Revisiting the anatomy of the central nervous system of a hemimetabolous model insect species: the pea aphid Acyrthosiphon pisum

Abstract

Aphids show a marked phenotypic plasticity, producing asexual or sexual and winged or wingless morphs depending on environmental conditions and season. We describe here the general structure of the brain of various morphs of the pea aphid Acyrthosiphon pisum. This is the first detailed anatomical study of the central nervous system of an aphid by immunocytochemistry (synapsin, serotonin, and several neuropeptides), ethyl-gallate staining, confocal laser scanning microscopy, and three-dimensional reconstructions. The study has revealed well-developed optic lobes composed of lamina, medulla, and lobula complex. Ocelli are only present in males and winged parthenogenetic females. The central complex is well-defined, with a central body divided into two parts, a protocerebral bridge, and affiliated lateral accessory lobes. The mushroom bodies are ill-defined, lacking calyces, and only being visualized by using an antiserum against the neuropeptide orcokinin. The antennal lobes contain poorly delineated glomeruli but can be clearly visualized by performing antennal backfills. On the basis of our detailed description of the brain of winged and wingless parthenogenetic A. pisum females, an anatomical map is now available that should improve our knowledge of the way that these structures are involved in the regulation of phenotypic plasticity.

Variations on a Theme: Antennal Lobe Architecture across Coleoptera

“…in Dytiscidae [43,45] (also confirmed by own observations [Fig 4H, 4H' and 4H'']), Odonata [42,43,67], and Hemiptera [42,68,69,129]. The five ladybug species investigated in this work also show small AL with diffusely demarcated microglomeruli (Fig 4C–4G) and also completely lack calyces, while the peduncles and the Kenyon cells are still clearly identifiable (Fig 4I–4I‴).…”

Novel antennal lobe substructures revealed in the small hive beetle Aethina tumida

“…The described anatomy of the 5HT-ir neuron has been described for Coleoptera before and can also be found in Lepidoptera, Trichoptera, non-Schizophoran Diptera and Neuroptera (Dacks et al, 2006) and is very likely also true for aphids (Kollmann et al, 2011b). A side branch of the 5HT-ir neuron into the ipsilateral lateral protocerebrum as observed in many insects (including Coleoptera; Dacks et al, 2006) could not be found in A. tumida.…”

Identification of the prothoracicotropic hormone (Ptth) coding gene and localization of its site of expression in the pea aphid Acyrthosiphon pisum

“…For a detailed description of the pea aphid central nervous system, refer to Kollmann et al . (). [Colour figure can be viewed at http://wileyonlinelibrary.com]…”