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Silverleaf whitefly

Article author: Erfan Vafaie
Most recently reviewed by: Pat Porter & David Kerns & Suhas Vyavhare (2018)

Common Name(s): Silverleaf Whitefly, Sweetpotato whitefly

Description

The silverleaf whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a global pest of many economically important host plants (Simmons et al. 2008) such as eggplant, tomato, sweet potato, cucumber, garden bean (Tsai & Wang 1996), cotton, and poinsettias, to name a few. Similar to other sucking insect pests, silverleaf whiteflies reduce plant vigor, growth, and can even cause mortality by piercing plant tissue and feeding on plant phloem (Bryne & Miller 1990). Whiteflies excrete waste as a sugary solution, known as honeydew. Excessive honeydew can result in inoculation of a complex of fungi, resulting in a black layer or crust forming on the surface, commonly referred to as sooty mold. In addition to causing detrimental damage by feeding, B. tabaci has been recorded to vector more than 100 plant viruses (Jones 2003), which can result in rapid widespread crop loss. Some of these viruses in Texas include Cucurbit leaf curl virus (Brown et al. 2000) and cucurbit yellow stunting disorder virus (Kao et al. 2000).

Adult whiteflies resemble very small (1 mm or 3/64-in) white moths. When disturbed, adult whiteflies will often leap off the plant and fly a short distance before landing on a nearby surface. Whitefly nymphs, especially younger nymphs, can be hard to see with the naked eye. Whitefly nymphs often blend with the leaf due to their color and relatively flat shape. The final nymph instar is often referred to as a pupa, when they become darker yellow color and are more round, making them easier to distinguish on the leaf. Once they emerge as adults, their shed ‘skin’ stays on the leaf, known as an exuvia. The exuviae stay on the leaf and resemble a small empty shell.

Adult silverleaf whiteflies can be confused for other whiteflies that may occur in Texas, with two other common ones being the badedwing whitefly (Trialeurodes abutiloneus) and greenhouse whitefly (Trialeurodes vaporariorum).

Origin and Distribution

Silverleaf whiteflies are considered a global pest, however there are certain biotypes or species that are more prevalent in different parts of the world. Texas has populations of both MEAM1 (B biotype) and MED (Q biotype) whitefly.

Life Cycle

Whiteflies are closely related to mealybugs and scale insects. Female adult whiteflies lay eggs, often in a circular pattern as result of the female using her feeding proboscis as a pivot while laying eggs. Eggs are pear-shaped and approximately 0.2 mm long (CABI MEAM1). On cotton, eggs take between 5 to 22.5 days to emerge as crawlers when held at 16.7ºC (62F) or 32.5ºC (90.5) (Butler et al. 1983), respectively. After emerging from the eggs, a mobile stage known as “crawlers” find a place nearby to settle. Once settled, whitefly nymphs are considered rather immobile until after metamorphosis. Bemisia tabaci undergo four instar stages before pupation and becoming a winged adult. The total development time from egg to adult varies from 16.6 days at 30ºC (86F) to 65.1 days at 14.9ºC (59F) in cotton (Butler et al. 1983). Adult females lay approximately 72 – 81 eggs and survive an average of 8 to 10.4 days in controlled studies (Butler et al. 1983).

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Silverleaf whitefly taxonomy is currently under revision, but it is generally agreed upon that there are specific groups of silverleaf whiteflies that exhibit different host plant preferences, reproductive rates, and resistance to insecticides. Originally, it was thought that silverleaf whiteflies were composed of several different ‘biotypes’, a couple well-known ones including the “B” (MEAM1) and “Q” (MED) biotypes, but now has been proposed to be made up of at least 34 morphologically indistinguishable species (Tay et al. 2012). The MEAM1 whiteflies have greater reproductive potential than the MED whiteflies, however the MED whiteflies are resistant to several different insecticides, such as pyriproxyfen and imidacloprid. Growers are encouraged to either use biological control to prevent further rise of resistance to insecticides, or rotate between insecticides that are known to be effective against both MEAM1 and MED whiteflies. See “Related Publications” below for more information.

Whitefly populations can be monitored using yellow sticky cards or searching the undersides of leaves for eggs, nymphs, pupae, exuviae, or adults. Look for other signs of infestation, such as honeydew, sooty mold, or chlorosis.

In many regions of Europe and North America, silverleaf whiteflies in protected culture (i.e. greenhouses) are managed through regular releases of biological control agents. In the USA, commercially available biological control agents that have demonstrated potential management of silverleaf whiteflies include Eretmocerus eremicus (Hoddle and van Driesche) and Amblyseius swirskii (Calvo et al. 2010).

Insecticidal management of silverleaf whiteflies are highly dependent on commodity, location, setting, and thresholds. Some active ingredients that have demonstrated efficacy against both MEAM1 and MED silverleaf whiteflies include:

  • Abamectin
  • Abamectin + Bifenthrin
  • Acetamiprid
  • Beauvaria bassiana
  • Cyantraniliprole
  • Dinotefuran
  • Isaria fumosorosea
  • Horticultural Oil*
  • Insecticidal Soap*
  • Pyridaben
  • Pyrifluquinazon
  • Spiromesifen
  • Spirotetramat
  • Thiamethoxam

(Kumar et al. 2017)
*Beware of application in extreme heat and exposure to sun. Can cause leaf burn/phytotoxicity.

For more information, consult one of our related publications below for whitefly management specific to your situation.

Related Publications

CABI Bemisia tabaci (MEAM1) fact sheet: https://www.cabi.org/isc/datasheet/8925#8440C199-FEDE-40E6-AED0-E7C195DC4E5B

CABI Bemisia tabaci (MED) fact sheet: https://www.cabi.org/isc/datasheet/112682

Byrne, David N. (1991). Whitefly biology. Annual Review of Entomology, 36: 431 – 457.

Suhas et al. (2018). Managing Cotton Insects in Texas. Texas A&M AgriLife Extension. https://agrilife.org/extensionento/resources/management-guides/managing-cotton-insects-in-texas/other-pests/

Kumar et al. (2017). Whitefly (Bemisia tabaci) management program for ornamental plants. UF/IFAS Extension. https://mrec.ifas.ufl.edu/lso/bemisia/Documents/EDIS-Whitefly-Management-Program.pdf

Citations

Brown et al. (2000). Cucurbit leaf curl virus, a new whitefly transmitted geminivirus in Arizona, Texas, and Mexico. The American Phytopathological Society, 84(7): 809.

Butler et al. (1983). Bemisia tabaci (Homoptera: Aleyrodidae): Development, oviposition, and longevity in relation to temperature. Annals of the Entomological Society of America, 76: 310 – 313.

Byrne & Miller (1990). Carbohydrate and amino acid composition of phloem sap and honeydew produced by Bemisia tabaciJournal of Insect Physiology, 36: 433 – 439.

CABI Bemisia tabaci (MEAM1) fact sheet: https://www.cabi.org/isc/datasheet/8925#8440C199-FEDE-40E6-AED0-E7C195DC4E5B

Calvo et al. (2011). Control of Bemisia tabaci and Frankliniella occidentalis in cucumber by Amblyseius swirskii. 56(2): 185 – 192.

Hoddle, M. and van Driesche, R. G. (1999). Evaluation of inundative release of Eretmocerus eremicus and Encarsia formosa Beltsville strain in commercial greenhouses for control of Bemisia argentifolii (Hemiptera: Aleyrodidae) on poinsettia stock plants. Biology and Microbial Control, 92(4): 811 – 824.

Jones D (2003). Plant viruses transmitted by whiteflies. European Journal of Plant Pathology, 109: 197 – 221.

Kao et al. (2000). First report of Cucurbit yellow stunting disorder virus (genus Crinivirus) in North America. The American Phytopathological Society, 84(1): 101.

Kumar et al. (2017). Whitefly (Bemisia tabaci) management program for ornamental plants. UF/IFAS Extension. https://mrec.ifas.ufl.edu/lso/bemisia/Documents/EDIS-Whitefly-Management-Program.pdf

Simmons et al. (2008). Forty-nine new host plant species for Bemisia tabaci (Hemiptera: Aleyrodidae). Entomological Science, 11: 385 – 390.

Tay et al. (2012). Will the real Bemisia tabaci please stand up? PLoS ONE, 7(11): 7 – 11.

Tsai & Wang (1996). Development and reproduction of Bemisia argentifolii (Homoptera: Aleyrodidae) on five host plants. Environmental Entomology, 25(4): 810 – 816.

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Crapemyrtle bark scale

Article author: Erfan Vafaie, Mike Merchant, Mengmeng Gu
Most recently reviewed by: Janet Hurley (2018)

Common Name(s): crapemyrtle bark scale

Description

The crapemyrtle bark scale, Acanthococcus (=Eriococcus) lagerstromiae (Kuwana), was first confirmed in the USA in 2004 in the landscape near Dallas (TX), although it was likely introduced earlier. The scale is a sucking insect that feeds on the phloem (sap) of plants. As it feeds, it excretes a sugary solution known as “honeydew” (similar to aphids, whiteflies, and other sucking insects). Heavy infestations of crapemyrtle bark scale produce sufficient honeydew to coat leaves, stems and bark of the tree. This honeydew, in turn, will eventually turn black as it is colonized by a concoction of fungi, called sooty mold. Although crapemyrtles rarely die as a result of crapemyrtle bark scale infestation, the sticky leaves and black trunks greatly reduce the attractive appearance of the tree.

Immature crapemyrtle bark scale are hard to see with the naked eye, but adult scale covers and egg sacs are frequently visible on the upper branches and trunk of the tree. These scales include larger, white, oval (female) and smaller, elongate (male) scales.  Both male and female scales of the crapemyrtle bark scale are immobile, and will “bleed” pink blood when crushed.

Heavy crapemyrtle bark scale infestation

Heavy infestation of crapemyrtle bark scale with sooty mold. Presence of ladybeetle pupa indicates some predation. Photo by Erfan Vafaie.

Origin and Distribution

The crapemyrtle bark scale is native to Asia, and had previously been reported from China, Japan, and Korea. In its native range, it has been reported on plants from 16 different genera and 13 families, most notable persimmon and pomegranate.

Since its introduction, crapemyrtle bark scale has spread across most of the southeastern United States. Human transport on infested nursery material likely accounts for the long distance spread of the scale. Short distance spread likely occurs via wind or by hitchhiking on birds, mammals and larger flying insects.

Habitat & Hosts

Crapemyrtle bark scale is found almost exclusively on the bark. Within a tree, first stage crawler numbers are similar on both upper and lower branches, based on trapping on 12 trees in College Station TX throughout one season (Vafaie et al., 2015).

In the U.S., crapemyrtle bark scale has been seen primarily on crapemyrtle (Lagerstromia spp.), but also more recently confirmed on American beautyberry (Callicarpa americana.). Based on the literature from its native range (Wang et al. 2016a), crapemyrtle bark scale may be found on additional plant families. Although not yet confirmed, some additional plant hosts of crapemyrtle bark scale may include:
(Click scientific name for distribution in the U.S.)

Life Cycle

After hatching, the scale emerging from the egg is called a crawler. This first life stage (1st instar) is mobile and is the only stage that can disperse (via wind or animal transport). Once settled on the tree, the crawler remains in the same spot for the remainder of its immature life. Nymphs actively feed and produce honeydew. Mature female adults form a waxy protective covering (ovisac), mate with a male scale, and begin laying eggs. Females lay between 114 to 320 eggs in their lifetime (Jiang et al. 1998) and die in the egg sac. Upon completing their immature lifecycle, males pupate within the adult scale cover, and emerge as a winged adult.

Lifecycle of crapemyrtle bark scale

Life cycle of Acanthococcus lagerstromiae: (a) egg; (b) nymph; (c) pupae covered with white sac; (c-1) prepupa; (c-2) pupa; (d) adult female; (e) adult male; and (f) ovisac containing the gravid adult female. Figure from Wang et al. (2016b).

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Monitoring

Effective management of crapemyrtle bark scale relies on good monitoring practices to ensure that pesticides are targeted towards vulnerable stages. Spraying contact insecticides on egg sacs or pupae may have very little efficacy. Applications should be timed to target crawlers or immature nymphs before coating themselves in the white wax. Crawler activity appears to peak between mid-April to beginning of May for several locations across Texas and Louisiana. To determine crawler activity at your location, consider using double-sided sticky tape traps around the branch of the tree. Remove and replace with a new piece of tape weekly, and check tapes for presence of crawlers (see images below). When numbers of crawlers start to increase, consider control measures below.

Biological Control

Several natural enemies have been found in the landscape to provide suppression of crapemyrtle bark scale. In a lady beetle exclusion trial (pesticide treatment for lady beetles), natural enemies were found to provide approximately 75% suppression of crapemyrtle bark scale (Merchant et al., unpublished data).  Care should be taken to preserve natural enemies where possible.

Chemical Control

Several pesticides have been investigated for efficacy against crapemyrtle bark scale, with most success from the following active ingredients:

  • Imidacloprid (as a drench)
  • Dinotefuran (as a drench or bark spray)
  • Pyriproxyfen (as a bark spray)
  • Buprofezin (as a bark spray)
  • Bifenthrin (variable results, as a bark spray)

Drench applications should be made very early in the season, at the time of bud break (around March in Texas), since these drench insecticides can take about 60 days to translocate into the plant to be effective against the scale. The bark spray applications should ideally be made when crawlers are out and exposed; typically near mid-April and beginning of May. Spraying female egg sacs and male pupae may not be effective. Insecticide applications will not remove white spots or sooty mold, but prevent future scale population growth. Crapemyrtle trees shed their bark, and if crapemyrtle bark scale has been effectively managed, no new white spots or sooty mold should form after bark shedding. Please note that crapemyrtle aphids, a common pest found on crapemyrtle leaves, can also be a source of honeydew and subsequent sooty mold.

Related Publications

Vafaie et al. (2018). Spread and management of Acanthococcus (=EriococcuslagerstroemiaeKuwana (Hemiptera: Eriococcidae) on crapemyrtle (Lagerstroemia spp.) in the USA. International IPM Symposium. Poster.

Gu, M. (2018). Alternative hosts of crapemyrtle bark scale. Texas A&M AgriLife Extension.

Miller et al. (2017). Crapemyrtle bark scale: a pretty plant, an invasive pest, and a plan to protect pollinators. Poster.

Vafaie et al. (2017). Bark and systemic insecticidal control of Acanthococcus (=Eriococcuslagerstromiae (crapemyrtle bark scale) on landscape crapemyrtles, 2016. Arthropod Management Tests, 42: tsx130.

Vafaie et al. (2015). Spread and management of Eriococcus lagerstromiae Kuwana (Hemiptera: Eriococcidae) on crapemyrtle. Entomological Society of America. Poster.

Gu et al. (2014). Crapemyrtle bark scale: A new exotic pest. Texas A&M AgriLife Extension.

Gu et al. Crapemyrtle Bark Scale National Research Team Website. StopCMBS.com

Citations

Jiang, N.; Xu, H. (1998) Observation on Eriococcus lagerstroemiae Kuwana. J. Anhui Agric. Univ., 25: 142–144. (In Chinese)

Merchant et al. (2014). Discover and spread of Eriococcus lagerstromiae Kuwana (Hemiptera: Eriococcidae), a new invasive pest of crape myrtle, Lagerstromia spp. Entomological Society of America. Poster.

Wang et al. (2016a). Crapemyrtle bark scale: a new threat for crapemyrtles, a popular landscape plant in the U.S. Insects, 7(4): 78.

Wang, Z.; Chen, Y.; Knox, G.W.; Diaz, R. (2016b). Crape Myrtle Bark Scale. Available online: http://www.lsuagcenter.com/ ~/media/system/7/8/d/1/78d165df43ac0d4767607d88dadfb841/pub3440bugbizcrapemyrtlebarkscale_final.pdf (accessed on 16 May 2016).

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Oleander aphid

Article author: Wizzie Brown

Common Name(s): Oleander Aphid

Pest Location

Landscape Ornamental

Description

Adults are yellow with black legs and cornicles, which are two paired appendages that come off the tip of the abdomen.  Adults may be winged or wingless. Nymphs, or immatures, look the same as adults but are wingless and smaller in size. There are no eggs since the aphids give birth to live young.

Aphids on leaf

Origin and Distribution

Thought to come from the Mediterranean area. Found in tropical and warm temperate regions of the world.

Habitat & Hosts

Milkweed plantOleander, milkweed, butterfly weed

Life Cycle

Incomplete life cycle: nymph- adult

 

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Aphids on leafMany oleander aphids are attacked by a parasitic wasp that lays its egg within the aphid.  When the wasp egg hatches, it feeds on the internal organs of the aphid. The wasp larva pupates within the aphid, and emerges as an adult by cutting a hole in the top of the aphid’s abdomen.  Aphids that have been parasitized are referred to as aphid mummies.

Treatments with high pressure water sprays or pesticides such as insecticidal soaps or horticultural oils.

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Green lacewing

Article author: Wizzie Brown

Common Name(s): green lacewing

Description

Eggs are laid singly or in small groups.  They are small, white, and laid on a long, thin stalk.  Eggs are usually laid near a food source. Larvae are brown in white and tapered on both ends of the body.  Larvae have sickle-like mandibles that they use to feed on prey. Pupae are non-moving and non-feeding.  They are egg shaped and light in color and are found on plants. Adults are about ¾ of an inch long and light green in color.  Their wings are similar in size and shape and contain many veins, cross-veins, and cells.

Origin and Distribution

Green lacewings occur throughout North America.

Habitat & Hosts

Larvae feed on aphids and other small, soft-bodied insects.  Adults feed on pollen, nectar, and honeydew, but some feed on insects.

Life Cycle

Complete life cycle: egg- larva- pupa- adult.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Beneficial insect.  No management needed.

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