BEHAVIOR AND INTERACTIONS OF WILD ANASTREPHA LUDENS (DIPTERA: TEPHRITIDAE) MALES ON A GRAPEFRUIT TREE

Authors: Robacker, David; Mangan, Robert; Moreno, Daniel; Tarshis Moreno, Aleena

Submitted to: Folia Entomologica Mexicana
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2003
Publication Date: 8/1/2003
Citation: Robacker, D.C., Mangan, R.L., Moreno, D.S., Tarshis Moreno, A.M. 2003. Behavior and interactions of wild anastrepha ludens (diptera: tephritidae) males on a grapefruit tree. Folia Entomologica Mexicana. 42(2):221-237.

Interpretive Summary: Reproductive behavior in the Tephritidae, an economically important family of fruit flies, has been recognized as an important factor in regulatory entomology. Behavior of tropical tephritids has been intensively studied because many of these species have a wide variety of host plants, are difficult to detect and are subject to quarantine. These species, including the Mediterranean fruit fly, the Mexican fruit fly, and the Caribbean fruit fly, have been studied for eradication programs by sterile insect release (SIR). SIR programs require that sterile males successfully copulate with wild females. This study was designed to identify the qualities of wild male Mexican fruit flies that enable successful courtship and copulation with wild females. Males were given identification tags and observed for a 27-day period on a caged, mature grapefruit tree so we could determine behavior of individual males and learn how it changed with age and experience with other males and with females. We found that the tendency of males to fight increases with age. Also, they attacked other males that were performing courtship displays, with increasing frequency and success as they aged. Results indicate that males that were able to enter and remain in male aggregations by displacing other males from the aggregations achieved greatest success at mating. This study identifies qualities of males important for mating success that can potentially be selected by geneticists to produce more competitive males for SIR. Also, gains in understanding of the mating system can be used to improve management of this pest in citrus and other host fruit orchards.

Technical Abstract: Behavior and interactions of individually identified wild male Mexican fruit flies were studied in a month-long mating-system study on a field-caged host tree. Males aggregated in groups of 2-6 on 26/27 observation days. The percentage of males observed calling increased with their age, but the percentage observed fighting did not increase. Aggregation, calling and fighting were not observed until 1.5 hours before dark, then reached maximum levels about the middle of the sexual activity period during the last 1.5 hours of daylight. Other behaviors that increased during this time were leaf changes and interactions with females. "Round-trip" flights in which males flew from and landed on the same leaf were observed only at this time. Aggregation size did not affect frequencies of calling or fighting. Leaf residents did not win more fights than intruders. However, the percentage of fights in which residents held territories increased during the sexual activity period (for days when females were present), but the intensity of fights (threats vs. physical contacts) did not change during this time. Males that won most of their fights fought more than weaker males and fought mostly among themselves. Weaker males also fought mostly with the dominant males. Male size affected neither fighting intensity, outcome of fights, nor tendency to fight as a resident or intruder, but larger males fought more often than smaller ones. Older males fought more often, fought with greater intensity, and were more successful as intruders than younger males. Males did not form dominance hierarchies based on the findings that the same males fought each other day after day with increasing frequency and intensity with age. Results contribute to general understanding of this and other species of Tephritidae.