Chrysodeixis includens

(Walker, 1858)

Soybean Looper Moth, Soybean Looper, Falso Medidor

Chrysodeixis includens, the soybean , is a significant agricultural pest in the . The derives its from its preferred (soybean, Glycine max) and the characteristic looping movement of its . to the Americas, it ranges from southern Canada through the United States to Central and South America, the Caribbean, and the Galápagos Islands. The species is migratory and has expanded its economic importance in recent decades, becoming established in Brazil and Argentina where it has developed to multiple .

Chrysodeixis includens P1130272a by
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Pronunciation

How to pronounce Chrysodeixis includens: /ˌkɹɪsəˈdeɪksɪs ɪnˈkluːdɛnz/

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

Identification

can be distinguished from the similar Rachiplusia nu (sunflower ) by pattern: C. includens has two separated spots on the , while R. nu has two joined kidney-shaped spots. of the two are morphologically similar but can be distinguished by shape (R. nu has a more triangular spinneret, C. includens more conical), though this requires dissection. In practice, R. nu larvae often appear darker with a smoky- cast compared to the bright -green of C. includens, and R. nu shows distinct of tiny black asperites on the thoracic not apparent in C. includens. C. includens larvae have three pairs of , distinguishing them from true inchworms () which have only two pairs.

Images

Habitat

Primarily agricultural , especially soybean fields. Also found in other cultivated areas supporting its broad range. The has been observed in alfalfa, flax, sunflower, and various vegetable systems.

Distribution

to the Americas. Found from southern Quebec and southern Ontario through the eastern and southern United States to Central America, South America, the Antilles, and the Galápagos Islands. Established occur throughout Brazil and northern Argentina, where it has become an increasingly important pest in recent years. The is known to be migratory.

Seasonality

are on from April to November depending on location. In temperate regions, multiple occur during the growing season. In subtropical and tropical regions, continuous breeding is possible.

Diet

Highly . feed on foliage of numerous across multiple . Primary include Glycine max (soybean), Phaseolus vulgaris (common bean), Gossypium hirsutum (cotton), Nicotiana tabacum (), Solanum lycopersicum (tomato), Brassica oleracea, Lactuca sativa (lettuce), Helianthus annuus (sunflower), Zea mays (maize), Medicago sativa (alfalfa), Arachis hypogaea (peanut), and many others. Young larvae typically feed on lower leaf surfaces between , creating "window pane" damage; older larvae consume entire tissues while avoiding veins, resulting in skeletonized foliage.

Host Associations

Glycine max - primary Preferred ; feed on foliage, causing significant
Phaseolus vulgaris - feed on foliage
Gossypium hirsutum - feed on foliage
Nicotiana tabacum - feed on foliage
Solanum lycopersicum - feed on foliage
Helianthus annuus - feed on foliage
Medicago sativa - feed on foliage

Life Cycle

are laid on leaf undersides, primarily in middle or upper . through five ; early instars have black capsules, second instars light , later instars lightly colored with distinct bristles. Larvae display characteristic looping movement due to reduced number (three pairs). occurs in soil or leaf litter. Multiple per year in favorable climates. Developmental rate varies with temperature, instar, and larval weight.

Behavior

exhibit characteristic looping due to having only three pairs of , arching the body to bring the rear prolegs forward to meet the thoracic legs. Young larvae feed on lower leaf between ; older larvae leaves by consuming tissue while avoiding vascular bundles. are and migratory. Females exhibit clear preferences for position based on growth stage.

Ecological Role

Significant agricultural pest causing and yield loss in soybean and other . Serves as for multiple including Trichogramma spp. ( parasitoids), Microplitis demolitor and Copidosoma floridanum (larval parasitoids), and Tetrastichus howardi (pupal parasitoid). Preyed upon by including Podisus maculiventris () and Tadarida brasiliensis (Mexican free-tailed bat). influenced by under moist conditions.

Human Relevance

Major economic pest of soybean in North and South America. Larval feeding causes and yield reduction; damage thresholds exceed approximately 15% foliage loss during reproductive stages. Has developed to most used for control, complicating management. Subject of research using (ChinNPV), nematodes (Steinernema carpocapsae), and . Bt-traited soybeans have been developed for management. Misidentification with similar (especially Rachiplusia nu) leads to control failures due to differing susceptibilities.

Similar Taxa

Rachiplusia nuLarval extremely similar; distinguished by joined versus separated spots; distinguished by shape and subtle coloration differences; differs in susceptibility and geographic distribution
Trichoplusia ni (cabbage looper)Larval similar with three pairs; distinguished by preferences and geographic patterns; C. includens has black true legs, different capsule coloration in early
Anticarsia gemmatalis (velvetbean caterpillar)Co-occurs in soybean; distinguished by having five pairs of (not looping), different (flattened spherical, pinkish with age), and different larval coloration and movement
Spodoptera spp. (armyworms)Co-occur in soybean; distinguished by four pairs of , presence of pinaculae with stout , and different capsule markings
Helicoverpa zea (soybean podworm)Co-occurs in soybean; distinguished by larger size, different (barrel-shaped, laid on multiple parts including pods), and pod-feeding in addition to foliage feeding