Fleas are one of the major external parasites affecting free range chickens, causing irritation, tissue damage, blood loss and toxicosis which in turn affect quality and quantity of meat and egg production. There are many commercial insecticides available that are effective against fleas. These commercial insecticides have, however become expensive to most resourcelimited farmers and therefore unaffordable, causing farmers to seek low cost alternatives. This study was conducted to document, determine the existence of external parasites in freerange chickens and validate the alternative remedies used in controlling free-range chicken fleas by resource-limited farmers. A questionnaire survey was used to collect data on external parasites of free-range chickens and ethno-veterinary control remedies used by resourcelimited farmers to control these parasites at Amatola basin, in Eastern Cape, South Africa. Resource-limited farmers perceived that mites (79.6%), fleas (64.5%), lice (10.8%) and ticks (6.5%) were problematic parasites of chickens. To control these parasites, resource-limited farmers commonly use ash (28%) madubula (13% carbolic acid) (26.7%), Jeyes fluid (13% carbolic acid) (10%), paraffin (8.4%), used engine oil (2.8%), plants Tagetes minuta, Clutia pulchella, Calpurnia aurea (5.2%) and a few (4.2%) used commercial drugs Karbadust (Carbarly 5%) and mercaptothion 5%. About 7.5% of the respondents used neither of the remedies. To confirm the farmers’ perception on problematic external parasites of free-range chickens a diagnostic survey was conducted. Fifty free-range chickens were randomly selected and examined for external parasites. About 96% of the free-range chickens examined harboured at least one species of external parasites. Fleas (Echidnophaga gallinacea) (50.7%) were the most prevalent followed by lice, Menopon gallinae (12.4%); Menacanthus stramineus (5.3%) and Knemidocoptes mutans (0.57%). Given that Jeyes fluid, used engine oil, paraffin, C. aurea, C. pulchella and T. minuta were mainly used in controlling these parasites, it was important to determine the potential dermal irritant effects of these plants. A dermal irritant effect test was, therefore, conducted using a rat model. Forty eight rats, with parts of the backs shaven, were used to screen the materials for irritation. All the materials tested did not cause any visible skin irritation on rats (p>0.05). Regarding that ethnoveterinary materials were non irritant on rat skin in vitro repellency and contact bio-assay models were used to assess the insecticidal properties of Tagetes minuta, Calpurnia aurea, Clutia pulchella, used engine oil, paraffin and Jeyes fluid on fleas. For the in vitro bioassay T. minuta and Jeyes fluid at 100% concentration demonstrated a repellency level of 76 and 83%, respectively. Tagetes minuta was the most effective among plant materials (p<0.05). Clutia pulchella, C. aurea, used engine oil and paraffin showed insignificant repellency (p>0.05). For the contact bio-assay, C. pulchella, C. aurea and T. minuta at a concentration of 100% resulted in flea mortality of 83.5, 73.3 and 42.5%, respectively. The efficacy of Clutia pulchella compared well with that of Karbadust which had a mean mortality of 97.5%. Paraffin, used engine oil, and Jeyes fluid (19.2%) caused higher flea mortality of more than 82%. In the in vivo study 60 free-range chickens were artificially infested with fleas and test materials were topically applied on infested sites. Test materials exhibited varying flea load reduction efficacy. Used engine oil and Jeyes fluid at 76.8% concentration had a reduction efficacy of 100 and 96% after 3 days post application of test materials. These were not significantly different to that of the positive control Kabadust (carbaryl 5%). The plants C. pulchella and C aurea at 100% concentration had an efficacy of 92 and 77%, respectively. The commonly used remedies by resource-limited farmers to control fleas vary in efficacy. Some of the materials are as effective as the commercial insecticides hence they have a potential to be exploited as insecticides. Further investigations on plant compounds with insecticidal properties and their toxicity, need to be conducted before the plants are recommended for use.

Aerial control using 1080 (sodium monofluoroacetate) baits is widely used in New Zealand for the control of introduced brushtail possums (Trichosurus vulpecula), with the aim of protecting national conservation and agricultural values from these damaging pests. This thesis integrates research, completed over 25 years, that was motivated by growing recognition in the 1970s of the extent of possum impacts and the need to improve the effectiveness and efficiency of the control operation. Field research assessed the palatability of three types of cereal-based pellet baits and carrot baits in different regions, habitat types and seasons. Palatability was assessed by the consumption of the different bait types presented independently of each other on 15-30 plots, with rotation of bait types at plots on successive nights to provide equal exposure to each bait type. There was regional variation in possums' bait preferences, possibly reflecting genotypic differences, whereas seasonal variation was less evident. Carrot bait was preferred or equally preferred to cereal bait in 14 out of 20 field trials. The proportion of possums eating baits was then investigated by, firstly, developing a technique for tracing bait acceptance using rhodamine B, a UV-fluorescent dye. In four field trials, more than 95% of possums accepted three types of dye-marked bait, eliminating bait refusal as a major reason for low kills in winter control operations. In a fifth trial, conducted in summer, only 68% of possums accepted bait suggesting that seasonal availability of favoured foods may influence bait acceptance. Since possums must encounter baits before deciding whether to eat them, field studies were undertaken to assess the coverage achieved in normal aerial baiting operations. Large gaps, up to 400 m in width, were often found between baiting swaths; these could allow some possums to survive. A controlled field experiment, using acceptance of rhodamine-dyed bait as a measure of effectiveness, showed that bait distribution was least accurate where flight paths were not marked. Where gaps of 100 m between flight paths were deliberately created, bait acceptance was slower and less than where coverage was complete. Sowing baits at 3 kg/ha was as effective as at 10 kg/ha, indicating the potential for substantially reducing operational costs by using machinery capable of faultlessly distributing baits at low rates. Navigational guidance systems were evaluated and found to improve the accuracy of bait distribution. During 1993-1997, when a lower sowing rate of 5 kg/ha was adopted operationally by regional managers, control effectiveness was unchanged but annual savings of around $9 million accrued. Because of the lack of suitable sowing machinery, a bucket was developed to permit faultless distribution of baits at lower rates, demonstrating the possibility of yet further cost-savings. The possibility of seasonal food availability affecting bait acceptance was investigated in three different forest habitats. Dyed baits were aerially distributed on 100 ha at each site in each season over two years. In each trial, fat-based condition indices of possums were calculated and the abundance of possum-preferred plant foods described. Bait acceptance was consistently high (85-100%) in the 24 trials, and was not influenced by either condition or availability of preferred foods. It seems likely that seasonal variation in operational effectiveness is caused by either the availability of sharply seasonal, scarce foods that possums may feed on intensively for brief periods, or by warmer temperatures that render 1080 less effective. The influence of 1080 on acceptance of (rhodamine-dyed) baits was investigated in a field trial. Examination of possums for dye-marking showed that 25% of possums refused to eat either a lethal quantity of bait or any bait at all, compared with 98% of possums eating non-toxic bait. This indicated that 1080 is aversive to possums, which is a potential major reason for their surviving control operations. Pen trials were therefore conducted to further examine the problem and to seek solutions. Toxic carrot baits were rejected by 27.5% of possums, equally by smell and taste aversion, whereas toxic cereal pellets were rejected by 34%, mainly by taste aversion. Orange and cinnamon were shown to be among the most preferred of 42 flavours tested and, when applied to toxic baits, 1080 was effectively masked. Bait refusal was reduced to ≤7%, the same as that recorded for possums presented with flavoured non-toxic baits. For long-term control of possum populations, aerial 1080 baiting can be used sequentially with other poisoning methods. However, the compatibility of these methods is dependent on the likelihood of possums developing bait shyness if sublethally dosed. Studies were therefore conducted to characterise and compare the four main toxicants used (1080, cyanide, cholecalciferol and brodifacoum) for induction and mitigation of bait shyness. Shyness was induced in approximately 80% of possums sublethally dosed with cyanide, 60% with 1080, 20% with cholecalciferol, and 0% with brodifacoum. Cyanide and 1080 shyness were found to persist in many possums for at least 12 and 24 months, respectively. Use of alternative bait types, and of baits containing an alternative slow-acting toxin (brodifacoum) were shown to be effective ways of overcoming shyness. This, and other related research, is reviewed to provide operational specifications that maximise the likelihood that all targeted possums will (i) encounter bait, (ii) eat it, and (iii) die. The likely future use of aerial 1080 baiting is described and the technological, economic, environmental and social constraints on its sustainability are discussed. Finally, the uptake of the research by possum managers is considered, and areas identified in the thesis where information is incomplete are summarised as prioritised topics for further research.