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Rural Industries Research & Development Corporation
Investigations into the management of the darkling beetle by TA Lambkin
November 2001
RIRDC Publication No 01/151 RIRDC Project No DAQ-244J
The darkling beetle, Alphitobius diaperinus (Panzer) is a common cosmopolitan insect pest of poultry houses, in particular broiler sheds and egg barns, and is capable of transmitting a large number of poultry diseases and parasites. In recent years industries have been concerned over increasing beetle numbers in broiler sheds and the pest’s potential to breach farm biosecurity. In spite of the occurrence of the pest on almost every Australian poultry farm, no previous Australian research has been undertaken to determine the pest’s behaviour and its insecticide resistance status. The researchers commenced investigation of these two areas of study in 1998, in particular to develop a better understanding of the ecology of the pest, and to determine if resistance to fenitrothion (Folithion®) and cyfluthrin (Tugon®) has developed in pest populations. Insecticide resistance in the pest was believed to be highly likely because of the long-term and frequent use of fenitrothion by industry, and because of continued control failures.
The main objectives of this research were to review the relevant literature pertaining to A. diaperinus research and thereby develop an improved understanding of the ecology of the pest, and also to develop an insecticide resistance testing method for A. diaperinus. These two objectives enabled a survey to be undertaken in southeast Queensland of broiler shed and egg barn beetle populations, and the subsequent testing of these populations for insecticide resistance.
The scientific literature review and project field studies have indicated that the pest’s ability to avoid contact with insecticides contributes to A. diaperinus control failures. This behaviour, together with predominantly clay-floors in most broiler sheds contributes to problems with control after clean-outs, as many individuals stay concealed in the floor and do not receive a lethal dose of insecticide. The development of a laboratory culture method has provided adequate numbers of test insects. Problems with the culture method have arisen during the latter part of the project due to mite infestations, and these have hindered the availability of insects for testing.
The development of fenitrothion and cyfluthrin resistance testing methods was successful. Test results showed that insects from SEQ broiler shed systems have strong fenitrothion resistance and some cyfluthrin resistance, and preliminary results indicate that populations of A. diaperinus from some production areas, for example Tamworth & the Atherton Tableland have quite weak fenitrothion resistance. Insecticide resistance levels in insects from other intensive livestock systems including egg barns were generally weaker, and all levels of resistance were directly related to duration and/or frequency of insecticide use. Insecticide resistance may not be the major factor that determines beetle population sizes in broiler sheds. There was no relationship between anecdotal estimates of broiler shed beetle numbers and fenitrothion and cyfluthrin resistance levels, ie- population sizes of insects in different broiler sheds, with similar levels of insecticide resistance, can be very different. Results of testing A. diaperinus from the only SEQ egg barn show that the insects were still susceptible to fenitrothion and a rotation of fenitrothion and cyfluthrin may be used on alternate clean outs. Whether these egg barn results are typical for all is not known. For broiler sheds in general it is suggested that the application of cyfluthrin be reduced to every second clean out (part or full) or just used over the summer period. This may delay the development of stronger resistance. Preliminary results for the broiler shed production areas of Tamworth & Atherton Tableland indicate that fenitrothion may be included with cyfluthrin in an insecticide rotation.
In summary, as development of strong insecticide resistance in all areas is inevitable given time, a closer examination is needed of the other major factors that control population sizes in broiler sheds.
When this is known, studies of currently registered insecticides, alternative control strategies and the interaction of both may be properly evaluated.
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