Tracking individual Bactrocera tryoni: Wind effects and natural movement

Authors: MOSES, ETHAN - Bridgewater College; LEHMAN, MEREDITH - Eastern Mennonite University; JOHNSON, ADESOLA - Eastern Mennonite University; WELTY PEACHEY, ALLYSEN - Eastern Mennonite University; YODER, JAMES - Eastern Mennonite University; DE FAVERI, STEFANO - Department Of Agriculture And Fisheries; CHEESMAN, JODIE - Department Of Agriculture And Fisheries; Manoukis, Nicholas; Siderhurst, Matthew

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2025
Publication Date: 4/30/2025
Citation: Moses, E.R., Lehman, M.G., Johnson, A.J., Welty Peachey, A.M., Yoder, J.M., De Faveri, S.G., Cheesman, J., Manoukis, N., Siderhurst, M.S. 2025. Tracking individual Bactrocera tryoni: Wind effects and natural movement. Entomologia Experimentalis et Applicata. 173(8):854-868. https://doi.org/10.1111/eea.13578.
DOI: https://doi.org/10.1111/eea.13578

Interpretive Summary: Fruit flies are major horticultural pests throughout the tropics and subtropics. Recent advances have made it possible to track individual fruit flies as they move around farms, urban areas, and other habitats. Tracking fruit flies allows us to better understand their biology and therefore how to better control them. For example, understanding how fruit flies move on farms will allow the optimization of trap placement or kill sprays. Information on how flies move in different environments under different conditions will allow more effective responses to pest fly invasions and outbreaks. This paper reports on how fruit flies move with the wind and their speed of movement in a papaya field. Data on flight behavior determined in this study provide parameters that may help enhance current surveillance, control, and eradication methods, such as optimizing trap placements and pesticide applications, determining release sites for parasitoids, and setting quarantine boundaries after incursions.

Technical Abstract: Determining the movement characteristics under real-world conditions of pest insects, such as tephritid fruit flies, is critical to increase the effectiveness of detection, response, and control strategies. In this study, we conducted two experiments using harmonic radar to track wild-caught male Queensland fruit flies (Qflies), Bactrocera tryoni, a major horticultural pest in Australia. In Experiment 1 we continuously tracked individual flies which were prodded to induce movement in a high-density papaya field. We conducted Experiment 2 in a field with lower papaya density and tracked flies were allowed to move without disturbance. This latter natural movement experiment showed that Qfly move at a rate of 19 ± 3 m/h. In both experiments, overall and between-tree flight directions were found to be correlated with wind direction while within-tree movement directions were not. Further, the effect of wind direction on fly trajectories varied by step-distance but not strongly with wind speed while step-distance distributions were consistent with Lévy walks. Qfly movements were well fitted by two-state hidden Markov models, further supporting the observation that Qflies move differently within (short steps with random direction) and between (longer more directional steps) trees. Data on flight directionality, step-distances, and movement speed determined in this study provide parameters that may help enhance current surveillance, control, and eradication methods, such as optimizing trap placements and pesticide applications, determining release sites for parasitoids, and setting quarantine boundaries after incursions.