Vertical distribution and daily flight periodicity of ambrosia beetles (Coleoptera: Curculionidae) in Florida avocado orchards affected by laurel wilt

Authors: MENOCAL, OCTAVIO - University Of Florida; Kendra, Paul; Montgomery, Wayne; CRANE, JOHATHAN - University Of Florida; CARRILLO, DANIEL - University Of Florida

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2018
Publication Date: 6/1/2018
Citation: Menocal, O., Kendra, P.E., Montgomery, W.S., Crane, J., Carrillo, D. 2018. Vertical distribution and daily flight periodicity of ambrosia beetles (Coleoptera: Curculionidae) in Florida avocado orchards affected by laurel wilt. Journal of Economic Entomology. 111(3): 1190-1196.

Interpretive Summary: The invasive redbay ambrosia beetle carries a symbiotic fungus that causes laurel wilt, a deadly disease of U.S. trees in the laurel family, including commercial avocado (valued at $21 million in Florida for 2016). Recent studies indicate that the lethal fungus can be picked up by other ambrosia beetles that breed in trees with laurel wilt. Thus, there may be many secondary vectors of laurel wilt in south Florida avocado groves. Research was conducted by the USDA-ARS (Miami, FL) and the University of Florida (Homestead, FL) to determine the beetle species present, as well as their flight behavior, in Florida avocado groves with laurel wilt. A total of 12 species were detected, but six species made up 95% of the beetle community. Of those six, two species flew close to the ground, at the level of tree trunks, but the others were shown to fly at various levels, from the trunk up into the tree canopy. The majority of beetles initiated flight just before sunset, when light intensity and wind speed decreased. Information on flight height and flight period will aid scientists in developing effective control strategies for these pests, as well as direct decisions regarding the best time and location to target insecticide treatments. Targeted control reduces pesticide use, decreases costs, and minimizes environmental and safety concerns.

Technical Abstract: Ambrosia beetles have emerged as significant pests of avocado (Persea americana Miller) due to their association with pathogenic fungal symbionts, most notably Raffaelea lauricola, the causal agent of laurel wilt. We evaluated the interaction of ambrosia beetles with host avocado trees by documenting their flight height and daily periodicity in Florida orchards with laurel wilt. Flight height was assessed passively in three avocado orchards by using ladder-like arrays of unbaited sticky traps arranged at three levels (low: 0–2 m; middle: 2–4 m; high: 4–6 m). A total of 1,306 individuals of 12 species were intercepted, but six accounted for ~95% of the captures: Xyleborus volvulus, Xyleborinus saxesenii, Euplatypus parallelus, Xyleborus bispinatus, Xyleborus affinis, and Hypothenemus spp. (bark beetles). The primary vector of R. lauricola, Xyleborus glabratus, was not detected. Females of X. volvulus showed a preference for flight at the low level and X. bispinatus for the low and middle levels; however, captures of all other species were comparable at all heights. At a fourth orchard, a baiting method was used to document flight windows. Female X. saxesenii and Hypothenemus spp. were observed in flight 2-2.5 h prior to sunset; X. bispinatus, X. volvulus, and X. affinis initiated flight ~1 h before sunset; and X. crassiusculus at 30 min prior to sunset. Results suggest that ambrosia beetles in Florida have species-specific patterns in host-seeking flight, but the majority fly near sunset (when light intensity and wind speed decrease), and can fly much higher than previously assumed.