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Pale green tansy aphidOn this page: Identification & Distribution Biology & Ecology Natural enemies Other aphids on the same host Damage & Control
Identification & Distribution
Adult apterae of Macrosiphoniella persequens are green with a darker green spinal stripe and bright red eyes. The antennae are light brown, but with dark apices to the segments (cf. Macrosiphoniella tanacetaria and Macrosiphoniella millefolii, which have mainly black antennae). The apparent light brown shading around and between the siphunculi probably results from subcuticular fat bodies. The apical rostral segment (RIV+V) is only 0.7-0.8 times the length of the second hind tarsal segment (HTII) (cf Macrosiphoniella sejuncta in which RIV+V is 1.1-1.3 times as long as HTII). The body hairs are not placed on dark scleroites. The legs are green-brown, with the distal ends of the tibiae and the tarsi black. The siphunculi are pale with dark tips, have reticulation over the distal 32-42% of length, and are 1.1-2.0 times the length of the cauda. The cauda has 24-30 hairs. The body length of the adult Macrosiphoniella persequens aptera is 4.2-5.2 mm.
The alate Macrosiphoniella persequens is very like the aptera, with no abdominal markings and with very thin siphunculi. Antennal segment III bears 50-59 secondary rhinaria spread along the whole segment. The ovipara has somewhat thickened hind tibiae, and the apterous male is small and dark green or pink.
Macrosiphoniella persequens feeds on the undersides of the lower leaves of tansy (Tancetum vulgare) (albeit we found it as an accidental on mugwort, Artemisia vulgaria - see below). Macrosiphoniella persequens has also been recorded from Pyrethrum millefoliatum. It does not host alternate. Sexual forms occur in autumn, and eggs are deposited on fallen foliage and mosses between plants. Macrosiphoniella persequens is found over most of Europe - but not Portugal, Norway, Italy, or the Baltic republics.
Biology & Ecology
The adult Macrosiphoniella persequens pictured above was found not on its normal host (Tanacetum vulgare), but on a nearby mugwort plant (Artemisia vulgaris) which is not known to host this species. The likely reason for this soon became apparent when we found mummies (see image below), apparently of this species, on the tansy: It is well known that parasitised aphids often leave the aphid colony before mummification. It has been suggested that this behaviour is an example of host manipulation by the parasitoid to reduce the risk of hyperparasitism after mummy formation. Müller et al. (1997) tested this hypothesis by surveying mummification site and hyperparasitism risk in 16 species of aphid. It turned out that mummification away from the colony was not associated with reduced hyperparasitism. Moreover for ant-attended species and in species with well-developed parasitoid defense behaviour such as kicking, mummies formed within the colony tended to suffer less hyperparasitism. An alternative explanation for the behaviour is that leaving the colony is simply a consequence of the trauma of parasitism in the same way that some aphid species tend to leave the colony for moulting.
The only parasitoid so far recorded from Macrosiphoniella persequens is Aphidius absinthi (Rakhshani et al., 2011). The appearance of mummies of this species that we found (see picture below) is very similar to those of Macrosiphoniella absinthi that we suspected had also been parasitized by Aphidius absinthi.
The mummified aphid in the picture below appeared to be under attack by a predatory larva, a possible example of intraguild predation (see Prieto et al., 2018).
Other aphids on the same host
Macrosiphoniella persequens has been recorded from 2 Tanacetum species: Tanacetum vulgare and Tanacetum millefolium (= Pyrethrum millefoliatum).
Blackman & Eastop list 23 species of aphid as feeding on Tanacetum vulgare worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 17 as occurring in Britain (Show British list).