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Aphis intybiSmall chicory aphidOn this page: Identification & Distribution Biology & Ecology Establishment in North America Population dynamics Interspecific competition / association Ant attendance Natural enemies Other aphids on the same host Damage & ControlIdentification & DistributionAdult apterae of Aphis intybi are black and wax-powdered to a greater or lesser extent, giving them a matt grey-black appearance (see first two pictures below) (cf. adult Aphis craccivora, which have a shiny black carapace). The dorsal abdomen has dark markings which are usually fused between segments to form a central patch or shield (cf. Aphis fabae, which has some dark markings on the dorsal abdomen, but they are not fused between segments). The hairs on antennal segment III are 0.25-0.75 times the basal diameter of that segment (cf. Aphis fabae, which has hairs on antennal segment III 0.8-3.4 times the basal diameter of that segment). The apical rostral segment (RIV+V) is 1.1-1.5 times the length of the second hind tarsal segment (HTII) and usually 1.25-1.75 times the base of antennal segment VI (cf. Aphis craccivora, which has RIV+V 0.7-1.3 times HT II, and usually 0.8-1.2 times the base of antennal segment VI). The siphunculi and cauda are both black. The cauda bears 4-9 hairs (cf. Aphis fabae, which has 11-27 hairs on the cauda). The body length of adult Aphis intybi apterae is 1.2-2.3 mm.
Both images above by permission, copyright Claude Pilon, all rights reserved. Alatae have 2-9 secondary rhinaria on antennal segment III, and 0-1 on segment IV. Aphis intybi does not host alternate, but remains all year on its host plant, chicory (Cichorium spp.). It is found on the young growth of Cichorium intybus in spring, and later at stem bases in ant shelters. Records from other plants are most probably misidentifications. Aphis intybi overwinters as eggs. Sexuales are produced in the autumn, beginning with apterous males. The small chicory aphid is native to Europe and the Mediterranean region - and regarded as invasive in west and central Asia, east to Pakistan. In America Aphis intybi is now known to be invasive in Canada (these observations with specimens in the Canadian National Collection, Footit et al., 2006). It has also been intercepted at ports of entry to the USA (Stoetzel & Russell, 1991), and has been introduced to Argentina and Chile.
Biology & EcologyEstablishment in North AmericaAphis intybi is a specialist on Cichorium (chicory, endive, escarole). It was initially intercepted at USA ports of entry on cultivated Cichorium species imported from Italy. Aphis intybi was first recorded in the field in North America by Claude Pilon, in two locations around Montreal in Quebec, Canada. Its foodplant, Cichorium intybus is a weedy invasive that grows along roadsides and fallow fields in North America. Skvarla et al., 2017 have suggested that Aphis intybi may spread and become widely established within North America, and thus act as a biocontrol agent for the invasive Cichorium intybus. Endive is grown in limited commercial quantities in North America, so Aphis intybi is unlikely to pose a major economic risk. The images shown above are from the two locations in which the species was first discovered in 2010. Population dynamicsHodjat (1975) made field observations on population fluctuations of Pergandeida intybi (= Aphis intybi) and another aphid species Dactynotus cichoricola (= ? Uroleucon cichorii) infesting endives (Cichorium endivia) in Iran. Infestation of chicory plants was first observed early in May, and increased to its maximum level by the flowering-stage of the host in June. By that time about 60% of the plants were infested. Soon after seed formation in July, the infestation level rapidly declined. This decline was thought to be partly due to the abundance of natural enemies in July and August. Interspecific competition / associationBasky (2016) looked at the aphid species colonizing perennial Asteraceae host species alongside Hungarian motorways. Establishment of motorways starts with levelling of the ground for the road bed construction. Depending of the configuration of the terrain the removed soil layer can be not thicker than 15"20 cm. During this procedure the natural vegetation is destroyed, but the remaining root layer of the perennial plant species serves propagation purposes. In the case of Asteraceae plant species, out of 11 aphid colonized daisy species ten are perennial, including common chicory Cichorium intybus. Three species of aphids colonized the chicory: Uroleucon cichorii, Aphis intybi and Aphis fabae cirsiiacanthoidis. Uroleucon cichorii was the most frequently collected species (at 7 sampling places), colonizing the upper part of the stems of Cichorium intybus. Aphis intybi was the second most frequently collected species on Cichorium intybus (at 4 sampling places). Aphis intybi was found on young shoots, later at stem bases, and colonies were ant attended. Aphis fabae cirsiiacanthoidis was found on Cichorium intybus on one occasion, although it mainly colonized Cirsium arvense. Ant attendanceSinchuk et al. (1975) studied the trophobiotic relationship between various (?) invasive aphids and local indigenous ant species. Aphis intybi was visited on the stems of chicory by the ant Lasius niger. Attendance by ants was found to be facultative rather than obligatory. The colonies of Aphis intybi photographed by Claude Pilon (see picture below) were also attended by ants (see picture below), again on the stems rather than at the stem base in ant shelters.
Images above by permission, copyright Claude Pilon, all rights reserved. Natural enemiesLike many species of ant-attended aphids living in the herbaceous plant and shrub layer (e.g. the black foxglove aphid Aphis armata, black bean aphid Aphis fabae and the ivy aphid Aphis hederae), Aphis intybi may be attacked by parasitic mites. These are larval velvety mites (family Trombidiidae) which suck the haemolymph of aphids, only killing them when there are several feeding on the same aphid. Adult velvet mites predate a variety of soil organisms, but their larvae are parasitic on various arthropods. Three genera of velvet mites (Allothrombium, Podothrombium and Monothrombium) are aphid specialists. The picture below shows young Aphis intybi nymphs, one of which has an attached trombidiid mite.
Images above by permission, copyright Claude Pilon, all rights reserved. The impact of mites upon their aphid hosts is reviewed by Zhang (1998). The effect of larval trombidium mites on an individual aphid depends on the parasitic mite load and the age/size of the aphid. The larvae of Allothrombium pulvinum can kill an adult black bean aphid (Aphis fabae) in 3 days when the mite load is two or more. With only one mite, the reproductive rate of adult aphids is decreased and the development of nymphs is arrested. We give more about trombidiid mites in Mites parasitizing and predating aphids. Other aphids on the same hostAphis intybi has been recorded from perhaps 3 Cichorium species (Cichorium divaricatum (?), Cichorium endivia, Cichorium intybus) - and possibly Crepis vesicaria, Cynara cardunculus, Lactuca spp., Lapsana communis, Taraxacum officinale, Xeranthemum cylindraceum (as overflow hosts?).
Damage and controlAphis intybi is considered a minor pest of chicory in Libya (Singh, 2006).
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