Local spread of an exotic invader: using remote sensing and spatial analysis to document proliferation of the invasive Asian chestnut gall wasp

Remote sensing and spatial analysis represent useful tools for modeling species’ dispersal, characterizing the spread of invasions and the invasability of a region, and thus allowing more accurate predictions for developing mitigation strategies. American chestnut, Castanea dentata, was historically a dominant forest species in North America, but occurs only sporadically today after its functional elimination by an exotic fungal pathogen in the early 1900’s. In recent decades Castanea resources have increased due to restoration efforts, commercial chestnut plantations, and horticultural uses. This resurgence is threatened by an additional exotic species, the globally invasive Asian chestnut gall wasp, Dryocosmus kuriphilus. The gall wasp was first discovered in Lexington, Kentucky (USA) in 2010. We used remotely sensed data and Geographic Information Systems to describe the local distribution of the Castanea hosts, and the occurrence and dispersal of the gall wasp. We tested the hypotheses that geomorphology, Castanea occurrence, and prevailing winds influence local proliferation. We found that gall wasp spread may be attributable to host plant distribution and to the effects of prevailing winds occurring during a brief period of adult insect emergence, and is influenced by topography. Our results suggest that weather data and topographic features can be used to delineate currently infested areas and predict future gall wasp infestations

Captures of male European pine sawflies (Hymenoptera : Diprionidae) in pheromone-baited traps in Kentucky

Using sticky traps baited with (2S, 3S, 7S)-3,7-dimethyl-2-pentadecyl acetate, we assessed the seasonal and diurnal flight activity of the European pine sawfly, Neodiprion sertifer (Geoffrey), in Fayette, Madison, and Livingston counties in Kentucky. At each site, two replicates of individual sticky traps were baited and suspended about 1 m high and spaced at least 20 m apart. Trap catch was affected by site (P = 0.001). A total of 326 European pine sawfly males were captured at the Fayette Co. site during the period 18 September to 12 November, representing 7% of the season total. No males of this species were caught at the other sites. During peak flight activity (1 to 15 October), we monitored traps at 2.5-h intervals over 4 d to determine diurnal flight patterns. Flight activity began after 1100 h and ceased by 1830 h, and was significantly affected by time of day. European pine sawfly flight activity was greatest between 1330 and 1330 h. We captured over 5,200 male sawflies at all three sites, with peak activity occurring in May, July, September and October

Natural occurrence of Fusarium proliferatum on chestnut in Italy and its potential entomopathogenicity against the Asian chestnut gall wasp Dryocosmus kuriphilus

© 2014, Springer-Verlag Berlin Heidelberg. The Asian chestnut gall wasp Dryocosmus kuriphilus (DK) is one of the most important pests of chestnut trees worldwide, and sustainable control measures are urgently required for its control. In this study, the recurring mycoflora associated with DK galls in some Italian chestnut orchards was identified, and two Fusarium proliferatum strains (I3 and I4) were tested for their entomopathogenicity toward DK and their pathogenicity to chestnut in order to evaluate their potential as biocontrol agents. The two F. proliferatum strains, both isolated from the inside of DK galls and often covering dead bodies of larvae, pupae, and adults, caused a natural insect infection of about 4 % and resulted to be non-pathogenic to chestnut plants, while they induced 33 and 97 % of larvae mortality when applied in laboratory experiments to intact DK fresh or sectioned galls, respectively. Both strains infected maize seedlings, used as non-target hosts, and produced fumonisins in vitro. The efficacy in controlling DK in the galls, the absence of pathogenicity to chestnut, and the lower mycotoxin production indicated strain I3 as a promising biocontrol agent of the considered pest