Breeding performance and longevity of Tomicus destruens on Mediterranean and continental pine species

The pine shoot beetle Tomicus destruens (Wollaston) (Coleoptera: Curculionidae: Scolytinae) is one of the main pests of Mediterranean forests, where it is oligophagous on Mediterranean pines. However, possible global warming may make the insect move to higher latitudes and altitudes, allowing it to attack new pine species. In this respect, the aim of the present article was to assess both the acceptance and performance of T destruens offered host and non-host pine species. A no-choice breeding experiment was set up under laboratory conditions, using logs of three Mediterranean (Pinus pinea L., Pinus pinaster Miller, and Pinus halepensis Aiton) and two continental (Pinus nigra Arnold and Pinus sylvcstris L.) pine species. Log debarking at the end of adult emergence assessed parent fecundity egg, and larval mortality. The quality of callow adults emerging from each tested pine was evaluated on the basis of their longevity on a semiartificial diet. Tomicus destruens colonised all tested pine species, but did not reproduce in Scots pine, taking about 79 days to complete development with no differences among pines tested. The best breeding performance, evaluated as female fecundity and adult production, was observed in R halepensis, and the lowest in P. pinaster. On average, adults emerging from P. pinea survived longer (83 days) than from other pines, and adult longevity was the lowest in males emerging from R nigra. Austrian pine, which under natural conditions is usually not a host of T. destruens, allowed insect development and adult production similar to P. pinea and P. pinaster.