Repellents, beetle

Dolichodial Teuerium marum (Lamiaceae) Insect repellant beetle... 

What chemistry is used by bombardier beetles to repel predators ... 

A detailed predator-prey analysis of the chemical relations between the carabid Pasimachus subsulcatus and the skink Eumeces inexpectus proved that the latter were repelled by constituents of the carabids secretions, indicating that the beetles are chemically protected from attacks by the lizards [85]. 

When disturbed or molested, these insects release small droplets of hemo-lymph from the tibio-femoral joints of their legs, and it is now well established that the deterrency exhibited by many species of coccinellids towards potential predators results from the presence of repellent and bitter alkaloids in that fluid [ 12,13]. In ladybirds, this unpalatability is associated with a bright aposematic coloration and a characteristic smell due to 3-alkyl-2-methoxypyrazines [14, 15]. The beetles use these molecules not only to reinforce the visual alerting signal on an olfactory level, but also as aggregation pheromones [16]. 

In insect control, PEA has been considered as a mosquito repellant (68), and its acetate has been used as an ingredient in Japanese beetle bait (69). The alcohol also has bacteriostatic action and antifungicidal properties (70—73), and it has been claimed as a surface-active agent (74). 

Kohnle U., Densbom S., Duhme D. and Vite J. P. (1992a) Bark beetle attack on host logs reduced by spraying with repellents. J. Appl. Ent. 114, 83-90. 

Effects of pheromone dose on trap catch have been studied. The usual amount of pheromone per septum was 500 pg. In California, all doses of Ca. hemipterus pheromone from 15 to 15 000 pg per septum were significantly active in the field, and for Ca. mutilatus, all doses from 50 to 15 000 pg were active (Bartelt et al., 1994a). Attractiveness increased with pheromone dose throughout the range for both species. Similar trends were noted for these species in Australia when 500 - and 5000 -pg doses were compared (James et al., 1994). With Carpophilus beetles, high pheromone doses never became repellent. 

Dawkins didn t give us any details of how the bombardier beetle s defensive system might have evolved. To point out the problem with his argument, however, let s use what we know of the beetle s anatomy to build the best possible case for the evolution of the bombardier bee-tie. First, we should note that the function ofthe bombardier beetle s defensive apparatus is to repel attackers. The components of the system are (1) hydrogen peroxide and hydroquinone, which are produced by the secretory lobes (2) the enzyme catalysts, which are made by the ectodermal glands (3) the collecting vesicle (4) the sphincter... 

Essential oils from laurel were evaluated for fumigant toxicity against all developmental stages of the confused flour beetle (Tribolium confusum). GC-MS analysis showed that 1,8-cineole was the major component of the essential oils. The vapours of laurel essential oil were toxic to all the stages of T. confusum (Isikber et al., 2006). Repellency and toxicity of essential oil from L. nobilis (Lauraceae) against the rust-red flour beetle T. castaneum Herbst) were also reported by Andronikashvili and Reichmuth (2003). The toxicity of ethanol extracts from L. nobilis on the large diamondback moth, Plutella xylos-tella, was 55% (Erturk et al., 2004). 

AndronikashviIi, M. and Reichmuth, C. (2003) Repellency and toxicity of essential oils from Ocimum gratissi-mum (Lamiaceae) and Laurus nobilis (Lauraceae) from Georgia against the rust-red flour beetle (Tribolium castaneum Herbst) (Coleoptera Tenebrionidae). Proceedings of 8th International Working Conference on Stored Product Protection, York, UK, 22-26 July 2002, pp. 749-762. 

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