Pemphigus betae
| Pemphigus betae | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Family: | Aphididae |
| Subfamily: | Eriosomatinae |
| Genus: | Pemphigus |
| Species: | P. betae |
Pemphigus betae, also known as the sugarbeet root aphid, is a species of gall-forming aphid that forms galls specifically on the commonly found Narrowleaf Cottonwood (aka the Willow-leaved Poplar tree), Populus angustifolia. Sugarbeet root aphids have been found in North America and Europe. They infect sugarbeets, but also other plants like tablebeets and Swiss chard. Their size has been likened to that of a pinhead, and are pale white-yellow in color. Sugarbeet root aphids have soft bodies that are bulbous in shape, with mandibular parts that can pierce and suck and paired abdominal tubes that point backwards, and come in both winged and wingless forms. They are known for their consequential effects on agriculture due to infestation of plants, and efforts to control the pests have proved to be difficult.
Sugarbeet root aphids are characterized to be as small as pinheads, and take on a pale white-yellow color. They have globular bodies that are soft, with mandibular parts that allow them to pierce and suck and paired abdominal tubes that point backwards. There are both winged and wingless sugarbeet root aphids.
The sugarbeet root aphid is found throughout the major sugarbeet growing areas of North America, (in the Nearctic area) and has infested areas in Texas, California, Michigan, and Alberta, Canada; it has also been introduced in Europe. The aphid has been recorded at only a few sites in Europe, but the data on other species of aphids suggest that they can increase their range of occurrence, often quickly and in an invasive manner. Infestations are usually more severe under dry soil conditions, either due to dry years in dry land conditions in the upper Midwest of the United States, or to using less water in the irrigated areas of the West and Southwest United States. Infestations are usually the most severe during July and late August.
Most species of aphids, at all stages of development, move about over the surface of their host plants and even between adjacent plants. These local movements result in slow diffusive dispersal. In contrast, aphids also show persistent 'straightened out' movements during which their vegetative responses are depressed; these movements are a means of transport over larger distances. Local 'trivial' movements and distant 'migratory' movements can be recognized, and it is possible that they are the extremes of a continuum of movement that disperses all species of aphids.
Dispersal creates a relatively high mortality rate for sugarbeet root aphids. Additionally, alate aphids incur other disadvantages: if aphids fly then they may incur an additional cost in that their potential fecundity is further reduced and there is a further delay in the onset of reproduction. The combined effect is a marked reduction in reproductive potential and rate of increase. Although dispersal results in the colonization of suitable plants, it is not always clear what advantages there are in dispersing except from annual plants that are about to die. As dispersal can be costly in terms of fecundity or survival, or both, then sugarbeet root aphids are likely to delay departure until host quality falls below the average expectation for the habitat.
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Wikipedia