4‐allylanisole as a lure adjuvant for Dendroctonus frontalis (Coleoptera: Curculionidae: Scolytinae) and two associated beetles

Abstract

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae), is a major pine tree killer in North and Central America. In the southeastern USA, responses by D. frontalis to its aggregation pheromone can be substantially increased by at least three host odours: the monoterpenes alpha‐ and beta‐pinene, and the phenylpropanoid 4‐allylanisole. We executed three trapping experiments to assess the influence of 4‐allylanisole release rate on aggregation behaviour of D. frontalis and to evaluate the compound as an adjuvant for the operational monitoring lure for D. frontalis. Addition of devices releasing 4‐allylanisole at any of three rates (4.8, 48, and 500 mg/day measured at mean 21°C) increased D. frontalis attraction to a pheromone lure, both in the presence and in the absence of an alpha‐pinene lure. The increase was 5‐ to 50‐fold with a positive dose response up to the highest tested release rate of 4‐allylanisole. Attraction of an associate, the black turpentine beetle, Dendroctonus terebrans (Olivier), and a major D. frontalis predator, Thanasimus dubius (F.) (Coleoptera: Cleridae), was also significantly increased by 4‐allylanisole. A device releasing 4‐allylanisole at 0.05 g/day (at mean 23°C) increased attraction of D. frontalis to the current operational monitoring lure (which uses alpha‐ and beta‐pinene as the host odour component) approximately 4‐fold, but it did not increase attraction to a lure with turpentine as the host odour component (used in a former operational monitoring lure). Additionally, we observed none of the attraction‐inhibiting effects that were previously reported for 4‐allylanisole with D. frontalis. It is possible that the addition of 4‐allylanisole to the D. frontalis lure might allow detection of beetles at lower population densities and, if so, aid in earlier detection of populations invading the northeastern USA in response to climate change. This possibility should receive further investigation.

The Use of High-Resolution Satellite Imagery to Determine the Status of a Large-Scale Outbreak of Southern Pine Beetle

“…Given the spread of SPB further north [23], out of the southeastern United States, other regions will need to begin a means of assessing their presence and impacts on forested areas [7]. This could be a combination of field-based monitoring/trapping [6] and remotely sensed techniques like that covered here and with other sensors. Future research should consider forest density relationships with changes in spectral reflectance, particularly infrared portions of the spectrum commonly associated with healthy vegetation.…”

“…Insect monitoring and detection efforts help to determine counts and insect sex ratios that may preclude an outbreak [6,7]. Once started, SPB outbreaks can be difficult to manage.…”

Composition of Attractant Semiochemicals of North American Species of Dendroctonus Bark Beetles: A Review

“…(+)-alpha-Pinene enhances attraction more than the (−)-enantiomer, but not more than the racemate [246]. A minor constituent of the resin of host pines for D. frontalis, 4-allylanisole, increased attraction to a pheromone component combination (frontalin and exoand endo-brevicomin) in a positive dose-dependent manner when released at approximately 5 to 500 mg/d (causing up to a 50-fold catch increase), with or without alpha-pinene also present [165]. These results contrast with some studies which have reported 4-allylanisole to have repellant and attraction-inhibiting activity [257,258].…”

“…Two oxygenated monoterpenes without a known natural origin relevant to D. terebrans biology, 1,4-cineole and eucalyptol, increased attraction to the bicyclic ketal combination with or without alpha-pinene also present [244]. 4-Allylanisole released from approximately 5 to 500 mg/d enhanced attraction to the combination of the ternary bicyclic ketal combination and alpha-pinene in a positive dose-dependent manner [165].…”

“…Effects of attractive bark beetle semiochemicals are typically dose-dependent, often displaying increasing trap catches with increasing release rates within the limited range of rates typically tested in experiments [79,[164][165][166]. The term "multifunctional" has been used for bark beetle semiochemicals that exhibit attractive effects when released at relatively low rates but attraction-reducing or repellant effects at high rates [167][168][169][170].…”