Neuropeptides in the desert ant : Mass spectrometric analysis, localization, and age‐related changesCataglyphis fortis: Mass spectrometric analysis, localization, and age‐related changes
It has been shown that the transition between interior workers and foragers in insect societies is codetermined by external factors, such as variable numbers of brood, food, and foragers (Kolmes, 1985; Gordon, 1989; for review see Robinson, 1992; Mersch, 2016). Juvenile hormone (JH) levels, in concert with vitellogenin (Vg) and ecdysteroids, were shown to change with the interior–forager transition in honeybees (Jassim et al., 2000, Elekonich et al., 2001) and in ants (Dolezal et al., 2012). JH and its analogue methoprene were shown to influence the onset of the interior–forager transition and several aspects associated with it, such as the expression of genes related to the transition or biogenic amine levels (for review see Pandey and Bloch, 2015). However, it appears unlikely that JH alone orchestrates the species‐specific sequence of distinct changes in behavioral patterns at various stages of age‐related polyethism and the neuronal changes associated with the transitions. For example, it was shown that disturbance of the JH/Vg system did not affect neuroplasticity in the mushroom bodies (Scholl et al., 2014). Recent studies in the honeybee therefore have started to focus on neuropeptides, in particular their potential roles in orchestrating behavioral plasticity in social insects (Brockmann et al., 2009; Pratavieira et al., 2014). Candidates suggested by these studies are neuropeptides of the allatostatin (Ast), short neuropeptide F (sNPF), and tachykinin (TK) families. In Hymenoptera genomes three functionally distinct Ast families, AstA, C, and CC, have been identified (Hummon et al., 2006; Hauser et al., 2010; Nygaard et al., 2011), but only AstA could be biochemically identified bona fide in bees and ants (Hummon et al., 2006; Boerjan et al., 2010; Schmitt et al., 2015). In ants and bees, all peptide families listed above were shown to be present in the brain, the main center for the integration and processing of sensory information and decision making (for reviews see Ritzmann and Büschges, 2007; Niven et al., 2008), suggesting their neuromodulatory roles in behavior (Zitnan et al., 1993; Boerjan et al., 2010; Schmitt et al., 2015).