We used the cobalt-backfilling method to map the somata of neurones with axons that project in the two paired lateral nerves of the abdominal neuromeres of the locust Schistocerca gregaria with the objective of expanding and bringing together the incomplete and scattered information on these efferent neurones. We compared somata sizes and positions, and the pathways of primary neurites, with information from previous studies on individual, or groups of, abdominal neurones and we identify many of the somata we mapped. The stained somata belong to paired motor neurones and paired neurosecretory neurones, to unpaired neuromodulatory neurones (dorsal unpaired median, DUM, neurones) and unpaired bilaterally projecting neurones. In different neuromeres, the total number of somata with axons in these lateral nerves ranges from 73 to 106. Within an individual segmental neuromere, approximately 25 % of the somata belong to neurones with axons in nerve 1 (N1) and 35 % to those with axons in nerve 2 (N2) of that segment, while the remaining 40 % belong to neurones with axons in N1 of the next posterior segment. This basic pattern is repeated in all abdominal neuromeres, with differences in the percentages depending on whether the neuromeres are pregenital fused, pregenital unfused or genital. Nerve 1 contains the axons of 26–37 neurones with central somata in different neuromeres, of which 40 % are in the segmental neuromere and 60 % in the next anterior neuromere. In the segmental neuromere, 15 % of somata are ipsilateral to the nerve, 30 % are at the midline and 55 % are contralateral, whereas in the next anterior neuromere, 70 % are ipsilateral, 10 % are at the midline and 20 % are contralateral. Nerve 2 contains the axons of 11–28 neurones in different neuromeres, all of which have somata in the same segmental neuromere from which the nerve projects. Of these, approximately 70 % are ipsilateral, 30 % at the midline and none contralateral, except for the first abdominal and eighth male abdominal neuromeres, where one and two somata, respectively, are contralateral.
In the field: an interview with Harald Wolf
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In our new Conversation, Harald Wolf talks about his fieldwork experiences working with desert ants in Tunisia to understand their navigation.
Propose a new Workshop
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Our Workshops bring together leading experts and early-career researchers from a range of scientific backgrounds. Applications are now open to propose Workshops for 2024, one of which will be held in a Global South country.
Julian Dow steps down and John Terblanche joins the JEB team
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After 15 years with the journal, Julian Dow from University of Glasgow, UK, is stepping down as a Monitoring Editor. We wish Julian all the best for the future and welcome John Terblanche, Stellenbosch University, South Africa, who is joining the team. Julian talks about his long association with The Company of Biologists and the journal and John tells us about his life and career in this News article.
The capture of crude oil droplets by filter feeders at high and low Reynolds numbers
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Researchers from the University of Montreal, Canada, reveal how tiny filter feeding barnacles and Daphnia entrap and consume minute droplets of crude oil, introducing the pollutant at the bottom of the food chain.
Patterns and processes in amphibious fish
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In their Review, Keegan Lutek, Cassandra Donatelli and Emily Standen discuss the biomechanics and neural control of terrestrial locomotion in amphibious fish. They explore how locomotor mode depends on body shape, physical constraints and phylogeny.
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