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Ambrosia beetles in the cryptic species complex Euwallacea nr. fornicatus vector a fungal pathogen responsible for Fusarium dieback, a disease that impacts avocado (Persea americana), woody ornamentals, and numerous native trees in the USA (California, Florida), Israel, and other countries. Currently, these pests are detected with quercivorol lures (containing p-menth-2-en-1-ol isomers), but recent research identified an essential oil enriched in (-)-α-copaene as a new attractant. In this study, lure longevity and efficacy were assessed in three 12-week field tests conducted in Florida by deploying traps baited with quercivorol, α-copaene, and a combination of the two. A fourth test compared different formulations of quercivorol. Concurrent with field experiments, gas chromatographic analyses were conducted to quantify initial lure contents as well as volatile emissions from lures field-aged for 12 weeks. In all tests, the lure combination captured significantly more E. nr. fornicatus than the individual lures; and in two trials, synergistic attraction was observed. Field life of the combination lure was 12 weeks; longevity of single lures varied from 9 to 12 weeks. Twelve terpenoids were detected from the α-copaene-enriched oil, suggesting there may be additional attractants. Analysis of the quercivorol lure showed it contained 88% trans- and 9% cis-p-menth-2-en-1-ol. Results indicate that the combination of quercivorol and α-copaene provides a long-lasting, effective lure for early detection of E. nr. fornicatus in Florida. Further research is needed to determine which isomer of p-menth-2-en-1-ol is attractive to Florida E. nr. fornicatus, and if other members of the species complex are attracted to (-)-α-copaene. [ABSTRACT FROM AUTHOR]

The tea shot-hole borer, Euwallacea fornicatus Eichhoff, is an ambrosia beetle endemic to Asia and a pest of commercial tea, Camellia sinensis (L.) Kuntze. Recently, a complex of species morphologically similar to E. fornicatus has been recognized, which includes new pests established in Israel and the USA, both in California and Florida. Collectively termed E. nr. fornicatus, these cryptic species carry symbiotic Fusarium spp. fungi, some of which cause dieback disease in susceptible hosts, which include avocado, Persea americana Miller. Due to the threat to this economically important crop, research was initiated to evaluate efficacy of kairomone-based lures for detection of the beetle in Florida (termed the Florida tea shot hole borer, FL-TSHB). A series of field tests were conducted in 2016 in commercial avocado groves known to have FL-TSHB at various population levels. All tests evaluated lures containing quercivorol (p-menth-2-en-1-ol) and α-copaene, presented separately and in combination; and one test evaluated effect of trap type on beetle captures. In addition, electroantennography (EAG) was used to quantify female olfactory responses to lure emissions. This study identified (-)-α-copaene as a new attractant for FL-TSHB, equivalent in efficacy to quercivorol (the standard lure for Euwallacea detection in the USA); however, the combination of lures captured significantly more FL-TSHB than either lure alone. This combination resulted in synergistic attraction at two field sites and additive attraction at a third site. Sticky panel traps captured more FL-TSHB than comparably-baited Lindgren funnel traps. Females engaged in host-seeking flight from 11:00 to 16:00 hr (EST), with peak numbers observed between 12:00 and 13:00 hr. EAG analyses confirmed olfactory chemoreception of both kairomones, with a higher response elicited with the combination of volatiles. Results indicate that detection of pest E. nr. fornicatus in Florida can be improved by using a two-component lure consisting of p-menth-2-en-1-ol and (-)-α-copaene. [ABSTRACT FROM AUTHOR]

Members of a complex of cryptic species, that correspond morphologically to the ambrosia beetle Euwallacea fornicatus (Eichhoff) (Coleoptera: Curculionidae: Scolytinae), were recently found attacking avocado (Persea americana Mill.) in Israel and California. In early 2016, an outbreak of another member of this species complex was detected infesting approximately 1500 avocado trees in an avocado orchard at Homestead, Florida. An area-wide survey was conducted in commercial avocado groves of Miami-Dade County, Florida to determine the distribution and abundance of E. nr. fornicatus, to identify different populations of E. nr. fornicatus and their fungal associates, and to assess the extent of damage to avocado trees. Ewallacea nr. fornicatus were captured in 31 of the 33 sampled sites. A sample of 35 beetles from six different locations was identified as E. nr. fornicatus sp. #2, which is genetically distinct from the species causing damage in California and Israel. Eleven fungal associates were identified: an unknown Fusarium sp., AF-8, AF-6, Graphium euwallaceae, Acremonium sp. Acremonium morum, Acremonium masseei, Elaphocordyceps sp. and three yeast species. The unknown Fusarium isolates were the most abundant and frequently found fungus species associated with adult beetles and lesions surrounding the beetle galleries. In addition to fungal associates, three bacteria species were found associated with adult E. nr. fornicatus. Visual inspections detected significant damage in only two orchards. A large number of beetles were captured in locations with no apparent damage on the avocado trees suggesting that E. nr. fornicatus are associated with other host(s) outside the groves or with dead trees or branches inside the groves. More research is needed to determine the potential threat E. nr. fornicatus and its fungal associates pose to the avocado industry and agricultural and natural ecosystems in Florida. [ABSTRACT FROM AUTHOR]