,000 cells. This species takes live prey as well as scavenging. V. pensylvanica becomes a pest in the Northwest U.S. where there are outbreaks of high populations every few years (Source: Matthew P. Kweskin).
"Climate is a major constraint on yellowjacket reproductive behaviour; cold weather depletes normal food supplies, resulting in a reduction of colony individuals during cold winter months. However, in Hawai‘i with its warmer year-round climate, colonies appear to enlarge during warm winter months causing population explosions in areas it has invaded."
Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG)
|
|
Last Modified: Tuesday, 25 January 2005
|
