Variation in the cuticular hydrocarbons of the Mexican fruit fly Anastrepha ludens males between strains and age classes.

In this study cuticular hydrocarbons (CHCs) were characterized from wings of individual unmated males of different Anastrepha ludens (Loew) mass-reared strains of different ages (3 and 19-day-old): (a) a standard mass-reared colony (control), (b) a genetic sexing strain, (c) a selected strain, (d) a hybrid strain, and (e) wild males. We found that the hydrocarbon profiles in all males included two n-alkanes, five monomethyl alkanes, and two alkenes. CHCs ranged from C26 to C31 . The most prominent peaks were 2-methyloctacosane (2-Me-C28), n-nonacosene (C29:1), 2-methyltriacontane (2-Me-C30), and n-hentriacontene (C31:1). Significant variations in the CHC amounts of the mass-reared strains were observed from Day 9 and thereafter. Comparison of CHCs using multivariate and canonical analyses across ages and among mass-reared strains and wild males revealed qualitative and quantitative differences. The relative amounts of C29:1 and 2-Me-C30 were significantly higher across age groups in the mass-reared strains than those in the wild males. In contrast, amounts of n-nonacosane (C29) significantly increased in wild males as they aged. Through statistical analyses, we inferred that CHC amounts vary with age. Wild males differed significantly from the mass-reared strains in the amount of C29, and the genetic sexing strain Tap-7 had significantly higher values for 2-methylhexacosane (2-Me-C26). In contrast the selected and control strain differed from the other strains in amounts of C29:1 and 2-Me-C30. We suggest that differential profiles in hydrocarbon composition among the strains may be mainly due to environmental pressures.

Sexual behavior and male volatile compounds in wild and mass-reared strains of the Mexican fruit fly Anastrepha ludens (Diptera: Tephritidae) held under different colony management regimes.

We compared the calling and mating behavior and volatile release of wild males Anastrepha ludens (Loew) with males from 4 mass-reared strains: (i) a standard mass-reared colony (control), (ii) a genetic sexing strain (Tap-7), (iii) a colony started from males selected on their survival and mating competitiveness abilities (selected), and (iv) a hybrid colony started by crossing wild males with control females. Selected and wild males were more competitive, achieving more matings under field cage conditions. Mass-reared strains showed higher percentages of pheromone calling males under field conditions except for Tap-7 males, which showed the highest percentages of pheromone calling males under laboratory cage conditions. For mature males of all strains, field-cage calling behavior increased during the last hour before sunset, with almost a 2 fold increase exhibited by wild males during the last half hour. The highest peak mating activity of the 4 mass-reared strains occurred 30 min earlier than for wild males. By means of solid phase microextraction (SPME) plus gas chromatography-mass spectrometry (GC-MS), the composition of volatiles released by males was analyzed and quantified. Wild males emitted significantly less amounts of (E,E)-α-farnesene but emitted significantly more amounts of (E,E)-suspensolide as they aged than mass-reared males. Within the 4 mass-reared strains, Tap-7 released significantly more amounts of (E,E)-α-farnesene and hybrid more of (E,E)-suspensolide. Differences in chemical composition could be explained by the intrinsic characteristics of the strains and the colony management regimes. Characterization of calling behavior and age changes of volatile composition between wild and mass-reared strains could explain the differences in mating competitiveness and may be useful for optimizing the sterile insect technique in A. ludens.