Reproductive development and ontogeny of queen pheromone production in the fire ant Solenopsis invicta

Abstract

Queens of the fire ant, Solenopsis invicta Buren, produce several releaser and primer pheromones. Using bioassays, the ontogeny of three of these pheromones related to reproductive development was investigated. Virgin queens, in which the process of wing‐shedding (dealation) serves as an indicator of the initiation of reproductive development, were studied. First, the production of two queen pheromones produced in the poison gland was examined. The pheromone responsible for initiation and maintenance of retinue formation, a releaser effect, was found to be produced in detectable quantities 2 days after dealation, at which time queens showed significant ovary development and many (30%) had started laying eggs. A primer pheromone that inhibits alate virgin queens from dealating was detected in queens 3 days following wing‐shedding, when 80% of the queens were ovipositing. Second, I examined the onset of a pheromone of unknown glandular origin produced by reproductively active virgin queens which leads to their destruction in queenright colonies by stimulating workers to attack and kill them. This pheromone is secreted in quantities detectable by bioassay 2 days after dealation. Thus, in S. invicta, the ontogeny of three distinct queen pheromones is tightly linked with ovary development and initiation of egg laying. These results demonstrate reproductive and communicative functions are closely associated during the transition from potential to functional queen.

A queen pheromone induces workers to kill sexual larvae in colonies of the red imported fire ant ( Solenopsis invicta )

“…Unlike our finding for S. invicta, however, unfertilized queens of the latter two species do not become influential following the shedding of wings (Edwards 1987;Passera et al 1995). Dealation corresponds to rapid changes in the endocrine system of S. invicta queens, and these changes stimulate ovary development and the production of several pheromones (Vargo 1998(Vargo , 1999, including the pheromone inducing workers to kill sexual larvae (this study). When alate queens are removed from the presence of dealated queens, they escape the influence of an inhibitory pheromone and shed their wings even though they remain unfertilized Blum 1981, 1983).…”

Comparisons of the queen volatile compounds of instrumentally inseminated versus naturally mated honey bee (Apis mellifera) queens

“…Differences in pheromone production between virgin and mated queens has also been shown for other honey bee subspecies such as Apis mellifera carnica (Engels et al, 1997) and A. m. capensis (Wossler et al, 2006) as well as in some ant species such as Solenopsis invicta (Vargo, 1997(Vargo, , 1999 and Myrmica rubra (Brian, 1973). Compounds found in high relative amounts only in virgin queens less than 48 hrs old might be important during the honey bee queen reduction process.…”

Queen-queen competition and reproductive skew in a Cardiocondyla ant

“…Queen aggression and / or queen pheromones apparently impede the shedding of wings by virgin female sexuals. Older queens might in this way prevent virgin sexuals from laying unfertilized eggs, as documented in Solenopsis invicta (e.g., Willer and Fletcher, 1986;Vargo, 1999).…”