Phenology of Stomoxyinae in a Kenyan forest

Abstract

The biology of nineteen taxa of African Stomoxyinae was studied during experiments with odour-baited Vavoua traps in Nairobi National Park, Kenya. Both male and female Stomoxys were captured in similar numbers with CO2 released at 2 l/min or octenol released at 2 mg/h. Some species of Haematobosca reacted synergistically to a combination of these attractants, producing large increases in catch. Stygeromyia and Rhinomusca responded only to CO2 and Prostomoxys did not respond to either bait. Many different activity patterns were documented in these genera, but most activity was concentrated just prior to sunset. For example, at peak densities nearly 1500 Stomoxyinae representing fourteen taxa were caught in a single trap between 18.00 and 19.00 hours. The Stomoxyinae community was exceptionally diverse when compared with other biting fly communities. Using data from traps set with different odour baits in the park forest, Shannon-Wiener diversity indices (H') varied from 2.5 to 2.8, and evenness (J') varied between 0.61 and 0.68. The Stomoxys population was extremely female-biased at the start of the rainy season, with species such as S. inornatus and S. boueti consisting of nearly 100% females. Sex ratios equalized when the first rainy-season generation emerged. population doubling times estimated from trap indices were approximately 12-16 days in two habitats (forest and riverine woodland).

Olfaction in vector-host interactions

“…Most of the test compounds did not affect trap catch, though 1-octen-3-ol yielded mixed results and sometimes was associated with increased (about 3-fold) catch, especially at high doses (2 mg/hr). In a similar study, Mihok et al (1996) did not find a consistent effect for 1-octen-3-ol. In two experiments it did not enhance catch of Stomoxys compared to CO 2 alone, and when released by itself caught less than half the number of flies as a CO 2 -baited trap, which is similar to the outcome for a CO 2 -baited Vavoua trap against an unbaited trap.…”

“…Hoy (1970) reported that Malaise traps releasing CO 2 at 3 l/min caught about three times more stable flies than unbaited traps, and Roberts (1972) reported that catches from a Malaise trap baited with 3.5 l/min CO 2 were similar to those from a trap baited with odour from a single steer. More recently, Mihok et al (1996) found that Vavoua traps baited with CO 2 at 2 l/min caught about twice as many Stomoxyinae flies as unbaited traps. Some of the early work on tsetse responses to odour also yielded useful information for Stomoxyinae.…”

Responses ofGlossina fuscipes fuscipes(Diptera: Glossinidae) and other Diptera to carbon dioxide in linear and dense forests

“…For example, catches of Tabanidae, Stomoxyinae and non-biting Muscidae were increased 7-20 times at 2.5 l min -1 and 38-47 times at 15 l min -1 in extensive electric net experiments with visual targets in Zimbabwe (Vale, 1980). Carbon dioxide can also act synergistically with attractants such as acetone and 1-octen-3-ol to produce large increases in catch for tsetse (Torr et al, 1995), and other Diptera (Mihok et al, 1996).…”

Phylogenetic analyses of mitochondrial and nuclear data in haematophagous flies support the paraphyly of the genus Stomoxys (Diptera: Muscidae)

“…Mavoungou et al (2008) described S. niger bilineatus and S. niger niger as sympatric species, the former being abundant in savannas with abundant wild fauna, while the latter is more associated with anthropized area. Mihok et al (1996) also pointed out differences in habitat affinities, sex ratio and activity patterns between these species. Given morphological observations, ecological isolation and molecular data, it appears very likely that S. niger niger and S. niger bilineatus belong to different species.…”