Non-chemical control of the Red-billed Quelea (Quelea Quelea) and use of the birds as a food resource

The Red-billed Quelea Quelea quelea is the most numerous terrestrial bird and the most destructive avian pest of small-grain crops throughout sub-Saharan Africa. The birds occur in 60% of the cereal production areas of Tanzania almost every year. Quelea can cause serious local damage to millet, rice, wheat and sorghum and cause considerable hardship to subsistence farmers. Spraying with the organophosphate avicide Queletox®, (60% fenthion a.i.) remains the preferred control measure despite its negative impact on the environment and high cost. As an alternative control measure, the mass trapping of quelea and harvesting their chicks to use both as a source of protein and for income generation was investigated. Two traps using very large nets, based on designs used successfully to catch birds in Tunisia and the USA, failed with quelea; but success was achieved with four other methods. With traditional basket traps made of grass, an average of 286 birds could be caught per trap per day, this increased to 574 birds by using a replica wire mesh version. When using mist nets in a breeding colony the number of birds caught per day per 12 m long net varied from 445 for the first day to 231 on the tenth day. Trials with a roost trap yielded 5,000 to 17,000 birds per day. Cooking and preservation methods were investigated to maximise the potential utilization of quelea meat as a food resource. The best preservation method was achieved by boiling with added salt and drying, while the cooked product rated most highly by volunteer tasters was fresh meat. Proximate analysis was conducted on preserved, milled, quelea meat which confirmed the highly nutritive value of quelea for human consumption. It was concluded that mass-trapping and chick harvesting methods were more environmentally friendly control methods than spraying or use of explosives, with the added benefits of providing high-quality proteinaceous, uncontaminated, food and income generation for the trappers and their families

Alternative approaches to Red-billed Quelea Quelea quelea management: mass-capture for food

Organophosphate pesticide spraying or the deployment of explosives as standard practices for controlling quelea breeding colonies or roosts that threaten small-grain crops in Africa have negative side-effects on non-target birds and on the environment. Mass-capture techniques were tested as an environmentally more friendly alternative. The birds caught could be used as food for local people. Traditional capture methods were also evaluated with a view to improving them. Large funnel traps, with and without bright lights, gave poor results because the behaviour of quelea and the thorny habitat made it difficult to drive the birds into the trap after dark. Locally made mist-nets functioned well. They allowed thousands of quelea to be caught. After a few days, parts of colonies where trapping had taken place were abandoned, and farmers reported a considerable reduction in the numbers of quelea raiding their fields. The proportion of non-target birds caught in the nets was very low and many were released unharmed. Catches were monitored by officials to ensure that only quelea were taken. With further refinement and the establishment of proper regulation, the use of mist-nets to control quelea colonies or roosts seems likely to be a viable alternative to aerial spraying of pesticides

Effects of the organophosphate fenthion for control of the red-billed quelea Quelea quelea on cholinesterase and haemoglobin concentrations in the blood of target and non-target birds

The red-billed quelea bird Quelea quelea is one of sub-Saharan Africa’s most damaging pests, attacking small-grain crops throughout semi-arid zones. It is routinely controlled by spraying its breeding colonies and roosts with organophosphate pesticides, actions often associated with detrimental effects on non-target organisms. Attributions of mortality and morbidity of non-targets to the sprays are difficult to confirm unequivocally but can be achieved by assessing depressions in cholinesterase activities since these are reduced by exposure to organophosphates. Here we report on surveys of birds caught before and after sprays that were examined for their blood cholinesterase activities to assess the extent to which these became depressed. Blood samples from birds were taken before and after sprays with fenthion against red-billed quelea in colonies or roosts, and at other unsprayed sites, in Botswana and Tanzania and analysed for levels of haemoglobin (Hb) and activities of whole blood acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Background activities of AChE, BChE and Hb concentrations varied with bird species, subspecies, mass, age and gender. Contrary to expectation, since avian erythrocytes are often reported to lack cholinesterases, acetylcholinesterase activities in pre-spray samples of adult birds were positively correlated with Hb concentrations. When these factors were taken into account there were highly significant declines (P\0.0001) in AChE and BChE and increases in Hb after contact with fenthion in both target and non-target birds. BChE generally declined further (up to 87 % depression) from baseline levels than AChE (up to 83 % depression) but did so at a slower rate in a sample of quelea nestlings. Baseline activities of AChE and BChE and levels of Hb were higher in the East African subspecies of the red-billed quelea Q. q. aethiopica than in the southern African subspecies Q. q. lathamii, with the exception of BChE activities for adult males which were equivalent

Soil contamination and persistence of pollutants following organophosphate sprays and explosions to control red-billed quelea (Quelea quelea)

BACKGROUND: Red-billed quelea (Quelea quelea) are controlled at breeding colonies and roosts by organophosphate sprays or explosions. Contamination with organophosphates after sprays and with petroleum products and phthalates after explosions was assessed. RESULTS: Concentrations in soil of the organophosphate fenthion the day after sprays were uneven (0–29.5 μg g−1), which was attributable to excess depositions at vehicle turning points, incorrect positioning of nozzles and poor equipmentmaintenance. A laboratory study using field-collected samples provided an estimate of 47 days for the half-life of fenthion. After sprays,fenthion persisted in soil for up to 188 days. High concentrations were detected 5 months after negative results at the same sites, providing indirect evidence of leaching. Concentrations of total petroleum hydrocarbons (TPHs) and phthalates ranged from 0.05 to 130.81 (mean 18.69) μg g−1 and from 0 to 1.62 (mean 0.55) μg g−1 respectively in the craters formed by the explosions, but declined to means of 0.753 and 0.027 μg g−1 at 10m away. One year after an explosion, mean TPHs of 0.865 and mean phthalates of 0.609 were detected. CONCLUSION: Localisation of high concentrations of fenthion likely to have effects on soil biota could be mitigated by improved spray management. Given a half-life in the soil of 47 days for fenthion and the possibility of its leaching months after applications raises concerns about its acceptability. The pollutants left behind after explosions have been quantified for the first time, and, given their long-term persistence, their continued use poses a threat to environmental health