Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2014
Publication Date: 6/1/2014
Citation: Sappington, T.W., Burks, C.S. 2014. Patterns of flight behavior and capacity of unmated navel orangeworm adults (Lepidoptera: Pyralidae) related to age, gender, and wing size. Environmental Entomology. 43(3):696-705.
Interpretive Summary: The navel orangeworm is a serious pest in almond, pistachio, and walnut orchards. The potential distance this moth can travel from an infested to an uninfested orchard is not clear, and is a difficult problem to address experimentally. We used laboratory flight mills to examine the flight capacity of unmated males and females of different ages, and discovered that these small moths are capable of making quite long flights. Many of those we tested (> 20%) flew continuously for more than 5 hours, and several flew more than 9 hours without resting. Typical distances flown during a 10.5-hour night were between 7 and 15 km (4.5-9.5 miles), with females flying slightly greater distances and durations than males. In some species of moths, the size and shape of wings can affect the flight performance of an individual, but we found that variation in wing dimensions was not related to flight in the navel orangeworm. Whether moths make such long-distance and long-duration flights in the field is another question, but field data suggest they do, and our data indicate that they certainly have the physical ability to do so. This information will be used by university and government scientists to better understand patterns of dispersal for this insect, leading to better methods and strategies for pest management on both local and regional scales.
Technical Abstract: The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae) is a key pest of almond, pistachio, and walnut tree crops in California. Understanding dispersal of adults between orchards is important to improving management options. Laboratory flight behavior of unmated navel orangeworm of ages 1, 2, 3, 5, and 7 days post-eclosion was examined using flight mills. Variables measured included duration, distance, and speed of the longest uninterrupted flight, and the summed duration and distance of all flights. As a group, females flew farther and longer than males, but the differences were not great, and were not significant between sexes within age classes. Flight speed did not differ between sexes. Flight duration and distance did not differ with age, except that 7-d-old adults performed significantly more poorly for these parameters than did 1- and 2-d-old adults. Females began their flights about 1.5 h after the onset of dusk, and about 1.5 h earlier in the night than males. Flight capacity and propensity were substantial for both sexes and age classes. At least 20% of adults (except 7-d-old males) made a continuous flight > 5.5 hours, and median total distances flown during the 10.5-h night ranged from 7-15 km depending on age class. Surface area and length of forewings and hindwings were greater in females than males, but had little effect on flight performance. The results are generally consistent with field observations of navel orangeworm dispersal, but it will be important to characterize the effects of mating on flight, and flight on fecundity.