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Sexual Behavior and Pheromones of the European Hornet, Vespa crabro germana (Hymenoptera: vespidae)

1980; Kansas (Central States) Entomological Society; Volume: 53; Issue: 3 Linguagem: Inglês

1937-2353

Suzanne W. T. Batra,

Insect and Pesticide Research

The introduced European hornet, Vespa crabro germana Christ produces four probable pheromones: an aggrega tion pheromone from female feces, a defensive pheromone in ven om, a cephalic male territory marking pheromone, and a contact pheromone on thoraces of attractive queens that elicits copulatory behavior in males. Details of mating behavior, associates and dam age to trees and shrubs are included, with suggestions for use of attractant pheromone in traps for hornet control. The European hornet, Vespa crabro germana Christ, was first reported in North America (New York State) about 1840 (Shaw and Weidhaas, 1956). It has now spread throughout much of eastern North America, ranging from Ontario and Wisconsin to Alabama and Georgia. This wasp, which is much larger than the native Vespinae, commonly makes its carton nests in hollows in trees and posts, in sheds, barns and attics (Shaw and Weidhaas, 1956; Spradbery, 1973). The numerous large workers that nest in proximity to human habitation may seem alarming, but actual damage by this insect is usually limited to attacks on honey bees, the stripping of bark from living plants, and damage to ripe fruits. In Europe, this wasp is a nuisance when abundant near apiaries, where it kills honey bees for food (Matsuura and Sakagami, 1973). In Europe and the United States it strips the bark of living trees and plants such as oak, elm, lilac, birch, ash, horsechestnut, and dahlia obtain sap; small stems may be girdled and killed (Cory, 1931; Shaw and Weidhaas, 1956; Spradbery, 1973). Because there is surprisingly little in formation on the behavior of these conspicuous wasps, these brief notes are presented here. A large (about 1 x 1 m) nest was discovered in late September, 1978, by Dr. L. D. Owens of Greenbelt, MD. It was in the screened attic crawl space of his home, above the bedroom. This room had not been occupied during the previous month due to the stench from the nearby hornets' nest. This odor (see below) resembled the smell of a combination of dog feces, skunk Received for publication 13 April 1979. This content downloaded from 157.55.39.17 on Wed, 31 Aug 2016 04:11:08 UTC All use subject to http://about.jstor.org/terms 462 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY (Mephitis) anal gland secretion and badger (Taxidea) burrow. On October 6, workers were still bringing food to the nest, which consisted of masticated thoraces of yellow jackets and baldfaced hornets (Vespula spp.). Workers were also seen licking sap where they had stripped bark from lilac and fringe tree (Chionanthus virginica L.); Vespula spp. that were also licking sap at the stripped areas were lunged at, and captured by, the hornets. Hornets were entering the attic through a small hole in the screen next to the nest at a rate of 34 to 71 (Jc = 52) per ten minutes in mid-afternoon. Males were patrolling near the nest. According to Dr. Owens, the wasps were active at night and workers came to lighted windows. Several species of flies were entering and leaving the attic and walking on the nest envelope. They probably were attracted by the fetid nest odor and may have been feeding on wasp feces or detritus. Most abundant was the calliphorid, Phaenicia coeruleiviridis (Macquart); others were Calli phora vicina Robineau-Desvoidy; the muscids, Hydrotaea sp., Fannia can icularis (L.), Ophyra leucostoma (Wiedemann), Helina sp., Musca domes tica L. and the phorid, Dohrniphora cornuta (Bigot). Fannia canicularis is associated with V. crabro and Polistes spp. in Europe (Spradbery, 1973); in North America it occurs in nests of Vespula spp. where it feeds on wasp feces (MacDonald et al., 1974). The other flies listed above have not pre viously been reported in association with wasps. Vespula spp. workers were also attracted to the attic screen but were not allowed by guards to approach the nest. Fecal Attractant Pheromone Workers and some queens (but no males) had a fetid odor resembling the nest odor. This odor was readily detectable on all exterior parts of the body, and dry microdissection of about 50 living wasps revealed that it originated in the midgut. Midguts and rectums of these odorous wasps contained a strong-smelling amorphous dark brown substance. Young queens that were kept in cages on a diet of 4:1 sucrose/autolyzed yeast extract in water did not develop this odor and the pale midguts and rectums of 10 such dissected queens did not contain the brown material; the guts of 10 dissected males were similarly pale and odorless. According to Berman et al. (1966) the brown feces of larvae and adults of Vespa orientalis L. contain histamine and an inhibitory substance; possible gut pheromones or odors were not mentioned. On October 7, over 100 males and workers and one queen were caught during 24 hours in a large (1.0 x 0.5 x 0.5 m) screen funnel trap placed over the hole where wasps were entering and leaving the attic. This trap was taken to my backyard, about 1000 m from the nest. Escaping workers and males returned upwind to the trap and attempted to enter it. All wasps were removed from the trap for study and after three days the empty trap This content downloaded from 157.55.39.17 on Wed, 31 Aug 2016 04:11:08 UTC All use subject to http://about.jstor.org/terms VOLUME 53, NUMBER 3 463 Figs. 1-3. Vespa crabro germana. 1. Queen in defensive posture, exposing sting bearing venom droplet. 2. Male returning to nest, which is behind screen (arrow) at top of picture. 3. Caged males feeding on sugar-water and vitamin mixture. This content downloaded from 157.55.39.17 on Wed, 31 Aug 2016 04:11:08 UTC All use subject to http://about.jstor.org/terms 464 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY was replaced in my backyard. It retained the distinct odor of the hornet feces. Within two minutes one male came, and after about 15 minutes three males had flown upwind to the empty trap, where they alighted and rapidly walked about while antennating it; no males were seen elsewhere. When the empty trap was later placed 30 m from the nest, about 20 males flew upwind toward it, alighted and antennated it. They did not alight and an tennate other objects. The odor of the nest and bodies of females apparently serves as a general attractant or nest location pheromone, of particular value to a cavity-nesting species such as V. crabro germana. Patrolling males may seek nests (Fig. 2) for shelter and queens, as in V. mandarinia Smith (Matsuura and Sakagami, 1973). Males mated with both odorless and fetid smelling queens (see below). By October 16, all the workers had died, leav ing only young queens and males, and the nest odor had nearly disappeared.