Chrysomela confluens

(Rogers, 1856)

Chrysomela confluens is a leaf beetle in the Chrysomelidae. Research demonstrates that this exhibits dramatically elevated abundance in plant hybrid zones between cottonwood species (Populus), where staggered leaf phenologies create 'phenological sinks' that concentrate . The species depends on newly flushed leaves for optimal growth and , and its distribution is strongly tied to plant rather than host plant alone.

Chrysomela confluens by (c) Don Loarie, some rights reserved (CC BY). Used under a CC-BY license.

Chrysomela confluens by (c) Don Loarie, some rights reserved (CC BY), uploaded by Don Loarie. Used under a CC-BY license.

Chrysomela confluens by no rights reserved, uploaded by Scott Loarie. Used under a CC0 license.

Pronunciation

How to pronounce Chrysomela confluens: //ˌkraɪsoʊˈmiːlə ˌkɒnˈfluːɛns//

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

Identification

Chrysomela confluens belongs to the Chrysomela, which contains leaf-feeding beetles generally associated with Salicaceae (willows and poplars). Within this genus, C. confluens is distinguished by its strong association with Populus hybrid zones and its dependence on newly flushed foliage. Specific diagnostic morphological features distinguishing C. confluens from are not documented in available sources.

Images

Habitat

Associated with Populus (poplar/cottonwood) stands, particularly in natural hybrid zones between cottonwood where staggered leaf phenologies occur. The hybrid zone represents less than 3% of the cottonwood but harbors 94% of the C. confluens population.

Distribution

North America; recorded from British Columbia, Canada and presumably distributed more broadly across the range of its Populus plants.

Seasonality

Activity tied to leaf flush of Populus; early leaf flush in hybrid zones provides the first food source in spring, with staggered phenologies allowing extended availability of suitable foliage through the growing season.

Diet

Folivory on Populus (poplar/cottonwood) leaves; specifically dependent on newly flushed leaves for optimal growth and .

Host Associations

Populus - primary plantSpecifically associated with hybrid zones between cottonwood ; leaf flush is critical to suitability

Behavior

females exhibit -shifting within hybrid zones, moving to newly flushed Fremont cottonwood trees as foliage of sympatric hybrid and narrowleaf trees declines in quality. This behavioral plasticity can result in a 600% increase in compared to non-shifting females.

Ecological Role

Herbivore that contributes to elevated herbivory pressure in plant hybrid zones; the demonstrates how phenological sinks can concentrate herbivore and chronically maintain high herbivory rates. Movement from hybrid zones reduces , suggesting into adjacent pure zones is hindered.

Similar Taxa

Other Chrysomela species share association with Salicaceae, but C. confluens is specifically distinguished by its concentration in Populus hybrid zones and dependence on phenological sinks
Chrysomela aeneicollisAnother montane leaf beetle in the same studied for , but associated with Salix (willow) in the Sierra Nevada rather than Populus hybrid zones