Seed wasp invasions promoted by unregulated seed trade affect vegetal and animal biodiversity.

Cone and seed insects are considered the most important predators of tree seeds during the pre-dispersal phase of development. Among them, exotic seed chalcids in the genus Megastigmus invaded Europe as a result of the rapidly-increasing and mostly unregulated seed trade for afforestation and ornamental plantations. Unlike their economic impact in seed orchards, until recently, little attention was paid to the ecological impact of these insects. In the present study, selected case studies of alien Megastigmus spp. were considered to assess their specific impact on the potential of natural regeneration of native woody plants and on the native entomofauna competing for seed resource. We re-analyzed data from former studies that did not focus on these ecological interactions and, here, present previously unpublished results. Seeds of Douglas-fir, true cedars, true firs and wild roses were sampled all over Europe, and the relative importance of the native and invasive chalcid species was assessed as well as their specific impact on seed yield. In most cases, the recent arrival of alien chalcids resulted in a significant decrease in the regeneration potential of the host trees. In the absence of competitors, alien chalcids occupied the entire seed niche in Douglas-fir, but their impact tended to decrease after the arrival of invasive seed bugs. In firs, alien chalcids tended to displace the native chalcids, but not in wild roses and cedars, where their damage was increasing. Different biological traits that might explain invasive success of alien chalcids are discussed. However, no general invasive patterns seem to exist.

Emergence, trapping, and seasonal abundance of adult Cerambycidae (Coleoptera) associated with Cupressaceae in Connecticut.

Emergence, attraction to traps, and seasonal abundance of cerambycids (Coleoptera) whose larvae injure Cupressaceae were studied under natural conditions in southern Connecticut between 1999 and 2005. Adults of the Asian cerambycid Callidiellum rufipenne (Motschulsky) emerged from trunk sections of Thuja occidentalis L. between late March and mid-May. In contrast, the native Atimia confusa confusa (Say) emerged from trunk sections of Juniperus virginiana L. between late August and mid-October. Emerged adults of both cerambycids had a 1:1 sex ratio, and the emergence of Callidiellum rufipenne showed protandry. In a comparison of four trapping methods, sticky bands stapled to trap logs and dead trees of J. virginiana had the highest density of adults of A. confusa confusa and Callidiellum rufipenne. Based on adults trapped on sticky bands on trap logs, dead trees, or girdled trees of J. virginiana or T. occidentalis at different locations, Callidiellum rufipenne was active on hosts for 5-8 wk between April and June; Semanotus ligneus ligneus (Say) for 4 wk in April; Callidium frigidum Casey for 5 wk between early May and early June; and A. confusa confusa for approximately 12 wk between April and early July and again for 2-5 wk between September and late October. Catches of A. confusa confusa were significantly female-biased. Number of beetles captured usually was not correlated with the size of the sticky band on trap logs, cut trees, or girdled trees. This is the first quantitative study on emergence, trapping, and seasonal abundance of cerambycids associated with Cupressaceae in northeastern North America.

Distribution and hosts of Callidiellum rufipenne (Coleoptera: Cerambycidae), an asian cedar borer established in the eastern United States.

The distribution and hosts of the exotic cedar-boring beetle, Callidiellum rufipenne (Motschulsky) (Coleoptera: Cerambycidae), were determined in five northeastern U.S. states by capturing adults on cedar trap logs and by rearing adults from various conifers. This beetle was detected in the coastal states of Massachusetts, Rhode Island, Connecticut, New York, and New Jersey. In these states, adults emerged from the live or dead wood of four genera and eight species of Cupressaceae; species of Pinaceae were not hosts. Through its entire range, C. rufipenne is reported to infest at least 14 species of Cupressaceae, four species of Pinaceae, and one species of Taxaceae; but, records of Pinaceae and possibly Taxaceae are suspect. Based on the number of adults that emerged from coniferous poles in a five-way choice test in the field, the infestation level was significantly greater in Chamaecyparis thyoides (L.) Britton, Sterns, and Poggenburg and Juniperus virginiana L. than in Pinus rigida Miller, Pinus strobus L., and Tsuga canadensis (L.) Carribre (last three species uninfested). In a second test of host preference in the wild, beetles infested four cupressaceous species, but not Abies balsamea (L.) Miller, Picea rubens Sargent, Pinus rigida, P. strobus, and Ts. canadensis in the Pinaceae. Infestation level was highest in Ch. thyoides, followed in decreasing order by Juniperus communis L., Thuja occidentalis L., and J. virginiana. In a comparison of live and dead J. virginiana, beetles developed to adults only in dead trees (36 beetles per tree). When trunk sections of Th. occidentalis with and without bark were offered to females in cages, beetles of the next generation emerged exclusively from wood with bark. In the Northeast, only species of Cupressaceae apparently are suitable hosts for C. rufipenne. Infestation of these species may be prevented or reduced by proper care of live plants and by debarking trees after harvesting.