Management Information for germanica

Preventative measures: The early detection of establishing populations is important as the next line of defence after initial quarantine procedures. Landcare Research has conducted research into generalised invertebrate surveillance techniques in recognition of the gap in biosecurity surveillance. These include malaise traps, mini-malaise traps, window traps, sticky traps, pitfall traps, UV light traps, flat ant traps, baited ant pottles, spurr traps, ground bottle traps, yellow pan traps and beating. Of these, malaise traps, mini-malaise traps, window traps, sticky traps (for small ), UV traps, spurr wasp traps and ground bottle traps were found to be effective at catching wasps. Please follow this link for descriptions of trapping methods

As there is very little generalised surveying of invertebrates in high risk environments, the primary source of information on the establishment of new invertebrate species is often public observation (Landcare Research, 2007).

Physical Control: There are two ways of reducing a local wasp problem; either find and destroy all in the area, or use poison bait (Landcare Research, 2007). Manual destruction of nests over large areas of shrub land is likely to be difficult and labour intensive (Toft & Harris, 2004).

Chemical Control: Poison baiting is widely used to control wasp populations as it has the advantage that foraging wasps carry the poison back to the , meaning it is unnecessary to locate nests or approach those that are very large or difficult to get close to (Landcare Research, 2007). However although most baits show some degree of attraction to wasps, bait attraction can vary between different sites and regions, weather conditions and within a population throughout the wasp flight season (Harris et al, 1991; Spurr, 1995; Wood et al., 2006 in Sackmann & Corley, 2007). This variation may be influenced by the presence of other food sources, nest requirements and behavioural traits. Protein rich foods and carbohydrates are generally attractive to foraging wasps, but relative attractiveness may vary throughout the season due to changing nest requirements (D’Adamo & Lozada, 2005). However there is no universal commercial bait for wasp control (Sackmann & Corley, 2007). In poison must be mixed with protein-based bait, as carbohydrate baits risk poisoning bees. However at certain times wasps are not greatly attracted to protein baits, which can cause poisoning operations to fail (Beggs, 2001). Toxins such as 1080, sulfluramid and fipronil mixed with sardine catfood can be effective at controlling wasps. Fipronil is faster acting and equally as toxic at concentrations 1000 times lower than sulfluramid. Fipronil was found to reduce colony activity of Vespula spp. By 99.7% in treated areas (Harris & Etheridge, 2001).

In NW Patagonia () Sackmann et al. (2001) found that beef baited with fipronil reduced wasp densities by 80-100%. Further studies by Sackmann and Corley (2007) found that the most attractive bait for V. germanica was beef. Honey and corn syrup did not attract foraging wasps as effectively, even when mixed with beef. The only effective insecticide was hydramethylnon 2% which reduced wasp populations by 54% after 72 hours. Although fipronil was more effective, the potential of to develop resistance to consistent use of one product may suggest the need for alternating use of insecticides in some situations (Sackmann & Corley, 2007).

Although poison baiting can kill 80-100% of the colonies within a site reinvasion is extremely likely (Beggs, 2001). Wasps have been recorded foraging up to 4km from their nest (Coch, 1972 in Beggs, 2001). Even if the controlled site was very large, queen wasps which can fly 30-70km to find suitable nesting sites are highly likely to invade the following spring.

Biological: Biological control has been used in attempts to achieve widespread control of wasps. Icheumonid parasitoids Sphecophaga vesparum vesparum, S. v. burra and Sphecophaga orientalis have been utilised as biological control agents for V. germanica (Donovan et al., 1989, 2002; Beggs & Harris, 2000; Beggs et al., 2002). For more information on biological control of wasps please follow this link.

A recent study in examined the pathogenicity of two entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae. It was determined that two strains of B. bassiana were pathogenic for workers and males of V. germanica reaching high mortality and sporulation percentages (Merino et al., 2007).

General Considerations: Some other general factors to consider: V. germanica constructs significantly larger nests in New Zealand (part of its introduced range) than it does in Europe; over-wintering of nests (i.e. re-using the same nest from one summer to the next) also occurs more frequently in New Zealand than in Europe (Fordham et al., 1991; Harris, 1996 in Ward et al., 2002). This suggests the wasp may be harder to control in areas of its introduced range.

Fordham et al. (1991) found that urban nests produced more workers and reproductive progeny (and had more combs per nest) compared to rural nests, a factor to consider when planning control strategies (Ward et al., 2002). Temperature variation may also affect the growth and impact of wasp colonies, for example, a slightly longer wasp-activity season exists in the warmer parts of (Sydney) than in the cooler parts (Melbourne, Hobart) (Ward et al. 2002).