Cluster c7 could be observed from both views, in the same location observed in medium workers (Figure 3, H) but this cluster was always observed as two groups of four cells each, similar in size and shape (Figure 3, H, K). both a constant and a differential pattern of sNPFR clusters, with a higher number of sNPFR cells found in minor than in major workers. Those sNPFR cells detected Lycopodine in all worker subcastes appear to be involved in olfaction or SEG functions. The differential expression of clusters in subcastes suggests that sNPFR signaling is involved in regulating behaviors associated with specific subcastes and thus, division of labor. Some sNPFR cells appear to be involved in nutrient sensing and/or brood care, feeding behavior and locomotion. In colonies without brood, workers showed a lower cluster number, and an overall reduced sNPFR signal. Our results suggest the sNPF signaling system is a candidate for the neurobiological control of worker division of labor and sensing brood presence, perhaps correlating with protein requirements and availability. == Introduction == The red imported fire ants (Solenopsis invictaBuren; Hymenoptera: Formicidae) are eusocial insects native from South America with an extraordinary capacity for adaptation to different environments. They have invaded countries such as the United States, Australia, New Zealand, China and Taiwan[1]. They are considered a dangerous invasive species in the U.S., affecting the habitat of other native animals[2][4]. Fire ant colonies are composed by individuals from different castes, designated as the reproductives (males and females) and the workers. This reproductive division of labor refers to specialization of drones and queens for the generation of new individuals, while female worker ants co-operate and perform brood rearing, care for the queen, forage for food, defend the nest, dig soil for nest construction, etc. The worker caste is composed of a greater number of individuals compared to the reproductive caste, Rabbit polyclonal to CIDEB and its members present large variations in body size. This size variation is known as worker polymorphism and in fire ants is the basis for the division of the worker caste into three loosely defined subcastes, as follows. Minor ants are the smallest workers, while major ants are the biggest. Lycopodine The third subcaste corresponds to medium workers of intermediate size between the former[5]. Previous studies showed that there is a correlation between the worker body size and the labor they perform, and it is believed this specialization of workers is necessary to increase their efficiency. However, other factors such as worker age influence task performed, making the prediction of worker task based on size less accurate. In the fire ants there are two main categories of workers, nurses and foragers, each group composed by a wide age/size range of ants. A third category of workers called reserves is very heterogeneous in age, size and behavior; they may work as nurses or foragers, or they may store liquid food, to which the name reserves refers to. In general, the smallest and youngest ants are responsible of taking care of Lycopodine the brood while older ants prefer to forage. However, foragers never feed larvae and nurses never forage[6]. In other ants and bees the endocrine mechanism appears to be related to a higher juvenile hormone titer in older workers that promotes foraging in comparison to younger nurses that remain in the nest[7]. Importantly, fire ant female workers are completely sterile, without ovaries, and thus are devoid of reproductive plasticity. Only queens can produce eggs. This makes this species a good model to separate female gene networks related to reproduction (queens) from those related to female worker tasks. Previous studies in other ant species have shown that the worker division of labor and the differences workers have when compared with the reproductive Lycopodine castes (drones, queens) are correlated with differences in the structure and organization of their brains[8][11]. For example, workers of several species of ants Lycopodine generally present small optic lobes and large antennal (olfactory) lobes compared with males and queens; and this correlates with the size of the mushroom bodies, especially in the latter input regions (lip and collar)[12],[13]. In carpenter ants,Camponotus.
Cluster c7 could be observed from both views, in the same location observed in medium workers (Figure 3, H) but this cluster was always observed as two groups of four cells each, similar in size and shape (Figure 3, H, K)