www.kleine-wesen.org
www.kleine-wesen.org
Isodontia mexicana, the Mexican grass-carrying wasp, is a species of insect belonging to the family Sphecidae. It is mainly found throughout North America, but has become established in Europe, primarily France, Switzerland, Hungary, Italy, Serbia, and Spain. The adults grow up to 18–20 millimetres (0.71–0.79 in) long, the body is completely black, the thorax is quite hairy and the wings have a smoky-brown color. They can be encountered from early Summer through September. Females are larger and emerge as adults later in the season than males. Isodontia mexicana is a typical case of a species arrived accidentally from North America and slowly encroaching on the European continent, probably for the lack of predators or parasites. These wasps build their nests in hollowed branches or in other natural cavities, often reusing the nests of other species. Then they line the inside with grass fragments or other plant fibers (hence the name of ‘Grass-carrying wasps’). I. mexicana mainly preys on grasshoppers (usually katydids, Tettigoniidae species) or Tree crickets (Gryllidae species), choosing the small ones and carrying them to its nest to feed the emerging larvae with the living, but paralyzed Orthoptera.
The grass-carrying wasp Isodontia mexicana (Saussure) exhibits interesting behaviors related to sex allocation, nest construction, and prey selection. Females of this species exhibit facultative sex allocation, meaning they can adjust the sex ratio of their offspring depending on certain factors. The wasps construct nests from grass stems, lining them with glandular secretions for protection against pathogens. They also provision their nests with paralyzed insects as food for their developing offspring. The effects of brood parasitism on Isodontia mexicana have been studied, revealing that it can have sublethal effects on the wasps' reproduction and survival. In some regions, the species has been introduced adventitiously, like in Piedmont, Italy.
Der Stahlblaue Grillenjäger (Isodontia mexicana) ist eine Grabwespe aus der Familie Sphecidae.
Isodontia mexicana ist eine Grabwespe mit einer Körperlänge von 15 bis 20 mm. Sie hat eine schwarze Körperfarbe, rauchige schwarze Flügel mit auffälligem Blauschimmer und eine mit Borsten bedeckte Kopfvorderseite. Die Art stammt ursprünglich aus Mittel- und Nordamerika und wurde in den 1960er Jahren nach Südfrankreich eingeschleppt. Seitdem hat sie sich über große Teile Südeuropas ausgebreitet, ist aber auch in Deutschland lückenhaft verbreitet. Die Wespen legen ihre Nester in oberirdischen Hohlräumen an und jagen Blumengrillen und Schwertschrecken.