| Insect semiochemicals have proven to be environmentally benign tools for pest monitoring and control. The identification of semiochemicals also allows for meaningful behavioural studies to take place. Research towards the isolation and identification of semiochemicals for three insect species is described in this thesis.; Egg-laying queens of the red imported fire ant, Solenopsis invicta Buren, secrete chemicals that inhibit alate (winged) queens in the colony from dealating (wing shedding). Bioassay-driven isolation of these chemicals from queen hexane extracts is dependent upon worker attraction to lures so that they may deliver the active components to alate queens. Evidence suggested that worker attractants were not present. For this reason research efforts were redirected toward the identification of the chemicals which egg-laying queens use to attract workers. Two chemicals previously reported to elicit this attraction, 6-(1-pentenyl)-2H-pyran-2-one and tetrahydro-3S,5 R-dimethyl-6-(1R-methylbutyl)-2H-pyran-2-one (invictolide), did not account for the complete attraction attributed to queen extracts for colonies tested. Evidence is presented which suggests that at least one more unidentified non-polar mated queen component is required to elicit complete attraction.; Female tarnished plant bugs (TPB), Lygus lineolaris Palisot de Beauvois, chemically attract males from distances of at least 10 m in field experiments. Chemicals in female abdominal extracts were attractive to males in a laboratory bioassay and had similar elution characteristics on LC and HPLC columns as triunsaturated octadecenoic acids. A mixture of triunsaturated octadecenoic acids, linolenic acid [(Z,Z,Z)-octadeca-9,12,15-trienoic acid], gamma linolenic acid [(Z,Z,Z)-octadeca-6,9,12-trienoic acid] and linolenelaidic acid [(E,E,E)-octadeca-9,12,15-trienoic acid], were attractive to both males and females in the bioassay after a methanolic solution of the mixture was allowed to stand open to air for a period of at least 48 hrs. Evidence is presented that suggests females may also contain chemicals that inhibit attraction of other females.; Washes of adult worker honey bees, Apis mellifera L., contain chemicals that, when placed in an airstream, cause varroa mites, Varroa destructor, to orient and walk away from the source. These chemicals were identified as nerolic acid (3,7-dimethyl-Z-octa-2,6-dienoic acid) and geraniol (3,7-dimethyl-E-octa-2,6-dien-1-ol), the two most abundant components of the seven component Nasonov blend. Nerolic acid and geraniol, in combination, elicited the same repellent effect as adult honey bee washes. |
