Courtship, mating, and ovarian development of the horn fly, Haematobia irritans irritans (L.)

Abstract

Courtship behavior of male and female horn flies was observed through use of 16-mm motion picture photography. Patterns of courtship were determined and categorized into elements of courtship. Horn fly courtship patterns consisted of continuum of ten elements: orientation, initial contact, mounting, prothoracic tarsal contact and movement, backward movement, genital orientation, genital contact, stretching of ovipositor and copulation. Receptive females only responded to the stimulatory cues of males. Unreceptive females may discontinue male courtship attempts by one of several rejection responses such as kicking at the male, moving to another resting place or failure to extrude her ovipositor. The importance of various appendage to horn fly mating activity was determined by surgical removal of each of the 3 pairs of legs, wings and/or antennae. Removal of the metathoracic legs from the male resulted in the most significant decrease in mating activity as measured by percentage of female insemination. Removal of female appendage did not result in any significant decrease in mating activity as determined by female insemination. A series of experiments were conducted to determine effects of age on horn fly mating activity. Populations of similarly aged male and female individuals were found to initiate mating activity as early as 34 h postemergence; greatest mating activity, as determined by percentage of female insemination, occurred 83 h postemergence. Male horn flies were found to initiate mating activity at 30 h postemergence, although females were not receptive to male mating activity until 42 h postemergence. Mating activity of male horn flies was not observed to be significantly affected by advanced age (14 days); however, a significant decrease in female insemination by 4-day-old, sexually mature males was observed to occur from days 11 through 14 postemergence. Male to female ratios of 1:1, 1:2, 1:3, 1:4, 1:5 and 1:10 were used to determine the number of female flies successfully inseminated by male horn flies. Statistically significant differences in percentage of insemination occurred at each of the above ratios following 4 and 12 h, respectively; however, no significant difference was found to occur between male and female ratios of 1:1 and 1:2 after 24 h...