Caliothrips

Daniel, 1904

bean thrips, banded thrips

Caliothrips is a of in the , Panchaetothripinae, established by Daniel in 1904. in this genus are , typically associated with leaves, and several are recognized as agricultural pests. The genus includes notable species such as C. phaseoli (bean thrips) and C. fasciatus (North bean thrips), which feed on legumes and other . are characterized by distinct banding patterns and small size (~1 mm). Some species have been intercepted in international trade, particularly in navel oranges, triggering concerns.

Caliothrips by no rights reserved, uploaded by Jesse Rorabaugh. Used under a CC0 license.

Pronunciation

How to pronounce Caliothrips: //kæliˈoʊθrɪps//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Members of Caliothrips can be distinguished from the superficially similar predatory Aeolothrips ( ) by banding patterns and family-level characters. In C. phaseoli, the display and post- on a dark background, whereas Aeolothrips fasciatus shows humeral, median, and white bands. Caliothrips possess the single characteristic of , used for rasping tissue. The genus is placed in Panchaetothripinae based on antennal and features. Species-level identification requires examination of subtle differences in abdominal sculpturing and wing pattern details.

Images

Habitat

are associated with leaves of plants, particularly in agricultural and natural vegetation settings. In systems, they occupy the lower, protected leaf surfaces of plants such as soybean, beans, onion, and various legumes. The has been recorded from and crops, urban ornamentals, and flora.

Distribution

The occurs in the Americas, with records from North America (USA, California; Mexico), Central America (Panama), and South America (Argentina, Brazil). C. fasciatus is to western North America. C. phaseoli is widespread in North, Central, and South America. Some have been proposed as distinct (e.g., C. brasiliensis for South populations of C. phaseoli). Despite regular interception in exported navel oranges, established populations have not been detected outside the Americas.

Diet

; feeds on tissues through rasping-. Documented include legumes (Fabaceae: soybean, beans), onion (Allium cepa, Amaryllidaceae), Solanum dulcamara (Solanaceae), cotton, , and various economic plants. Feeding causes lacerations, spots, and leaf drying.

Host Associations

Glycine max - pest ofsoybean, major in Argentina
Allium cepa - pest ofonion, first record in Panama 2020-2021
Phaseolus vulgaris - pest ofcommon bean
Solanum dulcamara - bittersweet nightshade
Gossypium - pest ofcotton
Fragaria - pest of

Life Cycle

Development includes , two larval , , , and stages—a pattern intermediate between incomplete and . First- and second-instar feed actively; third- and fourth-instars (propupa and pupa) are quiescent, non-feeding stages. Under laboratory conditions, development from egg to adult is temperature-dependent, with thermal thresholds estimated at ~0-6.5°C, optimum ~31-32.5°C, and maximum ~35-38°C. accumulation for complete development approximately 370-385. In field in Panama, stages comprised 46% of captured specimens, indicating active on plants.

Behavior

aggregate in protected locations on plants, particularly lower leaf surfaces. In C. phaseoli, specific sensitivity to ultraviolet-B radiation (290-330 nm) has been demonstrated; the contains a fluorescent internal filter in most that blocks longer UV wavelengths, enabling specialized UV-B . Adults of C. fasciatus overwinter in the navels of navel oranges, facilitating accidental transport in international trade. Virgin females of C. fasciatus do not produce offspring when isolated individually, but will produce sons in the presence of other virgin females.

Ecological Role

Primary consumers of tissues; function as agricultural pests causing direct feeding damage and, through , additional plant injury. In , they serve as for predatory including (e.g., Eriopis connexa in Argentine soybean fields). surges have been associated with dry conditions. The contributes to background diversity in agricultural and natural systems, with survey work in Australia documenting related but failing to find established C. fasciatus populations.

Human Relevance

Several are economically significant agricultural pests. C. phaseoli is a pest of soybean in South America and has been recently recorded damaging onion in Panama. C. fasciatus is a for countries importing California navel oranges due to in fruit navels; this has necessitated and cold protocols. Control is problematic due to short times (approximately 2 weeks from to egg), preference for protected feeding locations, and limited registered for some . The has been subject to extensive survey and efforts to prevent establishment.

Similar Taxa

AeolothripsPredatory in with similar black-and- banded patterns; distinguished by family-level characters (antennal structure, number), wing banding details, and predatory versus habits
FrankliniellaAnother in with some banded ; distinguished by abdominal and pattern details, and by ecological associations
Echinothrips americanusPoinsettia with banding; distinguished by having a distinct white only at the wing base versus the and post- bands of Caliothrips

More Details

Taxonomic uncertainty

There is disagreement regarding boundaries within Caliothrips. Some authorities recognize South of C. phaseoli as distinct species C. brasiliensis (or C. braziliensis) based on solid dark versus medially lightened elytral . C. phaseoli has also been treated as a synonym of C. fasciatus in some literature, though morphological differences in abdominal sculpturing have been noted. C. marginipennis has been synonymized with C. punctipennis, and C. fasciatus was withdrawn from the Brazilian fauna list.

Invasion biology

Despite more than 120 years of regular interception in exported navel oranges and substantial pressure, C. fasciatus has failed to establish outside North America. The cold accumulation hypothesis suggests that low temperatures during transit (2.78°C for 18-24 days) cause high mortality and compromised in survivors. Genetic studies reveal phylogeographic structure within C. fasciatus, with potentially two cryptic (forms A and B) and outbreeding depression between geographically isolated .

Sensory biology

C. phaseoli possesses a specialized visual system for detecting solar UV-B radiation, achieved through a standard UV-A photoreceptor combined with a sharp cut-off internal filter in the . This is rare among and represents an for detecting a narrow, low-abundance portion of the solar spectrum.