Identification of Host Fruit Volatiles from Domestic Apple (Malus domestica), Native Black Hawthorn (Crataegus douglasii) and Introduced Ornamental Hawthorn (C. monogyna) Attractive to Rhagoletis pomonella Flies from the Western United States

Abstract

The apple maggot fly, Rhagoletis pomonella, infests apple (Malus domestica) and hawthorn species (most notably the downy hawthorn, Crataegus mollis) in the eastern USA. Evidence suggests that the fly was introduced into the western USA sometime in the last 60 years. In addition to apple, R. pomonella also infests two species of hawthorns in the western USA as major hosts: the native black hawthorn (C. douglasii) and the introduced ornamental English hawthorn, C. monogyna. Apple and downy hawthorn-origin flies in the eastern USA use volatile blends emitted from the surface of their respective ripening fruit to find and discriminate among host trees. To test whether the same is true for western flies, we used coupled gas chromatography and electroantennographic detection (GC-EAD) and developed a 7-component apple fruit blend for western apple-origin flies, an 8-component black hawthorn fruit blend for flies infesting C. douglasii, and a 9-component ornamental hawthorn blend for flies from C. monogyna. Crataegus douglasii and C. monogyna-origin flies showed similar levels of upwind directed flight to their respective natal synthetic fruit blends in flight tunnel assays compared to whole fruit adsorbent extracts, indicating that the blends contain all the behaviorally relevant fruit volatiles to induce maximal response levels. The black and ornamental hawthorn blends shared four compounds in common including 3-methylbutan-1-ol, which appears to be a key volatile for R. pomonella populations in the eastern, southern, and western USA that show a preference for fruit from different Crataegus species. However, the blends also differed from one another and from domesticated apple in several respects that make it possible that western R. pomonella flies behaviorally discriminate among fruit volatiles and form ecologically differentiated host races, as is the case for eastern apple and hawthorn flies.

Translating olfactomes into attractants: shared volatiles provide attractive bridges for polyphagy in fruit flies

“…; Cha et al . ). This is particularly enigmatic when optimal olfactory codes are disjunct and intermediate preferences suffer high fitness costs, such as in moth pheromone communication (Groot et al .…”

Ammonium Carbonate Is More Attractive Than Apple and Hawthorn Fruit Volatile Lures toRhagoletis pomonella(Diptera: Tephritidae) in Washington State

“…At the time this blend was tested, it was the most attractive of the newer apple blends in ßight tunnel behavioral assays (C.E.L., unpublished). The components of the other three new blends are described in Cha et al (2012). WA is the "WA3" in Cha et al (2012), the most attractive of Þve WA volatiles subsequently tested after MA in the ßight tunnel.…”

“…The components of the other three new blends are described in Cha et al (2012). WA is the "WA3" in Cha et al (2012), the most attractive of Þve WA volatiles subsequently tested after MA in the ßight tunnel. The two new hawthorn volatiles were the western ornamental hawthorn (OH) and western black hawthorn (BH) blends.…”

“…The two new hawthorn volatiles were the western ornamental hawthorn (OH) and western black hawthorn (BH) blends. OH is the "OH1" and BH is the "BH2" in Cha et al (2012), the most attractive of four ornamental hawthorn and seven black hawthorn blends, respectively, tested against western R. pomonella in ßight tunnel behavioral assays. Two additional previously developed volatiles were also tested in the study: the eastern apple (EA) and eastern downy hawthorn (EH) blends.…”

Pheromone races of Cydia splendana (Lepidoptera, Tortricidae) overlap in host plant association and geographic distribution

“…Plant volatile compounds play a key role in host choice and the colonization of new host plants in insect herbivores (Bengtsson et al, 2006;Bruce and Pickett, 2011;Cha et al, 2012) and host plant shifts have been associated with speciation events (Dres and Mallet, 2002;Servedio et al, 2011;Soto et al, 2012;Safran et al, 2013). Pheromone races in moths are sometimes associated with different host plants, for example in the European corn borer Ostrinia nubilalis (Leppik and Frerot, 2012;Unbehend et al, 2014).…”