Aphid soldier differentiation: Density acts on both embryos and newborn nymphs

Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 305-8566, Tsukuba, Japan.
The Science of Nature (Impact Factor: 2.1). 12/2003; 90(11):501-4. DOI: 10.1007/s00114-003-0474-8
Source: PubMed


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.

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    • "Very little is known about the molecular mechanisms by which aphid developmental paths diverge to produce different morphologies. Some aphid phenotypes are conditioned very early in the development of the aphid (Hardie & Lees, 1985; Shibao et al., 2003), perhaps during embryogenesis. Beyond gross morphological and behavioural differences, the aphid life-style, particularly that of apterous viviparae, requires that individuals adapt to a dynamic environment, which may include changes in host plant metabolism, photoperiod, temperature, population density and the presence of predators and parasites. "
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    • "This finding was consolidated by examination of soldier proportions in field-collected colonies at high population density. The timing of this density-induced defense investment has also been investigated (Shibao et al. 2003). High aphid density was found to have a prenatal influence on embryos still within the ovarioles of their mothers, which resulted in increased soldier production. "
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