J. M. Brand

Fire ant venoms: Comparative analyses of alkaloidal components

Abstract The chemistry of the venom alkaloids of Solenopsis geminata, S. xyloni and the red and black forms of S. saevissima was investigated. All four forms have a venom composition characterized by the presence of various 2,6-disubstituted piperidines in amounts distinctive of the form. The alkaloids of the red and black forms mainly contain an alkenyl group in position 6 and a trans configuration of the substituents on the piperidine ring, while those of the two indigenous species of North American fire ants contain alkyl substituents which are both cis and trans on the ring. In addition, the venom of S. xyloni contains detectable amounts of 2-methyl-6- n -undecyl- Δ 1,2 -piperideine, a possible precursor of certain of these alkaloids.

Bark beetle pheromones: Production of verbenone by a mycangial fungus ofDendroctonus frontalis

A mycangial symbiotic fungus ofDendroctonus frontalis is capable of oxidizingtrans-verbenol to verbenone. Both of these compounds are known to be important behavioral chemicals for this species, and it is suggested that development of the fungus in the plant host may play a role in influencing the behavior of the beetle to a successfully colonized tree.

Bark-beetle pheromones

The two major yeasts isolated from the southern pine beetle,Dendroctonus frontalis Zimmerman, areHansenula holstii Wickerham andPichia pinus (Hoist) Phaff; a third yeast,P. bovis van Uden et do Carmo-Sousa, has been isolated far less frequently. The main volatile metabolites produced by these yeasts are isoamyl alcohol, isoamyl acetate, 2-phenylethanol, and 2-phenylethyl acetate.We have found that certain of these compounds, particularly the esters, can greatly, enhance the attractiveness of a mixture of frontalin:trans-verbenol: turpentine (1:1:12), at certain limiting concentrations, to walking beetles in a laboratory bioassay.

Alarm pheromones in the genus Manica derived from the mandibular gland

Abstract The alarm pheromones present in the mandibular glands of Manica mutica and M. bradleyi are dominated by a novel C 10 ketone, 4,6-dimethyl-4-octene-3-one (manicone). Two other new insect pheromones, 4-methyl-3-hexanone and 3-decanone, are also present. In addition, two characteristic myrmicine alarm pheromones, 3-octanone and 4-methyl-3-heptanone, have been identified as mandibular gland constituents. While manicone functions as a powerful releaser of alarm behaviour for Manica workers a much weaker response was obtained to the other identified 3-alkanones. The significance of the occurrence of 3-ketones in members of the genus Manica and species in other genera of the Myrmicinae is analysed in terms of the accepted phylogeny of this subfamily.

Caste-Specific Compounds in Male Carpenter Ants

Three caste-specific substances new to arthropod glandular secretions occur in the mandibular glands of male ants of five species in the genus Camponotus. These volatile compounds, which are not found in alate females or workers, have been identified as methyl 6-methyl salicylate, 2,4-dimethyl-2-hexenoic acid, and methyl anthranilate. The free acid has not been described previously.

Identification of mellein in the mandibular gland secretions of carpenter ants.

Abstract The mandibular gland secretions of males of the ants Camponotus herculeanus, C. ligniperda , and C. pennsylvanicus contain three major volatile substances. These compounds have been identified as 3,4-dihydro-8-hydroxy-3-methylisocoumarin (mellein or ochracin), methyl 6-methylsalicylate, and 10-methyldodecanoic acid. Mellein has not been isolated previously from animal sources.

Chrysomelidial in the defensive secretion of the leaf beetleGastrophysa cyanea Melsheimer

Larvae of the chrysomelid beetleGastrophysa cyanea produce a defensive secretion in their eversible thoracic and abdominal glands that is an effective repellent for small predators such as fire ants. This secretion is composed primarily of chrysomelidial, 2-(2-formyl-3-methyl-2-cyclopentenyl)propanal, and a compound tentatively identified as its enol lactone. Adaptations that optimize the effectiveness of the larval defensive exudate are discussed.

Biochemical evolution in fire ant venoms

Abstract The distribution of 2,6-dialkyl(and alkenyl-)piperidine alkaloids in the venom of fire ant workers of Solenopsis xyloni, S. geminata, S. richteri , and S. invicta has been compared with the occurrence of these compounds in the venom of alate queens of the same species. Whereas the venoms of workers of S. invicta and S. richteri contain piperidines with C 13 or C 15 side chains, the queens of these species produce venoms in which these compounds are essentially lacking. A comparison of the ratio of cis -2-methyl-6- n -undecylpiperidine to trans -2-methyl-6- n -undecylpiperidine in all of these venoms, together with the qualitative differences of other alkaloidal components, particularly in workers of S. richteri and S. invicta , has led to the proposal that the venoms of S. xyloni and S. geminata are similar to the ancestral type, whereas those of S. richteri and S. invicta are more highly evolved.

Insect Pheromones: A Critical Review of Recent Advances in Their Chemistry, Biology, and Application

The chemical basis of insect behavior is firmly established and forms an integral part of regulatory biology. The many and varied studies on this topic constitute part of an overall attempt to understand behavior at the molecular level. A better understanding of this subject will only come about by interdisciplinary collaboration between chemists and biologists.

Fire ant venoms: intraspecific and interspecific variation among castes and individuals.

Abstract The ratio of cis -2-methyl-6- n -undecylpiperidine ( cis C 11 ) to trans -2-methyl-6- n -undecylpiperidine ( trans C 11 ) in the venom of individual workers and soldiers of Solenopsis geminata and in individual alate queens of S. geminata, S. xyloni, S. invicta , and S. richteri was estimated. A considerable variation in this ratio was demonstrated between individuals of a particular caste within a species. In spite of considerable individual variation, the various species nevertheless exhibit a fair degree of control of the biosynthetic system for these 2,6-disubstituted piperidine alkaloids. Results obtained on one colony of S. geminata soldiers suggested that these individuals may have arisen from at least two fertile queens in the nest.