Nymphister kronaueri, parassita foretico di Eciton

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Nymphister kronaueri, parassita foretico di Eciton

Messaggioda winny88 » 17/02/2017, 11:02

Lavoro pubblicato la settimana scorsa che descrive il Nymphister kronaueri sp.n., piccolo coleottero Histeridae mirmecofilo, parassita dell' Eciton mexicanum.

Già sono stati osservati molti organismi mirmecofili parassiti degli Eciton che partecipano alle migrazioni degli ospiti. Ma la strategia osservata per seguire le formiche durante le migrazioni da parte di questo coleotterino è nuova. Si trasforma in parassita foretico, si aggancia con le mandibole tra peziolo e postpeziolo delle operaie di medio sviluppo, ritrae le appendici e mima la forma del gastro delle operaie. Si traveste da gastro di formica insomma e si fa trasportare. Conclusa la migrazione, scende e riprende le sue normali attività.

Furbo il bacarozzo!

https://bmczool.biomedcentral.com/artic ... 016-0010-x


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Re: Nymphister kronaueri, parassita foretico di Eciton

Messaggioda Elena Regina » 17/02/2017, 20:25

Attualmente si conoscono 4 specie appartenenti al genere Nymphister (Coleoptera Histeridae Haeteriinae Nymphistrini), presumibilmente simili dal punto di vista ecoetologico. Sarebbe interessante sapere qualcosa a proposito delle larve di questi isteridi [11 sff, 33 tbb, 330 gg, 3,900 spp].

M.S. Caterino & A.K. Tishechkin, 2006: DNA identification and morphological description of the first confirmed larvae of Hetaeriinae (Coleoptera Histeridae). PDF
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The circumstances in which the larvae described here were collected shed a glimmer of light on their habits. When discussing coleopteran myrmecophily, virtually all authors have concentrated on behavioural and morphological adaptations of the adult beetles. The niche of the larvae has rarely received attention. Considering the highly mobile colonies of army ants, the predominant hetaeriine hosts in the Neotropics, we know that some adult Hetaeriinae can follow ant trails, may run along or ride on hosts in emigration columns and may fly to find colonies. Of these, larvae are capable only of riding or being carried. An association with the statary phase of the army ant colony would seem more likely. Indeed, Torgerson & Akre (1970) found the ovaries of Euxenister adults enlarged and apparently ready to oviposit near the end of the nomadic cycles of their respective hosts. Both samples that produced hetaeriine larvae for this study were collected in association with Eciton colonies, although in varied phases of the ant cycle. The larvae of Paratropinus indeed were collected in ‘refuse deposits’ of a statary phase Eciton burchelli bivouac. The ‘nr. Euxenister’ larva, however, was sifted from litter beneath a large, temporary bivouac of nomadic Eciton burchelli. A few hours later these ants had moved on. Whether the larva would have moved on too or been carried along, cannot be known. Finding Paratropinus larvae in association with a statary phase bivouac supports Akre’s (1968) idea that, in some Hetaeriinae, there might be considerable synchrony in host–guest life cycles. However, the contrasting data for MSC1 indicate that, as with known adult behaviour, there is significant variation in larval habits. The statary phase of Eciton colonies corresponds to their pupal phase and would represent the only time in the colony life cycle when limited mobility of the beetle larvae would not pose a problem. Furthermore, this is the period in the ant life cycle when accumulations of refuse occur. Eciton burchelli are noted for producing nutrient-rich refuse deposits. Given the brevity of this phase (less than 3 weeks), the general brevity of the histerid larval stage is notable. Histerids are unusual amongst beetles in passing rapidly through only 2 larval instars before pupating. This might represent an important preadaptation to myrmecophily, particularly to associations with army ants, and might help explain histerids’ prevalence and diversity in this unusual niche. Finally, although the trees presented here were not intended to provide great insight into hetaeriine phylogeny, we discuss some details. [...] This study advances our understanding of hetaeriine biology along several fronts. In addition to eventually identifying and describing larvae of Hetaeriinae for the first time, we have identified some potentially useful variation in larval characters to aid in resolving relationships within Hetaeriinae, as well as for their placement relative to other lineages of Histerinae. Although hetaeriine larvae may not be easy to collect, targeting statary bivouacs of Eciton throughout the Neotropics (particularly those that appear to be used repeatedly, accumulating large refuse deposits) is likely to produce additional specimens and taxa. We also highlight the potential of nucleotide sequences for associating unknown larvae, whereas in the past, most dead, unassociated larval collections have been considered dead ends.

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