Worker pheromones

The role of the nervous system in pheromone biosynthesis in moths is not clearly understood. Christensen and co-workers [208-211] proposed that the neurotransmitter octopamine may be involved as an intermediate messenger during the stimulation of sex pheromone production in H. virescens. These workers suggested that octopamine was involved in the regulation of pheromone production and that PBAN s role lies in the stimulation of octopamine release at nerve endings. However, contradicting results concerning octopa-mine-stimulated pheromone production were reported in the same species as well as other moth species [163,172,212-214]. 

Apis mellifera Q-MG Delays worker foraging ontogeny reduces tbeir hemolymph JH titre (2E)-9-Oxodec-2-enoic acid 52, (2 E)-9-hydroxydec-2-enoic acid (71% (R)-(-)) 53, methyl 4-hydroxybenzoate 54, 4-hydroxy-3-methoxyphenylethanol 55 (collectively called queen mandibular pheromone QMP ) [138]... 

Larva Inhibits worker ovarian development Ten component blend of brood pheromone methyl ethyl palmitate 78 79, stearate 80 81, oleate 56 90,linoleate 82 83, linolenate 84 84a, specifically ethyl palmitate methyl linolenate [121,122]... 

Larva Decreases worker response proboscis threshold to sucrose in a extension response increases number of pollen foragers Ten component blend of brood pheromone [123]... 

The queen is usually reproductively dominant within the colony and uses chemical cues as both primer and releaser pheromones to suppress the production or fecundity of other sexuals, inhibit reproduction by worker castes, modulate reproductive behaviors (e.g., inhibit swarming and orient swarms), attract males, regulate worker tasks and worker ontogeny, and produce host repellents in slave-making species. Considering the importance of queen semiochemicals in social hymenoptera, few queen pheromones have been chemically identified. The queens of most social hymenopteran colonies are attractive to workers, allowing them to be properly tended as well as to facilitate the dissemination of other pheromone cues. However, the retinue pheromone has been chemically identified in very few species. In the 1980s, queen pheromone components were identified in the fire ant, Solenopsis invicta [91,92], and in the Pharaoh s ant, Monomoriumpharaonis [93]. 

Although many queen-produced pheromones are actively being studied in ants, particularly in the fire ant (Solenopsis invicta) [10,105-110], chemical identifications remain elusive. However, there have been a few recent advances in ants. The queen of the slave-making species Polyergus rufescens produces de-cyl butanoate 60 that repels host workers when upsurping a colony [111]. Males of Formica lugubris are attracted to alate queens by undecane 61, tridecane 62 and (4Z)-tridec-4-ene 63 [112]. 

Within Hymenoptera, pheromones produced by workers in social colonies are the best studied across many genera, principally in ants [6], with those eliciting trail following most extensively studied. The distinct behavior and the relative ease of the bioassay have resulted in chemical identifications in many species [ 113,114]. Those that have been recently identified are listed in Table 5. In addition, several alarm and recruitment signals have recently been identified. Many of the compounds recently identified in ants have previously been reported as trail or alarm pheromones in other ant species. For example, methyl 4-methylpyrrole-2-carboxylate 64, 3-ethyl-2,5-dimethylpyrazine 65, (9Z)-hexadec-9-enal 66,4-methylheptan-3-ol 67, and methyl 6-methylsalicy-late 68 have been identified as trail pheromone components, and heptan-2-one 69,4-methylheptan-3-one 70, formic acid 71, undecane 61,4-methylheptan-3-ol 67, methyl 6-methylsalicylate 68, and citronellal 72 have been identified as alarm pheromone components [6]. The use of the same chemicals across genera, with some used for very different functions, is an interesting phenomenon. 

The female produced sex pheromone of Aleochara curtula has been described to consist of a mixture of (Z)-7-henicosene and (Z)-7-tricosene [114]. The same compounds are reported to be used by young males as a kind of camouflage to avoid aggression from older males. Similarly, chemical camouflage by using hydrocarbons plays a role in the relations between the myrme-cophilous staphylinid beetle Zyras cones and the ant Lasius fuliginosus. The host worker ants never attack these beetles which show the same profiles of cuticular hydrocarbons as the ants [115]. 

The biosyntheses of the sap beetle pheromones has been carefully investigated by Bartelt and his co-workers [47,48]. The typical methyl-branching of the compounds originates from propanoate (or methylmalonate) units that form the principal structures (see Fig. 2). Replacement of propanoate by butyrate during chain elongation yields ethyl-branching. In about half of the compounds (125-128,133-136,138-140, and 144) the structures suggest acetate to act as a starter while in 133 and 147 the starter should be butyrate. The chains... 

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