Path Meander of Male Codling Moths (Cydia pomonella) Foraging for Sex Pheromone Plumes: Field Validation of a Novel Method for Quantifying Path Meander of Random Movers Developed Using Computer Simulations

Abstract

Measures of path meander are highly relevant to studies of optimal foraging by animals. However, directly recording paths of small animals such as insects can be difficult because of small size or crepuscular activity. Computer simulations of correlated random walkers demonstrated that the rates of decay in captures across a rectangular grid of traps when movers were released at its corner can be used to produce calibration curves for quantifying path meander indirectly. Simulations using spatial parameters matching those previously documented for male codling moths (Cydia pomonella (L.)) foraging for female pheromone plumes in the field predicted that meander, as measured in circular standard deviation (c.s.d.) of turn angles between track segments, should be ca. 50° and 30° when the target population density is high vs. low, respectively. Thus, if optimized, the mean value measured for C. pomonella populations encountering an unknown target density should fall between these limits. We recorded decay in C. pomonella catch across a 5 × 5 grid of pheromone-baited traps each separated by 15 m on 39 occasions where batches of ca. 800 males were released 10 m outside the corner of trapping grids arranged in five large Michigan apple orchards. This decay constant was translated into mean c.s.d value for path meander using the standard curve generated by the computer simulations. The measured decay constant for C. pomonella males was negative 0.99 ± 0.02 (S.E.M.), which translates to a path meander of 37 ± 2° c.s.d. Thus, the measured path meander of 37° fell between the 50° and 30° values optimal for dense and sparse populations, respectively. In addition to providing a rare documented example of optimal foraging for odor plumes, this research offers proof-of-concept for a novel approach to quantifying path meander of movers that could prove useful across diverse taxa.

Comparison of New Kairomone-Based Lures for Cydia pomonella (Lepidoptera: Tortricidae) in Italy and USA

“…The chemical ecology of the codling moth has been well investigated with several applications adopted by growers on a global scale for both monitoring and direct management [ 3 , 4 , 5 ]. The most important application has been the use of the female sex pheromone, ( E , E )-8,10-dodecadien-1-ol (PH), in lures to monitor male moth population dynamics [ 6 , 7 ], and within various dispensers, aerosols, and sprayable formulations for mating disruption (MD) [ 8 , 9 , 10 ]. Monitoring codling moth with PH lures within MD-treated orchards is challenging because male sexual behaviors are affected and moth captures in traps can be imprecise and variable [ 11 , 12 ].…”

Ants combine systematic meandering and correlated random walks when searching for unknown resources

“…‘Zig-zagging’ is a common behavior, observed mostly in insects. It is present, e.g., in flying insects approaching objects, 59 , 60 probably to gain spatial information about them, moths following a pheromone plume, 61 ants following a pheromone trail, 62 , 63 or ants visually navigating toward a goal location. 64 , 65 However, these examples are rather different from searching for resources of unknown locations in a gradient-free environment.…”

Simulating capture efficiency of pitfall traps based on sampling strategy and the movement of ground‐dwelling arthropods

“…The theory behind the trapping of ground‐dwelling arthropods moving randomly has been well developed (see e.g. Miller et al, 2015) and has often been tested and validated against empirical field studies (Adams et al, 2020; Bearup et al, 2016; Manoukis et al, 2014). Although numerical simulations provide a useful modelling framework, a key assumption in our study is that individuals are treated as homogeneous i.e.…”