Aphid soldier differentiation: density acts on both embryos and newborn nymphs
ABSTRACT The mechanism of caste differentiation in a social aphid Tuberaphis styraci, which has a sterile soldier caste in the 2nd instar, was investigated using an artificial diet rearing system. High aphid density induced soldier production. Combinatorial prenatal and postnatal density treatments revealed that (1) either prenatal high density or postnatal high density is sufficient for soldier induction; (2) thus, embryos in the maternal body and newborn 1st instar nymphs are both responsive to high density; (3) the combination of prenatal high density and postnatal high density enhances soldier differentiation in a synergistic manner; and (4) the final determination of soldier differentiation occurs postnatally, probably at a late 1st instar stage. This study first throws light on the developmental aspects of caste differentiation in a social aphid.
- SourceAvailable from: Dayalan Gopal Srinivasan[Show abstract] [Hide abstract]
ABSTRACT: Aphids display extraordinary developmental plasticity in response to environmental cues. These differential responses to environmental changes may be due in part to changes in gene expression patterns. To understand the molecular basis for aphid developmental plasticity, we attempted to identify the chromatin-remodelling machinery in the recently sequenced pea aphid genome. We find that the pea aphid possesses a complement of metazoan histone modifying enzymes with greater gene family diversity than that seen in a number of other arthropods. Several genes appear to have undergone recent duplication and divergence, potentially enabling greater combinatorial diversity among the chromatin-remodelling complexes. The abundant aphid chromatin modifying enzymes may facilitate the phenotypic plasticity necessary to maintain the complex life cycle of the aphid.Insect Molecular Biology 03/2010; 19 Suppl 2:201-14. DOI:10.1111/j.1365-2583.2009.00972.x · 2.98 Impact Factor
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ABSTRACT: Field-collected 229 colonies of a pempbigine social aphid Colophina arma, which has a soldier caste in the first instar, were examined for its population dynamics, reproductive schedule, and ecological factors related to soldier production. Colony size was small in July and became larger in August and on; this change probably reflects the flowering phenology of the host plant Clematis stans. Soldiers, which neither grow nor reproduce but are specialized for colony defense, were found throughout the seasons. Winged sexuparae, which migrate to Zelkova serrata and produce the sexual generation, appeared in late September. Midget first instar nymphs, which persist on C. stans for hibernation, were produced in October. Statistical analyses suggested that soldier proportion in colonies of C. arma might be related to the proportions of unwinged adults, colony size, and seasonal change. Sexuparae and midget nymphs were produced only in autumn, which reflects the overwintering roles of these morphs, and suggests that production of these morphs might be influenced by environmental factors related to the season, such as short photoperiod and low temperature.Applied Entomology and Zoology 05/2005; 40(2):239-245. DOI:10.1303/aez.2005.239 · 0.88 Impact Factor
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ABSTRACT: Tuberaphis styraci is a social aphid that produces 2nd instar soldiers with morphological, behavioral and reproductive division. High aphid density was shown to induce soldier production in T. styraci, although direct cue of soldier induction associated with high density has been unknown. In order to identify the proximate environmental cue underlying the density-dependent soldier production, a series of experiments was conducted using an artificial diet rearing technique. When adult aphids were reared with live normal nymphs, live soldiers, dead normal nymphs, shed skins, honeydew globules and excreted wax, only live normal nymphs effectively induced soldier production. In order to gain insights into the nature of soldier-inducing cue associated with normal aphids, we performed artificial diet experiments using partitioned and non-partitioned chambers, in which direct contact between aphids was either inhibited or allowed. Induction of soldiers was observed only when direct contact was allowed. Therefore, it was shown that the soldier-inducing cue is neither volatile in the air nor diffusible through the diet, but is transmitted between normal non-soldier aphids via direct contact. On the basis of these results, we suggest that the soldier-inducing cue might be physical stimulus combined with non-volatile surface chemicals whose properties differ between normal aphids and soldiers.Journal of Insect Physiology 02/2004; 50(2-3):143-7. DOI:10.1016/j.jinsphys.2003.10.006 · 2.50 Impact Factor