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Hymenoptera have haploid males, which produce sperm by cloning. Sperm selection theory predicts that because termites have diploid males that produce genetically diverse sperm, they may profit from a high sperm surplus (large K), whereas Hymenoptera (ants, bees and wasps) should produce few sperm per fertilization (low K). Male reproductive "kings", which continuously provide spermatozoa during the whole life of the queen, allow for a large K. Available empirical evidence confirms the existence of a large difference in K between diploid insects, especially Blattodea (Isoptera) (K > 1,000), and haplo-diploids such as Hymenoptera (K < 10). The available data suggest that sperm selection may be an important evolutionary force for species with diploid, but not haploid males.

Chemical analyses by GC-MS of the metapleural glands (MG) from workers of Solenopsis invicta and S. geminata revealed for the first time the chemical composition of these glands and showed small differences between the two species. The MG of both species contain oleic, stearic, linoleic, and palmitic acid. Both ants, in addition, have small but significant amounts of hydrocarbons in their MG reservoir, which are the same as those found in their postpharyngeal glands (PPG). The PPG of both species contain alkanes, alkenes, and Me-branched alkanes. Each species is characterized by a specific composition of PPG chemicals with some overlap between species. These results suggest that the MG synthesizes mainly palmitic, linoleic, oleic, and stearic acids in these two ants, whereas PPG contains hydrocarbon mixes that widely vary between these two phylogenetically related species.

Ants in the tribe Cephalotini are exceptional in that they maintain microorganisms in their digestive tract. To understand what these microorganisms mean to the ants, we observed the feeding habits of Cephalotes pusillus and Cephalotes atratus, finding that in nature they feed on extrafloral nectars, homopteran secretions, and bird droppings. Feeding the antibiotic kanamycin to colonies of C. pusillus in the laboratory kills them. Ants desiccate or starve rather than feed on liquids to which the antibiotics gentamycin and netilmycin have been added, but feed and survive on liquids containing nystatin, penicillin, and ampicillin. We identified over 10 microorganisms from the intestine of C. pusillus with different antibiotic-resistance patterns. The bacteria are from the genera Corynebacterium, Brevibacterium, Sphingobacterium, Ochrobactrum, Myroides, Brevundimonas, Alcaligenes, Stenotrophomonas, Moraxella, and Pseudomonas. We hypothesize that the microorganisms provide nutrients to the ants by synthesizing amino acids from carbohydrates and nitrates. We do not know whether the ants collect the bacteria from the environment, but they transmit them to their young. They culture them in their digestive tract, eventually feeding on them.Les fourmis de la tribu des Cephalotini sont remarquables en ce qu'elles gardent des microorganismes vivants dans leur tube digestif. Pour comprendre le rôle que jouent ces microorganismes chez les fourmis, nous avons observé les habitudes alimentaires de Cephalotes pusillus et de Cephalotes atratus et avons constaté qu'en nature, ces fourmis se nourrissent de nectars extrafloraux, de sécrétions d'homoptères et de fèces d'oiseaux. L'addition d'un antibiotique, la kanamicine, à des colonies de C. pusillus en laboratoire tue les fourmis. Les fourmis se dessèchent ou meurent de faim plutôt que d'ingérer des liquides additionnés des antibiotiques gentamicine ou nétromicine, mais il se nourrissent de liquides additionnés des antibiotiques nistatin, pénicilline et ampicilline. Nous avons identifié, dans le tube digestif de C. pusillus, plus de 10 microorganismes qui montrent des patterns de résistance différents selon l'antibiotique. Les bactéries appartiennent aux genres Corynebacterium, Brevibacterium, Sphingobacterium, Ochrobactrum, Myroides, Brevundimonas, Alcaligenes, Stenotrophomonas, Moraxella et Pseudomonas. Nous croyons que les microorganismes fournissent des matières nutritives aux fourmis en synthétisant des acides aminés à partir des hydrates de carbone et des nitrates. Nous ne savons pas si les fourmis récoltent les bactéries dans leur milieu, mais elles les transmettent à leur progéniture. Elles les élèvent dans leur tube digestif et finissent par s'en nourrir.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]