Identification and Synthesis of Leptotriene, a Unique Sesquiterpene Hydrocarbon from Males of the Leaffooted Bugs Leptoglossus zonatus and L. occidentalis

Abstract

The leaffooted bugs Leptoglossus zonatus and L. occidentalis (Hemiptera: Coreidae) cause substantial damage in tree nut crops in North America and pine seed orchards in North America and Europe, respectively. Sexually mature males of both species produce a number of aldehydes, esters, and sesquiterpenes, which are hypothesized to constitute an aggregation pheromone attractive to both sexes. Among the volatiles produced by males of both species, we identified a unique sesquiterpene hydrocarbon, given the common name “leptotriene” (5), which elicited strong responses from antennae of both sexes in electroantennogram assays. Here, we report its structure and its synthesis from (−)-(E)-β-caryophyllene (1).

Labial Sensory Organs of Two Leptoglossus Species (Hemiptera: Coreidae): Their Morphology and Supposed Function

“…Leptoglossus is a large genus with 62 species characterised by flattened and dilated hind tibiae [ 3 ] (hence the common name “leaf-footed bugs” of the family Coreidae), and the ability to form aggregations with the help of pheromones [ 4 ]. They are all phytophagous with a wide range of specialisations, from feeding on a single genus to extreme polyphagy [ 3 ].…”

“…The genus Leptoglossus is neotropical in origin, with most species limited to Central and South America [ 5 , 6 ]. Some species (including both in this study) cause substantial damage to crops and orchards [ 4 ].…”

“…Over the last six decades, this species has significantly expanded its range to include eastern North America, Europe, Asia Minor, eastern Asia, northern Africa, and South America [ 8 , 9 ]. This species feeds on conifer cones and can be a major pest in conifer seed orchards [ 4 , 10 , 11 ]. In Europe, it is of particular concern to growers of edible pine nuts, Pinus pinea L. [ 12 ].…”

“…Leptoglossus zonatus (Dallas, 1852) [ 13 ] ( Figure 1 b), or the large-legged bug, is a polyphagous species widely distributed throughout the Americas. Leptoglossus zonatus is an important pest of a wide range of crops in the southern United States, including cotton, tomato, eggplant, almonds, pistachios, pomegranate, peach, citrus, watermelon, corn, and pecan [ 3 , 4 , 14 , 15 ].…”

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“…Leptotriene 6 is a sesquiterpene with a new skeleton from males of the leaffooted bugs Leptoglossus zonatus and L. occidentalis. 6 The structure and absolute conguration of leptotriene 6 was conrmed by synthesis from b-caryophyllene. The structures of the diterpenoids sinuscalide A 7 and sinuscatone A 8, from Sinularia scabra, were established by X-ray analyses.…”