Biocontrol potential of the entomogenous fungi Beauveria bassiana and Metarhizium anisopliae for tsetse flies (Glossina spp.) at developmental sites.

Spores of two entomogenous fungi, Beauveria bassiana and Metarhizium anisopliae, were mixed with sterile sand at two different concentrations (1.0 and 0.5 g/liter) and larvae of tsetse flies Glossina morsitans morsitans allowed to pupate in it, simulating field larviposition sites. One gram weight of B. bassiana-sand mixture was estimated to contain 1.4 x 10(6) spores/g and that of M. anisopliae-sand mixture 2.3 x 10(6) spores/g. Adult tsetse emerging from pupae in sand-spore mixtures suffered heavy mortalities 2-10 days postemergence. The highest mortality recorded at 1.0 g/liter was 97% for B. bassiana and 80% for M. anisopliae. Lower spore concentrations produced lower mortalities. Possibilities of biocontrol of tsetse in the field using mycopesticides at breeding sites are discussed.

Ixodid ticks (Acari: Ixodidae) and livestock production: effect of varying acaricide treatments on ticks and productivity in east coast fever-immunized weaner and dairy cattle.

In a pilot trial to evaluate cost-effective methods of acaricide application, east coast fever-immunized weaner and dairy cattle were subjected to varying tick control regimens. All experimental cattle were maintained under the same extensive system of management. Their monthly tick load, packed cell volumes, incidence of blood protozoans, weight changes, and daily milk production were noted. Apart from Rhipicephalus appendiculatus Neumann, other tick species found in the study site were R. pulchellus Gerstacker, Amblyomma gemma Donitz, Boophilus decoloratus Koch, and A. variegatum F. The control group under a weekly regimen of dipping had fewer ticks than each of the other groups for both weaner and dairy cattle. However, the percentage of increase in weight of the weaner cattle was least for the control group. The milk production of none of the groups was significantly different from that of the control group, although profit per animal for groups maintained under a monthly or six-weekly regimen of acaricide use was highest. The age of the experimental dairy cattle was found not to have any effect on their milk production. It is suggested that with successful immunization against east coast fever, both dairy and weaner cattle may be subjected to reduced dipping or spraying, the level of relaxation being dependent on the tick challenge. However, similar studies should be carried out in as many agroecological zones as possible using different breeds of cattle. Information on the level of acaricide residues in livestock products from different farming systems should also be generated. Only then can a definitive recommendation for a change from the present national intensive dipping policy be made.

Influence of exposure period and management methods on the effectiveness of chickens as predators of ticks infesting cattle.

Experiments undertaken on Rusinga Island, Kenya, indicated that Rhipicephalus appendiculatus (Neumann) was the predominant tick consumed on tick-infested cattle by chickens, followed by Amblyomma variegatum (Fabricius), Boophilus decoloratus (Koch) and Rhipicephalus evertsi evertsi (Neumann). The number of ticks consumed by chickens released with cattle in a 3 h release period was not significantly different from ticks consumed in a 4 h release period. In a free management system, chickens 1-3 months of age consumed more ticks than older ones; in a confined management system however, chickens 4-6 months of age consumed more ticks than younger birds. Although the numbers of ticks consumed by local and exotic breeds of chickens were not significantly different, a period of 8-10 weeks was necessary for the exotic breeds to become behaviorally adapted to tick predation on cattle. Local chickens bred in environments where cattle were absent took a shorter period of 4-6 weeks to adapt. It was concluded that the relatively large number of ticks consumed by each chicken during the 3 or 4 h release period is an indication that a good reduction of ticks on cattle can be achieved through tick predation by chickens. The preponderance of R. appendiculatus over other tick species consumed was a reflection of its relative abundance on cattle on the island rather than a selective preference for tick species.

Description and performance of an updraft trap for sandflies.

An updraft trap for sampling sandflies in the field was developed and tested in the Marigat area of Baringo District, Kenya. The main components of the trap were a 12 cm long plastic drain pipe, 9 V d.c. electric motor, aluminium fan and a perspex sandfly collection cage. Comparisons of the updraft trap with a CDC and a 1 x 1 m polythene sheet coated with castor oil (sticky trap) showed the former was more consistent than the other traps in sampling sandflies from animal burrows. A total of 1241 sandflies belonging to eleven species were collected. Sergentomyia bedfordi, Phlebotomus martini, S. antennatus and P. duboscqi were the commonest species comprising 32.5%, 27.0%, 21.1% and 11.3% of the total catch respectively. However, the relative proportion of the different species varied according to the type of trap used. The CDC trap apparently attracted the known vectors of leishmaniases in the area, P. martini and P. duboscqi. Significantly more male than female P. martini and S. antennatus were collected by the various traps. A significantly higher proportion of female S. bedfordi was captured by the updraft and sticky traps while equal numbers of male and female P. duboscqi were collected in all traps.