Aggregation Behavior and a Putative Aggregation Pheromone in Sugar Beet Root Maggot Flies (Diptera: Ulidiidae)

Abstract

Male-biased aggregations of sugar beet root maggot, Tetanops myopaeformis (Röder) (Diptera: Ulidiidae), flies were observed on utility poles near sugar beet (Beta vulgaris L. [Chenopodiaceae]) fields in southern Idaho; this contrasts with the approximately equal sex ratio typically observed within fields. Peak observation of mating pairs coincided with peak diurnal abundance of flies. Volatiles released by individual male and female flies were sampled from 08:00 to 24:00 hours in the laboratory using solid-phase microextraction and analyzed using gas chromatography/mass spectrometry (GC/MS). Eleven compounds were uniquely detected from males. Three of these compounds (2-undecanol, 2-decanol, and sec-nonyl acetate) were detected in greater quantities during 12:00–24:00 hours than during 08:00–12:00 hours. The remaining eight compounds uniquely detected from males did not exhibit temporal trends in release. Both sexes produced 2-nonanol, but males produced substantially higher (ca. 80-fold) concentrations of this compound than females, again peaking after 12:00 hours. The temporal synchrony among male aggregation behavior, peak mating rates, and release of certain volatile compounds by males suggest that T. myopaeformis flies exhibit lekking behavior and produce an associated pheromone. Field assays using synthetic blends of the putative aggregation pheromone showed evidence of attraction in both females and males.

Optimizing a pheromone lure for the sugar beet root maggot fly, Tetanops myopaeformis

“…These fields were managed according to standard agronomic practices as recommended by The Amalgamated Sugar Company (Anonymous, 2019); these included insecticide applications targeting sugar beet root maggot larvae and adults based on action thresholds. The various pheromone blends tested were made using commercially available compounds previously identified from males, using the trap design and methodology previously described in detail by Wenninger et al (2017). Briefly, a white sticky card (76 × 127 mm; Great Lakes IPM, Vestaburg, MI, USA) was clipped to a wooden stake (30 cm long × 2.9 cm wide × 0.3 cm thick) using a binder clip, and the pheromone was dispensed onto a cotton dental wick (8 mm diameter, 38 mm long) that was inserted into a hole ca.…”

“…This experiment was designed to clarify whether all compounds used in our previous lure (Wenninger et al, 2017) were necessary to observe attraction of flies. In particular, we sought to determine the relative importance of the major compound [( R )‐(−)‐2‐nonanol] and the minor compounds, and whether the major compound might be sufficiently attractive on its own.…”

“…The 10‐compound blend was based on a blend that was used previously (Wenninger et al, 2017) but also included 2‐undecanol, a male‐specific compound that was not available for purchase during our previous trials. The 10‐compound lure comprised the following compounds totaling 16.6 mg per lure in the following proportions, based on their proportions in volatiles detected from male flies with solid phase microextraction SPME: ( R )‐(−)‐2‐nonanol (93.7%), 2‐nonanone (2.4%), dodecanal (1.2%), 1‐nonanol (0.96%), 6,10‐dimethyl‐5,9‐undecadien‐2‐one (0.84%), 2‐dodecanol (0.24%), 2‐undecanol (0.24%), decanal (0.18%), 2‐decanol (0.12%), and undecanal (0.12%).…”

“…We recently identified a putative aggregation pheromone in T. myopaeformis that is attractive to adults of both sexes (Wenninger et al, 2017), providing an opportunity to greatly improve the efficiency of monitoring traps and possibly to develop other pheromone‐based management tools. For example, pheromone‐based attract‐and‐kill and mass trapping have been pursued in other flies within the superfamily Tephritoidea, including the Caribbean fruit fly, Anastrepha suspensa (Loew) (Nation, 1989; Heath et al, 1993) and the olive fruit fly, Bactrocera oleae (Rossi) (formerly Dacus oleae ) (Haniotakis et al, 1991).…”

“…The pheromone lure that we tested previously for T. myopaeformis comprised a nine‐compound blend of volatiles identified from males, including the ( R ) enantiomer of the major component, 2‐nonanol (Wenninger et al, 2017). Although an effective attractant, a lure based on this blend would be prohibitively expensive for monitoring or management of T. myopaeformis given the number of compounds and the high cost of using a single enantiomer.…”