title: Experiences with population dynamics of Diabrotica virgifera virgifera LeConte in the Swiss canton of Ticino up to 2007.
abstract: The Western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a vexing alien invasive insect pest. It occupies the attention of entomologists in most countries of Europe and beyond. In spite of numerous research advances (e.g., Diabrotica symposium at Engelberg, Switzerland 2004) its behavior is still incompletely understood and cannot be predicted for a specific growing season with any degree of certainty. Nonetheless, by comparing several years in sequence a somewhat consistent and coherent picture is emerging that is subject of this contribution. The Ticino province received first beetles from the major infestation in Lombardy in 2000 across the geographically open border at Chiasso. The rapid advance of WCR in northerly direction along the river valleys of Ticino and Misox posed a threat to cantons north of the mountain chain of the Alps and beyond, a scenario outlined by Bertossa (2004), Wudtke et al. (2005) and subsequent papers. Following the Swiss Federal rule of crop rotation obligation around infested regions introduced in 2001, the rapid increase in population density leveled off. Careful monitoring by both Metcalf type pheromone and kairomone baited sticky traps and Hungarian traps provided a reliable tool for judging the success of any quarantine measures taken up until 2007. (1) Trends in population development of 2006 were confirmed. (2) However, for reasons not well understood, the overall population encountered in 2007 was significantly smaller in Ticino and neighboring areas of Lombardy, Italy, but also in other areas south of the Alps. This may be a consequence of the rather mild winter 2006-2007. (3) At the mountain pass of Monte Ceneri (some 600 m above sea level) no beetles were trapped in 2007, while 3 WCR were seen in 2006. (4) No new WCR were encountered in Swiss cantons north of the main chain of the Alps. (5) Metcalf sticky traps proved to be 4-5 times as sensitive as Hungarian traps used for comparison. By and large, mandatory crop rotation was beneficial in reducing WCR populations in Ticino and avoided or delayed northbound spread of WCR.
authors.affiliation: Agroscope Changins-Wädenswil ACW Centro Cadenazzo, CH-6594 Contone, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Bertossa
authors.forename: Hans E
authors.initials: HE
authors.lastname: Hummel
mesh_terms: D000818:Animals; D002980:Climate; D003058:Cockroaches / Q000187:drug effects / Q000472:pathogenicity*; D005843:Geography; D010675:Pheromones / Q000494:pharmacology; D011156:Population Density; D011157:Population Dynamics; D013557:Switzerland; D003313:Zea mays / Q000254:growth & development* / Q000469:parasitology*
chemical_list: D010675:Pheromones