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The Convict cichlid (Amatitlania nigrofasciata) is a fish species from the family Cichlidae, native to Central America, also known as the zebra cichlid. Convict cichlids are popular aquarium fish and have also been the subject of numerous studies on fish behaviour.

Taxonomy
Albert Günther originally described the species in 1867 after Frederick DuCane Godman and Osbert Salvin collected specimens in Central America. In 2007, the species was moved from the genus Archocentrus to a new genus, Amatitlania based on Juan Schmitter-Soto's study of Archocentus species. However, a 2008 study led by Oldrich Rican proposed moving the species in Cryptoheros and Amatitlania, including Amatitlania nigrofasciata into the genus Hypsophrys.

The convict cichlid displays significant color variation across its range. Some of these regional variants are now considered different species. In the cichlid-keeping hobby, Rusty Wessel collected one such fish Amatitlania siquia "Honduran Red Point" from a stream in Honduras. The Honduran Red Point Convict ranges from Atlantic Honduras south to Costa Rica. Other new species formerly included in A. nigrofasciata are:


 * Amatitlania coatepeque, from Lake Coatepeque in El Salvador, and
 * Amatitlania kanna, from Panama's Atlantic coast

The type species, A. nigrofasciata, which used to cover all these species, is restricted to the northern population ranging from El Salvador to Guatemala on the Pacific coast and from Honduras to Guatemala on the Atlantic coast.

A number of synonyms exist for this species including: Archocentrus nigrofasciatus, Cichlasoma nigrofasciatum, Cryptoheros nigrofasciatus and Heros nigrofasciatus.

Etymology
The common name convict cichlid is, like the species name, derived from the vertical black stripes on the fishes body and their similarity to the striped prison uniforms of British convicts. Similarly, the species epithet nigrofasciatus literally means black-striped.

Description
The wild-type of the species has 8–9 black vertical bars on a blue-grey body, along with a dark blotch on the operculum. Juvenile convict cichlids are monomorphic until they reach sexual maturity. The male is mostly gray with light black stripes along the body. Males are larger than females, and they have more pointed ventral, dorsal and anal fins which often extend into filaments. In addition, older males frequently develop vestigial fatty lumps on their foreheads. Unusually for fish, the female is more highly coloured. She has more intense black bands across the body, and pink to orange colouration in the ventral region and on the dorsal fin. The average standard length of mature males in the wild range from 6.3–6.6 centimeters, while breeding–sized females range from 4.2–5.5 centimeters. The maximum standard length has been reported to be 10 centimeters, with total length near 12 cm. Body weight has been reported to range from 34 –. Selective breeding has resulted in a leucistic strain of convict cichlids, in which the dark barring of the wild type is absent. These are also known as white convicts, pink convicts, gold convicts and A. nigrofasciata "Kongo",. The leucistic colouration is caused by a mutation in an autosomal gene and is recessively inherited.

Range and habitat
Convict cichlids are endemic to the lakes and streams of Central America. In particular, the species occurs along the eastern coast of Central America from Guatemala to Costa Rica, and on the western coast from Honduras to Panama. Convict cichlids prefer moving water, and are most frequently found in habitats with cover in the form of rocks or sunken branches. At four natural habitats of the convict cichlid in Costa Rica, the pH was found to range from 6.6–7.8, while GH ranged from 63 to 77 ppm Calcium carbonate. The daily water temperature ranged from 26 –. Convict cichlids can be relatively tolerant of cool water, an ability which has allowed the species to colonise volcanic lakes at elevations of 1500 m.

Feral populations
The species also occurs outside its natural range in Australia: in the warm effluent of power stations in Victoria, and in tropical Queensland. In addition to Australia, the species has been introduced to Réunion, Japan, Mexico, Taiwan, and the USA.

Feeding
In natural habitats, the species has a diet composed of various prey, including crustaceans, small fish, insects, worms, plants and algae. This varied diet is a result of the fish's ability to protrude its jaw 4.2% of standard length. Inferior social status and associated stress can affect digestive function in convict cichlids.

Life Cycle
The species can reach sexual maturity as young as 16 weeks, though sexual maturity more commonly occurs at 6 months. Sexually mature convicts form monogamous pairs and spawn in small caves or crevices. In the wild, the fish excavate caves by moving earth from underneath large stones. Females lay the eggs on the upper or side surfaces of the cave to which they adhere.

Like most cichlids, convicts brood (exhibit parental care of) both eggs and free-swimming fry. The eggs hatch approximately 72 hours after fertilization, and during that time the parents expel intruders and potential egg predators from around the nest. They also fan the eggs, moving water with their fins over the clutch to bring oxygen to the eggs. They fan the eggs both day and night; at night they use their sense of smell to recognize the presence of the eggs in the dark, and they keep their pelvic fins in contact with the eggs to remain at the right distance for fanning. At night the parents also recognize each other via their sense of smell, and they sniff out and react to the presence of potential predators in or near the nest.

After hatching, a further 72 hours is required for the larvae to absorb their yolk sacs and develop their fins prior to becoming free-swimming fry. While in this free swimming stage, fry forage during daylight in a dense school and return to the cave or crevice for the night. Like other cichlids, the parents also retrieve their young just before dark, sucking up three or four fry at a time into their mouth, swimming back to the nest, and spitting the young into it. The parents do this in anticipation of night arrival, using an internal time sense to know that night is approaching, as shown by laboratory experiments in which convict cichlids continued to retrieve even before nights that were not preceded by any signal such as dim light. During the night, the fry bunch up at the bottom of the cave or nest, where the parents fan them.

Both parents remain involved in guarding the fry from brood predators and engage in behaviors to assist feeding such as moving leaves or fin digging (digging up the substrate with their fins). Brood care of eggs, larvae and free-swimming juveniles in the wild can last 4–6 weeks, and occurs only once per season for the majority of females. In contrast, females in aquariums are known to breed many times per year with short intervals of 12–13 days between broods, as long as suitable rocks or similar surfaces are available for them to lay their eggs on.

Mating System
Convict cichlids are also serially monogamous, so pair bonds may form first before they establish a territory together, or the male and female may each individual obtain a territory before pairing with each other. Because the convict cichlids are also substrate-brooding, this territory will include a breeding site for the deposition of eggs.

Sexual Selection
The effect of population density on sexual selection for convict cichlids has been studied. When nest density was greater, the females tended to be larger, which is more accurately explained by density-dependent mate preference and mating competition, as opposed to predation and resource competition. Moreover, as the two nest density regimes were compared, with one high and one low, there was no significant difference in brood survival between the two; however, the convict cichlids did prefer to breed farther away from each other, not in close proximity. This indicates that there are some other costs with breeding in an environment with high population density, an example being energy loss because of the resulting increased aggression when guarding territory.

The female's preference for the male mate has also been examined, in accordance to the male's size and fighting ability. The female cichlid always chooses the larger of the two males if the smaller male is next to the larger male, and if the larger male defeats the smaller male in a fight. If the males are not viewed together at the same time for a comparison to be drawn by the female, the female has no particular preference. Females do benefit by mating with a larger male, as it has been shown that larger males can raise more offspring to independence, are better at chasing predators that might attack offspring, and are better at competing for breeding sites. Male size may act as a more effective indicator of aggression, which may thus repel intruders before they can come closer to the offspring. It has been shown that individuals of significantly greater size relative to their opponent often win fights without much physical contact.

Parental Roles
Convict cichlids are a biparental species, so the parents will usually cooperate by carrying out tasks specific to their individual parental roles when raising their offspring. This is common in cichlid fish, and studies have shown coodination between the female and male. The female tends to remain with the brood and perform activities involving the brood, whether it be fanning the eggs or mouth-brooding the larvae, whereas the male tends to patrol the area to chase intruders and defend from predators. Both parents are able to carry out all of the parental care tasks to a certain extent; however, because they are biparentally custodial, each sex will still focus on a specific set of behaviors in particular, which is susceptible to change during the brood cycle. In fact, it is observed that when one of the mate is removed, either parent is still able to raise the offspring independently by having the capacity for all the parental behaviors. As the young offspring grow and become free-swimming fry, the parental activities are distributed more equally between the parents, which appears to be typical behavior in other types of cichlids as well.

The different ways in which this biparental sex role specialization can be influenced was studied, by manipulating the presence and absence of the mate, as well as the presence and absence of an intruder. The former variable was considered because the specialization of parental roles only occurs when both parents are present, while the latter variable was considered because it is thought that biparental care in these cichlids was an evolutionary consequence of the protection of offspring from intruders. When both mates are present with no intruder, both parents may stay with the offspring by resembling single parents because each parent is addressing only the offspring and not its mate, or one parent may be concentrated on activities associated with the offspring while the other parent concentrates on patrolling and defending the area. Under these isolated conditions, a more equal sharing of parental behaviors tends to occur. However, when both mates are present and an intruder is introduced, the male spends more time chasing intruders while the female remains with the offspring more. When the intruder is present but the pair is not intact and each individual is by themselves, the widowed male leaves the offspring tends to leave the offspring unattended and instead attacks the intruder or predator. Therefore, the conclusive finding is that the male rarely remains with the offspring when the female is absent, and the female rarely confronts the intruder when the male is absent.

Brood Adoption
Convict cichlids may show extended biparental care ,and adopt unrelated young of the same species of similar or smaller body size compared to their own biological offspring. The parents may benefit by adopting smaller young by taking advantage of the dilution effect, which is when the risk of predation for an individual is reduced because the group size is larger. Another reason that has been considered is that foreign young that are larger than the biological offspring may be a direct predatory threat to them. However, it has been shown that as the biological offspring develops and become stronger swimmers, the parents were les s active about rejecting larger foreign young, but when they did reject, oftentimes foreign young were rejected before they were large enough to be perceived as a direct threat to the biological offspring. Thus, it can be concluded that the brood adoption and rejection relies more heavily on the protection of the biological offspring from differential predator instead of from larger adopted cichlids.

Aggressive Behavior
Convict cichlids are known to be highly aggressive, possessing a variety of complex behaviors and adaptations, which have been suggested to be a result of environmental conditions, individual development, and trait variation. Due to their aggressive nature, cichlids are popularly studied to investigate the factors that may potentially cause their behavior. Convict cichlids usually demonstrate their aggressive behavior by biting and chasing, which entails bursts of high speed targeted at the intruder, and also show their aggression via their body size.

It has been shown that environmental parameters like changes in temperature and prior residence may affect the cichlid's territorial aggression. The convict cichlids are more aggressive at 30°C as opposed to 26°C, which may be explained by the fact that convict cichlids tend to set up their breeding sites and spawn at 30°C.

Aquarium care
The aquarium should be decorated to mimic the natural environment and include rocks and artificial caves for breeding. The species is an unfussy omnivore and most types of prepared fish foods are readily accepted. The species also consumes aquatic plants. Convict cichlids are aggressively territorial during breeding and pairs are best kept alone. Brood care is reduced in aquarium strains. Due to the species' tendency to dig, external filtration is superior to undergravel filter systems. Its relatively small size, along with ease of keeping and breeding, make the convict an ideal cichlid for beginners and advanced aquarists alike interested in observing pair bonds and brood care.

Reversible Male Types
The males of the Astatotilapia burtoni come in two phenotypes that are reversible. They may be dominant, territorial males that have bright coloration, have aggressive behavior while defending territory, and have an active role in sexually reproducing with the females; on the other hand, others are subordinate and non-territorial, having the similar coloration as the females, possessing submissive behaviors, rarely taking the initiative to pursue female counterparts, and being reproductively suppressed due to regressed gonads. These two starkly contrasting male phenotypes are reversible, meaning that the males can readily switch between being territorial and non-territorial based on the social environment they are in. These transitions between different social roles cause several changes in the brain and reproductive system, meaning that the social transformation affects them in behaviorally and physiologically. For example, if a territorial male is placed with an individual that is significantly larger in size, it will then socially transform into the non-territorial type fairly rapidly, and this change can be detected by its following behavior and coloration. The change in reproductive competence, however, occurs much later, about three weeks after the formerly territorial male loses its territory to the larger fish. In regards to the other social transition, when a non-territorial male becomes the territorial type, it will almost immediately exhibit aggressive behavior and an eyebar, while the physiological changes will follow in about one week. Several studies have been done in order to pinpoint the biological basis on which this occurs, and they suggest that the stress hormone cortisol may have a direct role in the social status, because the cortisol may change the biological priorities of the cichlid's system. Under chronic stress, the animal may experience reproductive regression (as shown in the territorial's male shift to the non-territorial type) as a result of the body's efforts to combat the stressor as opposed to using the metabolic energy for long-term goals like reproduction. Moreover, studies have also shown that the male cichlid's social phenotype directly influences the hormone levels of testosterone and 11-ketotestosterone. Plasma concentrations of these androgens in both the territorial males and non-territorial males were measured and assessed, and it was found that the territorial males have drastically higher plasma concentrations of both hormones. The cichlid males' behavior of shifting between dominant and subordinate states as a result of the social environment can also be due to the females of that context, for females may alternate between reproductive states as well, but independently of social conditions. Females use a complex integration of cues in order to make their mate preferences, which may be from genetic factors, learned behaviors, and hormone levels. They can socially transform between a gravid reproductive state, which is egg-bearing, and a non-gravid reproductive state, and it was shown in a study that the mating preferences of the female highly depended on the reproductive state in which the female was in. Gravid female cichlids will prefer to spend time with the dominant male type instead of the subordinate male type, whereas the non-gravid females do not have a preference for either one. This may be explained by the fact that because for spawning to occur, the gravid females must be courted by the dominant males, suggesting that gravid females' preference for dominant males is a behavioral priming mechanism.

Maternal Mouthbrooding
Astatotilapia burtoni is a lekking species, so the dominant males will have male displays of courtship in order to attract and lure females that are passing by. Once the females are enticed and enter the male's territory to spawn, after spawning, the females will rear the young in their mouths: a behavior called mouthbrooding. Astatotilapia burtoni are maternal mouthbrooders, so the female cichlids care for their offspring by incubating them in their mouths. After about two weeks of incubation have passed, the females will release their young. Following this, after several more weeks have passed, the female cichlids will have recovered physiologically enough to be able to spawn again. Maternal mouthbrooding is recognized to have an impact on hormones and reproductive cycles for the female cichlids, but the effects as a result of neural processing and food deprivation are not known. A study particularly focused on this subject matter examined the effects that maternal mouthbrooding may have on a wide variety of physiological practices, in order to see if they are consequences of food deprivation, and indeed it was found that many of the changes (not all) are explained by food deprivation.

Acoustic Signals
Many animals use multimodal communication, having multiple sensory modalities at their disposal for reproductive interactions, and the Astatotilapia burtoni has been used as a model to study the production of the wide variety sexual signal types. Astatotilapia burtoni incorporate multiple sensory systems, including chemosensory, visual, acoustic, to be able to socially interact in their complex manner. East African cichlids in general are especially known for their vibrantly colored bodies and the role that coloration plays in courting and mating, but the Astatotilapia burtoni is known to be phenotypically distinct in its use of a completely different form of sensory communication: acoustic communication. Sounds and the corresponding behaviors of the male sex of these particular African cichlids have been studied while observing the female mate preference, and behavioral experiments demonstrated that acoustic information does indeed play a significant role in sexual reproduction. This reliance on non-visual sensory information in order to coordinate complex social behaviors indicates that acoustic signaling is important for the Astatotilapia burtoni. This suggests that there are internal cues in these cichlid fish that can significantly change the way in which the fish respond to auditory signals because the physiological state of the fish can directly impact the perception of the auditory signals. Thus, more efforts have been made to understand how the females perform sexual selection by closely examining the signaling systems and how they relate to the neural processing in the fish to result in such behaviors. A particular study showed that dominant males will issue auditory signals in order to court females, and that these courtship sounds are similar to those that they themselves could perceive. The study found that the broadband sounds that the dominant males produced were associated with body quivers, suggesting that the sounds were produced intentionally for courting and not a by-product of the quivers as not all the quivers were accompanied by sounds. The data also suggested that auditory perception of the Astatotilapia burtoni changes in accordance to the reproductive cycle of the fish. This may be potentially due to the levels of the circulating hormones.

Description
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.

Habitat
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
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.

Life cycle
In the spring, a female nymph (also known as a stem mother) emerges from an overwintering egg and initiates a gall on one of the leaves of the Populus tree. The gall forms around the stem mother, who begins to reproduce parthenogenically while feeding on the leaf's phloem sap. Each stem mother is capable of creating up to 300 progeny per gall. The gall occupants develop wings in the middle of the summer and disperse from the gall to deposit their larvae in the ground. These larvae colonize and feed on the roots of nearby Chenopodiaceae plants for the rest of the summer. In the summer, they form alate migrants that fly back to the Populus tree and asexually produce sexual males and females whose sole purpose is to mate, as they lack mouthparts to feed. The product of sexual reproduction is a single egg in each female which is deposited in the tree's bark and left to overwinter.

Leaf colonization
Sugarbeet root aphids are closely synchronized with their hosts Populus augustifolia, with the majority of stem mothers colonizing leaves within three days after the leaf buds burst. There is intense competition between Pemphigus stem mothers over leaf choice - galls formed on larger leaves have higher stem mother weight, more aphids overall, and a lower probability of being aborted. Moreover, galls formed closer to the leaf stem-and thus closer to the source of nutrients flowing into the leaf-also benefit in the same way. During the aphids' emergence in the spring, large Populus leaves are colonized first. Once a stem mother forms a gall, she is more reluctant to move to a new leaf even if the current one withers, though the ability to colonize a large, healthy leaf close to its stem is crucial in ensuring an aphid's reproductive success.

On average, stem mothers distribute themselves among the leaves of a Populus tree according to the ideal free distribution model. Stem mothers sharing a leaf have to split the available resources, and this sharing comes at a cost to the stem mother's reproductive success. Two stem mothers sharing a leaf spend a significant amount of their time engaging in territorial behavior instead of feeding or gall forming. Thus, stem mothers sharing a leaf produce less offspring than single stem mothers on leaves of the same size. When one stem mother is removed from a shared leaf, the reproductive success of the remaining occupant(s) rise accordingly. Some stem mothers choose to settle alone on smaller leaves instead of sharing a larger leaf with another individual. This creates a scenario where, on average, there is no difference between the reproductive success of stem mothers occupying leaves singly and stem mothers sharing leaves with other individuals.

As a result of the importance of leaf choice in their reproductive success, sugarbeet root aphid stem mothers are highly territorial and will compete with each other for the chance to form galls at the bases of the largest leaves. This competition usually takes the form of kicking and shoving contests; two stem mothers will align rear-to-rear and push against the other forcefully using their hind legs. The winner of these contests then settles closest to the leaf base, and the loser settles more distally. If the basal stem mother dies or is removed, the distal stem mother often moves down to the base of the gall to replace her. These territorial contests are unusually long, and can span the course of several days. A side effect of this intense territorial competition is the creation of a "floater population" of unsettled stem mothers searching for unoccupied leaves.

Stem mothers and gall choice
Sugarbeet root aphid stem mothers induce gall formation in the leaf by probing the leaf tissue with their stylets. This leads to the formation of a small depression on the leaf, which eventually closes up over the stem mother and forms a gall. The extent of the probing activity dictates gall size, and removing the stem mother early on in the process leads to the formation of an unclosed, rudimentary gall. The extent of probing activity is correlated with the aphid's reproductive success. The probing activity may also serve a secondary purpose in helping the aphid determine leaf size. Leaf size is an important factor in determining what leaf a stem mother chooses to develop a gall on, but at the time of leaf colonization, leaves that are being colonized are only a tenth to a quarter of their mature size. It has been suggested that, during the probing of the leaf, the stem mother gauges the chemical environment of the leaf and uses that as a predictor of final leaf size and suitability as a gall site. Aphids possess chemosensory organs, allowing them to respond to a variety of stimuli from the plant, both those of the volatile variety (olfaction) and non-volatile variety (taste). Once the aphid is on a plant, it tests the surface of plant with its antennae and probes the plant with its mouth parts. The antennae contains many sensilla, allowing them to sense tactile and chemical stimuli.

Stem mothers and their progeny
At the onset of autumn in temperate regions many species switch to the production of sexual forms, with each clone producing both egg-laying females and males. This switch is triggered by the longer nights in the autumn. Both sexual males and sexual females are produced parthenogenetically in response to external and/or internal cues, such as the amount of food present, the amount of daylight, and the quality of the leaf. However, sugarbeet root aphids are also capable of reproducing sexually. Aphids predominate in the temperate regions of the world; to overwinter in a cold-resistant resting stage, the fertilized egg, is an adaptation to temperate conditions. One possible short-term advantage of sex is that it generates siblings with a range of genotypes, and a range is more likely to include the fittest genotype for a particular patch than the single genotype of an asexual sibling-ship would. Thus, genetically diverse siblings could have more 'elbow-room' as they are potentially capable of exploiting more than one kind of leaf-patch.

Interaction with the leaf
The benefits of settling basally are significant, with basal stem mothers producing 49-65% more offspring than their distally settled counterparts. The benefits of settling basally relate to the aphid's ability to manipulate the plant's food resources. The galls formed by sugarbeet root aphids act as physiologic sinks, diverting and intercepting the plant's normal transport of resources and nutrients. 14C labeling experiments have shown that their galls intercept resources being transported from the midvein to the distal parts of the leaf. In addition, these galls are able to divert 14C from neighboring leaves. One study showed that, on average, 29% of the 14C accumulating inside a basal gall was supplied by a neighboring leaf and not the leaf the gall itself was on. In contrast, neighboring leaves only supplied 7% of a distal gall's 14C, illustrating the importance of settling basally.

Tree colonization
After emerging in the autumn, the migrant forms of sugarbeet root aphids seek out Populus trees to colonize. These migrant forms are short-lived, and usually die within 12 to 48 hours. In selecting trees to colonize, the autumn migrants of sugarbeet root aphids prefer to colonize larger trees over smaller ones, and are likely to use simple cues such as tree crown size or tree resistance to colonization to decide on which trees to colonize. Despite the importance of leaf size to stem mothers, autumn migrants do not appear to take leaf size into consideration when choosing a tree to colonize.

Agricultural impact
Sugarbeet roots have become a common crop for sucrose production in the northern United States. A concern among farmers is the impact that sugarbeet root aphids can have on these crops, which are colonized by and used as secondary hosts for sugarbeet root aphids.

Effect on crops
The lifecycle of sugarbeet root aphids involves primary and secondary host plants. Galls are formed on the primary host, cottonwood, in the spring by the stem mother. Her wingless offspring, called apterae, feed on the gall until giving rise to winged individuals called alatae. These alatae break out of the gall and colonize the roots of their secondary hosts, sugarbeet.

These individuals then suck the sap from the sugarbeet roots, which causes them to lose their color, wilt, and die. Infestation is apparent where they appear as circular patches in which plants and leaves are wilted and dying. During dry years when cracks form in the soil, the secondary host roots become much more accessbible to the aphids, which can lead to severe yield loss.

Economic costs
The economic impact of sugarbeet root aphids on sugarbeet crops in southwestern Minnesota was studied during the 1990 and 1991 growing seasons. The effects of infestation on yield and quality of sugarbeet root showed that loss of sucrose content in the plant was the primary reason for reduced quality. In addition, yield rates were significantly higher in 1991 due to higher levels of precipitation.

Further studies have shown that sugarbeet root aphid infestation is most prevalent in the upper Midwest during drought years, and in the southwest during times of low irrigation. Sometimes, despite dry conditions, cool weather can decrease the prevalence of sugarbeet root aphid infestations.

Pest control and management
Although certain control methods are effective on other root-feeding arthropods, control measures for sugarbeet root aphids are more difficult. Crop rotation and simple foliar and postemergence insecticides are usually ineffective. However, Knox Out 2FM and Counter 15G have proven to be effective in containing infestations, although some states, such as California, currently have no chemicals registered for use on the sugarbeet root aphid. Biological controls, such as introduction of fungal diseases or natural predators, may also serve as an effective means of pest control. Although it is unlikely that biological controls are fully capable of controlling sugarbeet root aphid populations, future research may increase their role in management.

To properly manage damaged and infested areas, it is necessary to thoroughly work these areas and destroy plants left in the ground for the following harvest. Weeds in the infested areas should be destroyed, equipment should be cleaned, and infested fields should not be used for at least three years. Water stresses should be avoided in order to prevent yield loss due to water-stressed sugarbeets.