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Genus Ovatus

Hawthorn - mint aphids

On this page: Genus Ovatus  Ovatus crataegarius  Ovatus inulae  Ovatus mentharius 

Genus Ovatus [Macrosiphini]

Ovatus are small to medium sized greenish aphids, the adult viviparae of which may be winged or wingless. Their antennae are curved and longer than the body with the terminal process more than 5 times longer than the base of antennal segment 6. Antennal tubercles are well developed with the inner faces convergent in dorsal view, and two additional bumps on the head. The siphunculi taper gradually from base to flange and are longer than the cauda. The winged forms have no black central abdominal patch.

There are about 10 palaearctic species of Ovatus, three of which host alternate between hawthorn and apple (Rosaceae: Pyroidea) and mints (Labiatae), while the others live all-year-round on the former secondary hosts. They are not attended by ants. One species is a pest of mint.

 

Ovatus crataegarius (Hawthorn - mint aphid)

The aptera of Ovatus crataegarius is yellow-green to apple-green, sometimes mottled with darker green markings. The antennae are curved, and about 1.2-1.5 times the length of the body. The inner faces of the antennal tubercles are apically convergent in dorsal view. The pale siphunculi are 1.7-2.6 times as long as the tongue-shaped cauda. The body length of adult apterae ranges from 1.5-2.0 mm.

Note: On their primary host, hawthorn, Ovatus crataegarius fundatrices and apterae are morphologically indistinguishable from Ovatus insitus, a sibling species that host alternates from hawthorn to gipsywort (Lycopus europaeus). However, the spring migrant winged forms can be differentiated (see below).

The alate has a green abdomen with darker green patches. The spring migrant winged forms of Ovatus crataegarius have 22-49 secondary rhinaria on antennal segment III and 5-20 on antennal segment IV (cf. Ovatus insitus which have 60-83 secondary rhinaria on antennal segment III, and 36-52 on antennal segment IV). The oviparae of Ovatus crataegarius also have fewer pseudosensoria on their hind tibiae than those of Ovatus insitus.

The primary host of the hawthorn - mint aphid is hawthorn (Crataegus) and, less commonly, apple (Malus) or quince (Cydonia). In summer it host alternates to mint (Mentha) where it can reach pest status. In warmer climates Ovatus crataegarius may occur as an anholocyclic form on mint, overwintering viviparously near the ground. Ovatus crataegarius has a near worldwide distribution from Europe and the Middle East to Central Asia, India, Pakistan, parts of Africa, the USA, Canada and Brazil.

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Ovatus inulae (Fleabane aphid)

Adult apterae of Ovatus inulae range from lemon-yellow to pale green in colour. The fused last two segments of the rostrum (RIV+V) are 2.2 - 2.4 times longer than the second segment of the hind tarsus and bears 15-25 small accessory hairs (cf. all other Ovatus  species which have a shorter RIV+V with only 2-6 accessory hairs). The head has a well-developed median frontal tubercle, as well as rounded forwardly directed processes on the antennal tubercles, all clearly visible in the first picture below. The body length of adult apterae is 1.0-1.6 mm.

The Ovatus inulae alate (see second picture above) has a pale greeny-yellow abdomen and a brown thorax. Like the aptera, the apical rostral segment (RIV+V) is unusually long - more than 2.2 times longer than the second segment of the hind tarsus (HTII).

Ovatus inulae lives all year round on fleabane (Pulicaria dysenterica). It feeds on the undersides of the leaves and shoot apices, and especially the bases of the flowers. It can also be found on certain Inula and some other Asteraceae species. Sexual forms are produced in the autumn. The species is found throughout Europe into central Asia.

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Ovatus mentharius (Mint aphid)

Ovatus mentharius apterae have been described as greenish-white (see first picture below), but pale green with darker green markings may be a better description of the adult aptera. The antennae are as long as, or longer than, the body. The inner sides of the antennal tubercle and the first antennal segment of Ovatus mentharius each have a forwardly directed process. The process on the antennal tubercle is as long as or longer than its basal width in dorsal view. The siphunculi are attenuated and cylindrical on the distal half, and at midlength are about as thick as the hind tibiae at midlength; the siphunculi are 2.0-2.5 times as long as the cauda. The body length of adult apterae of Ovatus mentharius is 1.2-1.8 mm.

The alate viviparous female has the head and thorax brownish, the abdomen green, the antennae black and the siphunculi brownish with paler bases. Immatures (see second picture above) are pale yellow-green.

The mint aphid does not host alternate and lives all year on the underside of leaves of mint (Mentha spp.). It is not attended by ants. Winged males and oviparae can be found in autumn. Ovatus mentharius is found over most of Europe south to Turkey and in central Asia.

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Acknowledgements

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

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