Solenopsis ants

Examination of the venom content of the workers of Solenopsis maboya revealed the presence of (5Z,9Z)-3-butyl-5-methylindolizidine (107), (5E,9E)-3-butyl-5-methylindolizidine (108) and frans-2-methyl-6-nonylpiperidine (109), while analysis of the extract of the queens revealed the presence of a single alkaloid, ris-2-heptyl-5-methylpiperidine (110) (Fig. 19) [117]. Such caste-specific alkaloidic contents has been already been found in other Solenopsis ants [ 118,119] and suggest different roles for these compounds in each caste. 

One of the earliest reports published on insect chemical mimicry (Vander Meer and Wojcik, 1982) involved Myrmecaphodius excavaticolli beetles (Coleoptera) and Solenopsis ants. Both are imported species, almost certainly introduced into North America at the same time. The authors stated that the myrmecophagous beetle acquired the chemicals used for... 

Solenopsis ants produce piperidine alkaloids which resemble the plant alkaloid coniine. These alkaloids are strong deterrents and inhibit several cellular processes, such as electron transport chains (Table IV) 28,494). Many insects indicate the content of toxic natural products by warning colors (aposematism) or by the production of malodorous pyrazines 4,17,231,494). 

Figure 27 Piperidine and Indolizidine alkaloids from Solenopsis ants.

Some ants make products reminiscent of the coccinellid alkaloids. Three indolizidines are known from the venom gland of Monomorium pharaonis (Figure 9.10), and a pyrrolizidine from a Solenopsis ant has been known for some time. They would appear to be formed from polyketides or fatty acids as in the case of the coccinellines. More pyr-rolizidines and indolizidines with two alkyl and alkenyl groups have been found in Monomorium and Solenopsis species. Tetraponerine ants smear the venom of their poison glands onto prey. The venom consists of tricyclic alkaloids called tetraponerines (Figure 9.10). They are divided... 

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]. 

Glancey BM (1986) The queen recognition pheromone of Solenopsis invicta. In Lofgren CS, Vander Meer RK (eds) Fire ants and leaf-cutting ants biology and management. Westview Press, Boulder, p 223... 

Phillips, S.A., Jr. D.M. Clabom, and O.F. Francke. 1984. Comparison of aerial application and single-mound drenches of fenvalerate against the red imported fire ant, Solenopsis invicta Buren, in Texas. Southwestern Entomol. 9 164-168. 

Mirex (dodecachlorooctahydro-l,3,4-metheno-2H-cyclobuta [tv/] pentalene) has been used extensively in pesticidal formulations to control the red imported fire ant (Solenopsis invicta), and as a flame retardant in electronic components, plastics, and fabrics. One environmental consequence of mirex was the severe damage recorded to fish and wildlife in nine southeastern states and the Great Lakes, especially Lake Ontario. In 1978, the U.S. Environmental Protection Agency banned all further use of mirex, partly because of the hazards it imposed on nontarget biota. These included ... 

Sodium molybdate and other molybdenum compounds in toxic baits have potential for termite control (Brill et al. 1987). Baits containing 1000 mg Mo/kg were fatal to 99% of the termite Reticu-litermes flavipes in 48 days. After 8 to 10 days, termites became steel-gray in color, but appeared otherwise normal. Mortality began only after day 16. Termites did not avoid the poisoned bait, even at concentrations of 5000 mg Mo/kg. Yoshimura et al. (1987) reported similar results with another species of termite sodium molybdate killed 100% of the workers in a colony of Copotermes formo-sanus within 24 h after eating filter paper treated with a 5% solution. Some other species of insects — including fire ants (Solenopsis sp.) and various species of beetles and cockroaches — were not affected when exposed to baits containing 5000 mg Mo/kg for 48 days (Brill et al. 1987). 

Besides piperidine alkaloids, a total of 19 pyrrolidines have been found in the secretions of thief ants and fire ants of the genera Solenopsis and Monomorium. Among these, compounds 80-84 are simple pyrrolidines with two saturated linear all-carbon side chains only in Solenopsis latinode is there a secondary amine (82) and its methylated analog (85). One or two terminal unsaturations are present in compounds 86-91, which all possess a (hex-l-en)-6-yl chain and a 5-, 7-, or 9-carbon saturated chain. Compounds 93, 94, 96, 97, and 98 are the A-l-pyrrolines corresponding to pyrrolidines 80, 82, 90 (93 and 96 corresponding to 80, 94 to 82, and 97 and 98 to 90). 

It had been already reported, that the venom of the fire ant Solenopsis invicta is composed of 2-methyl-6-alkyl- or 2-methyl-6-alkenylpiperidines,the carbon chain of which has an odd number of carbon atoms in the range of 11 to 17 [ 115, 116]. Recently, Deslippe and Guo [120] reported that in workers of S. invicta from Texas the relative abundance of each alkaloid was highly correlated with worker size as well as with the ratios of saturated to unsaturated alkaloids. Moreover, young and old workers produced less venom than ants of intermediate age... 

In an effort to identify possible sources of the 16 alkaloids found in the skin of the Panamanian poison frog Dendrobates auratus, ants from a total of 61 terrestrial nests were analyzed [124]. The alate queens of one species of myr-micine ants (Solenopsis (Diplorhoptrum) sp.) collected at Cerro Ancon were found to contain the decahydroquinoline (-)-ds-195A (112) which was also present as a minor alkaloid in the skin of the microsympatric population of D. auratus. Moreover, from wingless ants of two nests collected at Isla Taboga and identified as Megalomyrmex silvestrU the same workers isolated the stereo-isomeric 3,5-disubstituted pyrrolizidines rfs-251 K (117) and trans-251 K (118) in the same ratio 3 1 that was present in the skin of a microsympatric population of D. auratus (Fig. 20) [124]. 

Laboratory studies have indicated that ozone at l%Mg/m (0.10 ppm) was lethal to adult houseflies Musca domestica L.) and caused them to lay fewer eggs. Two cockroach species Paraplaneta americana L. and Nauphoeta cinerea Oliver) and the red fire ant Solenopsis invicta Buren) were exposed to ozone at SSSug/m (0.30 ppm) for up to 10 days. There was no unusual mortality or evidence of direct injury to individual insects. The fire ant workers were stimulated to migrate inside their nest initially, but further observations indicated no disruption of social behavior. These reports do not suggest that free-ranging insects would be directly affected by ambient concentrations of ozone in natural ecosystems or agroecosystems. 

Thirdly let ns consider ants. They are a social gronp and may forage across snbstantial distances as a group. Ants lay down a molecnlar trail for other ants to follow. The molecnles involved are termed trail pheromones. Now there are many species of ants and they nse different trail pheromones for the obvions reason of being able to follow the right trail as opposed to that of some other species. That for the hre ant, Solenopsis invicta, is a hydrocarbon of moderate complexity ... 

Two examples of the remarkable potency of avermectin Bj are its LD9Q of 0.02 to 0.03 ppm against the two-spotted spider mite, Tetranychus urticae, when applied to bean plants as a foliar spray and its control of the red imported fire ant, Solenopsis invicta, when applied as a bait at a level as low as 25 to 50 mg per acre (19). 

Venoms from the fire ants Solenopsis invicta and 5. geminata are free of detectable histamine but possess histamine-release activity. This activity can account for the edema, itch, redness, warmth, and possibly the pain and burning sensations resulting from fire ant stings. And it can be attributed to the piperidines which constitute the major component of the venom. It has actually been proved that 6-methyl-2-n-undecylpiperidines (Ic and Id), components of S. geminata, possess the histamine-release activity (75). Due to some of the above-mentioned various activities the piperidine alkaloids play roles as defensive compounds. In addition to 2-alkyl-6-methylpiperidines, their N-methyl derivatives (3) are found in S. pergandei, S. carolinensis, and S. conjurata, and 1-piperideine derivatives (6 and 7) in S. sp. A (Puerto Rico) and S. xyloni (Table I). 

Workers of pharaoh s ant, Monomorium pharaonis, utilize their poison gland secretion as an effective repellent in the same way as that of thief ants, Solenopsis (Diplorhoptrum) species, in order to steal brood from the nests of other... 

Solenopsis (Diplorhoptrum) conjurata and some other thief ants contain indo-lizidines and/or piperidines (Tables I and II). (5Z,8 )-3-Heptyl-5-methylpyr-rolizidine (48) has also been shown to be contained in the thief ant Solenopsis xenovenenum (Table IV). The poison glands of Aphaenogaster fulva and A. tennesseensis contain the tobacco alkaloid anabaseine (8), which functions as an attractant in A. fulva (Table I) (26). 

Stractures of 3-alkyl-5-methylindolizidines, found in thief ants, Solenopsis species (Table II), arrived at by gas chromatographic and mass spectral analysis were confirmed by coinjection and direct comparison with the synthetic sample. Indolizidine 15a from S. conjurata exhibits characteristic peaks at miz 152 (M — CHj) and 138 (M — C2H5, a base peak) as well as a parent peak at m/z 167 in the mass spectram. It corresponds to an isomer of 3-ethyl-5-methylindolizidine (15) which was prepared as a mixture of four stereoisomers by reductive amination of triketone 391 with ammonium acetate-sodium cyanoborohydride and sodium borohydride (Scheme 47). 

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