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Green chrysanthemum aphid, Pale chrysanthemum aphidOn this page: Identification & Distribution Other aphids on the same host Damage & Control
Identification & Distribution
Coloradoa rufomaculata (see first two pictures below) are very small aphids found on cultivated chrysanthemum. Adult apterae have large bright red eyes and a green dorsum, marked with a few yellow and red spots of internal colour. The antennae are 0.5-0.7 times as long as body, with the terminal process 1.5-2.0 times as long as base of last antennal segment; antennal segments V & VI are dark brown. Antennal hairs are very short, about 0.25 times the basal diameter of segment III. The triommatidia is merged with the compound eye, so there is no distinct ocular tubercle. The apical rostral segment (RIV+V) is slender and pointed with six short secondary hairs, and is about 1.2 times the length of the second hind tarsal segment (HTII); (cf. Coloradoa tanacetina, which has RIV+V less than 1.1 times HTII). The dorsum bears numerous fan-shaped hairs (cf. Coloradoa tanacetina, which has very small dorsal hairs weakly club-shaped, or with only slightly expanded apices). The siphunculi vary in pigmentation from dusky just at the apex to almost wholly dark; they are symmetrically swollen just before apex, and are 0.17-0.20 times the body length (cf. Coloradoa tanacetina, which has siphunculi 0.13-0.18 times the body length). The siphunculi are almost smooth on the basal part, compared to the coarsely imbricated distal part (cf. Coloradoa artemisiae, which has siphunculi that are coarsely imbricated on both the basal and distal parts. The cauda is pale or dusky, oblong, triangular, not constricted, with 4-5 hairs. The body length of adult Coloradoa rufomaculata apterae is 0.9-1.5 mm.
Note: The red and yellow spots which gave the aphid its scientific name are not visible in clarified mounts. The red spots are the eyes of developing embryos.
Images above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20).
The alate Coloradoa rufomaculata (not pictured) is green with pale marginal and intersegmental sclerites. The antennae and tips of legs are black, and the siphunculi and cauda are dark. The antennae have 6-10 secondary rhinaria on segment III, 6-10 on IV and 0-3 on V.
The image below shows a clarified mount of a Coloradoa rufomaculata apterous vivipara.
Image above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20).
Coloradoa rufomaculata is monoecious on chrysanthemum and Artemisia species, especially florists chrysanthemum (nominally Dendranthema × grandiflorum) and Indian chrysanthemum (Chrysanthemum indicum). The aphid has the peculiar habit of settling in the notches of the serrated leaves of the host plant. In India it is often found in association with Aphis gossypii and Macrosiphoniella sanborni. Oviparae and males have been reported from Australia, but most populations are anholocyclic. Coloradoa rufomaculata has a cosmopolitan distribution including North America, Europe, central and east Asia and Australia, but is mainly found in glasshouses in cold temperate climates.
Other aphids on the same host
Coloradoa rufomaculata has been recorded from 2 chrysanthemum species (Chrysanthemum coronarium, Chrysanthemum indicum).
Coloradoa rufomaculata has been recorded from 9 artemisia species (Artemisia absinthium, Artemisia annua, Artemisia argyi, Artemisia capillaris, Artemisia gmelinii, Artemisia indica, Artemisia ludoviciana, Artemisia princeps, Artemisia vulgaris).
Damage and control
Coloradoa rufomaculata is known to transmit three plant viruses, including one affecting chrysanthemums (chrysanthemum virus B). Miller & Stoetzel (1997) report that the aphid can become problematic on glasshouse chrysanthemums in the USA.
Khan et al. (2021) review insect pest and disease management on chrysanthemum in Bangladesh. The major aphids which severely infest Chrysanthemum indicum are Aphis gossypii, Aphis fabae, Coloradoa rufomaculata, Macrosiphoniella sanborni and Myzus persicae. Aphids feed from the phloem of the vascular bundles of early shoots and leaves. Plant parts affected by aphids will wilt, discolor or deform. Aphids are regularly found in groups on plant tips, shoots of new growth or flowers. Collection and destruction of the infested leaves, twigs, inflorescences and pods of the chrysanthemum crop, encouragement of predators, and use of Neem leaf extract can often effectively manage the insect pests. For severe infestations, insecticides such as dimethoate and imidacloprid may be required to reduce the aphid population significantly.