Proceedings of the Fifth International Conference on Urban Pests
Chow-Yang Lee and William H. Robinson (editors), 2005.
Printed by Perniagaan Ph’ng @ P&Y Design Network, Malaysia.
Printed by Perniagaan Ph’ng @ P&Y Design Network, Malaysia.
Author
MICHAEL LENZ
CSIRO Entomology, GPO Box 1700, Canberra ACT 2601, Australia
Abstract A brief overview on the options for biological control of termites is presented. Many organisms have been identified as being able to kill termites. However, we do not know their real impact on field populations of termites. Research has focused on some entomopathogenic nematodes and the fungi Beauveria bassiana and Metarhizium anisopliae. Only a limited number of field studies have been conducted using both groups of organisms as control agents for termites. Work with M. anisopliae, notably from Australia, is discussed in more detail in this paper. Strains selected for field trials have to: be virulent; be able to tolerate temperatures above 30o C; pose no health threats to humans and higher animals; be easily mass produced; and have long-lived spores that are robust enough for easy formulation and storage. Spores from virulent isolates of M. anisopliae are repellent to termites and behavioural defence mechanisms by termites can limit the effectiveness of conidia applications. A number of options are available to formulate the spore product thus rendering it less repellent. Applications of conidia as inundative treatments to termite sites, or within an attractive bait matrix, are options for termite control with M. anisopliae. Microbial pathogens will solve certain termite problems but may not help with others. However, they have their place as one of the tools in integrated termite (pest) management.
Key Words Heterorhabditis, Metarhizium anisopliae, Beauveria bassiana, subterranean termites
INTRODUCTION
For many decades organochlorines formed the backbone of termite management worldwide. However, these pesticides were banned or withdrawn from the market for human health and environmental reasons from an increasing number of countries in the late eighties and the nineties. The move away from organochlorines is being further accelerated in recent years by efforts by the United Nations Environment Program (UNEP) and Food and Agriculture Organization (FAO) to eliminate globally the production and use of certain persistent organic pollutants (POPs) which include the organochlorine pesticides (UNEP/FAO/Global IPM Facility 2000). As a consequence of these developments, the focus in termite management has shifted increasingly to alternative methods in dealing with termite problems. Among the diversity of practiced and potential methods, the option of using biological control agents against termites continues to attract a great deal of attention. In this paper some of the issues in using such entomopathogens in termite management are discussed. Only two groups of organisms, nematodes and fungi have been investigated in the field to see whether they could cause an epizootic among termites. The main emphasis in this paper will be on fungi as termite control agents.
MICRO-ORGANISMS WITH AN IMPACT ON TERMITES
The literature contains numerous reports of organisms that may have potential to cause the death of termites. A partial review by Myles (2002a) lists 2 viruses, 5 bacteria, 17 fungi, 5 nematodes and 4 mites. The full list of such organisms is no doubt larger. Diseased termite colonies are rarely encountered in the field, although at any time even a healthy, vigorous termite colony will harbour some pathogenic organisms. However, sanitary measures within a colony, such as allogrooming, removing, entombing or feeding on cadavers, and the production of antibiotics ensure that disease outbreaks are kept in check. Only when colony vigour is weakened by age or chemical control measures, can epizootics readily develop and colonies may perish from diseases. Some of the modern termiticides are even known to act synergistically with soil micro-organisms to cause a more rapid decline in termite populations. For example, exposure of termites to sublethal doses of the insecticide imidacloprid triggers a high rate of fungal infestations in stressed termites, leading to a faster colony collapse than either agent could achieve on its own (Boucias et al., 1996; Neves and Alves, 1999; Zeck and Monke, 1992).
CSIRO Entomology, GPO Box 1700, Canberra ACT 2601, Australia
Abstract A brief overview on the options for biological control of termites is presented. Many organisms have been identified as being able to kill termites. However, we do not know their real impact on field populations of termites. Research has focused on some entomopathogenic nematodes and the fungi Beauveria bassiana and Metarhizium anisopliae. Only a limited number of field studies have been conducted using both groups of organisms as control agents for termites. Work with M. anisopliae, notably from Australia, is discussed in more detail in this paper. Strains selected for field trials have to: be virulent; be able to tolerate temperatures above 30o C; pose no health threats to humans and higher animals; be easily mass produced; and have long-lived spores that are robust enough for easy formulation and storage. Spores from virulent isolates of M. anisopliae are repellent to termites and behavioural defence mechanisms by termites can limit the effectiveness of conidia applications. A number of options are available to formulate the spore product thus rendering it less repellent. Applications of conidia as inundative treatments to termite sites, or within an attractive bait matrix, are options for termite control with M. anisopliae. Microbial pathogens will solve certain termite problems but may not help with others. However, they have their place as one of the tools in integrated termite (pest) management.
Key Words Heterorhabditis, Metarhizium anisopliae, Beauveria bassiana, subterranean termites
INTRODUCTION
For many decades organochlorines formed the backbone of termite management worldwide. However, these pesticides were banned or withdrawn from the market for human health and environmental reasons from an increasing number of countries in the late eighties and the nineties. The move away from organochlorines is being further accelerated in recent years by efforts by the United Nations Environment Program (UNEP) and Food and Agriculture Organization (FAO) to eliminate globally the production and use of certain persistent organic pollutants (POPs) which include the organochlorine pesticides (UNEP/FAO/Global IPM Facility 2000). As a consequence of these developments, the focus in termite management has shifted increasingly to alternative methods in dealing with termite problems. Among the diversity of practiced and potential methods, the option of using biological control agents against termites continues to attract a great deal of attention. In this paper some of the issues in using such entomopathogens in termite management are discussed. Only two groups of organisms, nematodes and fungi have been investigated in the field to see whether they could cause an epizootic among termites. The main emphasis in this paper will be on fungi as termite control agents.
MICRO-ORGANISMS WITH AN IMPACT ON TERMITES
The literature contains numerous reports of organisms that may have potential to cause the death of termites. A partial review by Myles (2002a) lists 2 viruses, 5 bacteria, 17 fungi, 5 nematodes and 4 mites. The full list of such organisms is no doubt larger. Diseased termite colonies are rarely encountered in the field, although at any time even a healthy, vigorous termite colony will harbour some pathogenic organisms. However, sanitary measures within a colony, such as allogrooming, removing, entombing or feeding on cadavers, and the production of antibiotics ensure that disease outbreaks are kept in check. Only when colony vigour is weakened by age or chemical control measures, can epizootics readily develop and colonies may perish from diseases. Some of the modern termiticides are even known to act synergistically with soil micro-organisms to cause a more rapid decline in termite populations. For example, exposure of termites to sublethal doses of the insecticide imidacloprid triggers a high rate of fungal infestations in stressed termites, leading to a faster colony collapse than either agent could achieve on its own (Boucias et al., 1996; Neves and Alves, 1999; Zeck and Monke, 1992).
For further details log on website :
http://www.icup.org.uk/reports%5Cicup008.pdf
No comments:
Post a Comment