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Genus Ovatus

Hawthorn - mint aphids

Species Overview: Genus Ovatus  Ovatus crataegarius  Ovatus crataegarius 

Genus Ovatus [Macrosiphini]

Small to medium sized greenish aphids, the adult viviparae of which may be winged or wingless. 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 hawthorn-mint aphid is a yellow-green to apple-green aphid, sometimes mottled with darker green markings. The antennae are curved about 1.2-1.5 times the length of the body. The pale siphunculi are 1.7-2.6 times as long as the tongue-shaped cauda. The body length of apterae ranges from 1.5-2.0 mm.

Fundatrices and apterae on hawthorn are morphologically indistinguishable from Ovatus insitus, a sibling species that host alternates from hawthorn to gipsywort (Lycopus europaeus). However the spring migrant winged forms of Ovatus insitus have more rhinaria (60-83) on the antennae than those Ovatus crataegarius (22-49). Their oviparae also have more pseudosensoria on their hind tibiae than those of Ovatus crataegarius (not easy to see in photos!).

The hawthorn - mint aphid host alternates from hawthorn and apple (Rosaceae) to mint (Mentha, Lamiaceae) where it can reach pest status. In warmer climates it may overwinter viviparously near the ground.

 

Ovatus mentharius (Mint aphid)

Ovatus mentharius apterae have been described as greenish-white but our photos (see first picture below) show that pale green with darker green markings may be a better description. Immatures (see second picture below) are pale green. The antennae are as long as the body or longer. The inner sides of the antennal tubercle and the first antennal segment 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; they are 2.0-2.5 times as long as the cauda. The body length 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.

The mint aphid does not host alternate and lives all year on the underside of leaves of mint (Mentha spp.). We have found flourishing colonies on water mint in March in UK. Winged males and oviparae can be found in autumn. Ovatus mentharius is not attended by ants.

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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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