Epilachninae

leaf-feeding lady beetles, phytophagous lady beetles

Epilachninae is a of () distinguished from other coccinellids by their herbivorous diet. superficially resemble predatory lady beetles but feed exclusively on material, making several significant agricultural pests. The subfamily comprises approximately 16% of described Coccinellidae species. are covered with of spiny projections, unlike the smooth larvae of predatory coccinellids. Many species are or narrowly , feeding on specific plants within Solanaceae, Cucurbitaceae, and other . Some species, particularly in the Henosepilachna, have been to new regions where they have become pests of solanaceous .

Epilachna borealis by (c) skitterbug, some rights reserved (CC BY), uploaded by skitterbug. Used under a CC-BY license.

HL1 1389 by Raffaelepilia.. Used under a CC BY-SA 4.0 license.

Subcoccinella vigintiquatuorpunctata (53133338725) by Gilles San Martin from Namur, Belgium. Used under a CC BY-SA 2.0 license.

Pronunciation

How to pronounce Epilachninae: /ˌɛpɪˈlæknɪniː/

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Identification

resemble other in general body form but can be difficult to identify to based on external markings alone, as elytral patterns vary considerably within species and may be nearly identical between unrelated species. Reliable identification requires examination of male or study of and , which are often more distinctive than adults. Eggs are , two to three times longer than wide, standing in batches on leaf surfaces; microscopically they differ from most other eggs in having a definite reticular pattern of sculpting on the rather than a smooth surface. Larvae are distinguished by of spiny projections covering the body, in contrast to the smooth or only lightly larvae of predatory Coccinellidae.

Images

Habitat

Occurs in diverse where plants grow, including agricultural fields, gardens, and natural vegetation. show adaptability to different regions and climates where their host plants occur.

Distribution

Worldwide distribution with ranges in Asia, Africa, and the Americas; several have been to new regions. Henosepilachna vigintioctopunctata, native to India and southeastern Asia, has established in South America including Brazil and Argentina. The is taxonomically most diverse in the tropics and subtropics.

Seasonality

Activity patterns vary by and region. Many species have one or two per year. Some or species migrate to high points on ridges or peaks to hibernate or aestivate in masses. In central-western Mexico, Epilachna difficilis occurs from mid-August to early December.

Diet

Exclusively herbivorous; and feed on leaves. Most are or narrowly . Adults typically feed on the upper surface of leaves, while larvae feed on the lower surface. Feeding involves scraping one of the leaf, leaving larger and the far face largely intact. plants include species in Solanaceae (eggplant, tomato, potato, , nightshades), Cucurbitaceae (cucumber, squash, melons), Amaranthaceae, Brassicaceae, Fabaceae (beans, soybean), Malvaceae (cotton), and other . Some species feed on maize and spinach.

Host Associations

Solanum melongena - eggplant
Solanum lycopersicum - tomato
Solanum tuberosum - potato
Nicotiana tabacum -
Physalis angulata -
Cucumis sativus - cucumber
Cucurbita - squash
Glycine max - soybean
Phaseolus vulgaris - common bean
Zea mays - maize
Spinacia oleracea - spinach
Gossypium - cotton
Brassica -
Bonplandia geminiflora - Polemoniaceae

Life Cycle

are laid in batches of a few dozen on leaf surfaces; a single female may lay a few hundred eggs. through five over four to five weeks. Larvae anchor themselves to a protected spot on the to pupate. The pupal stage lasts several days. Complete from egg to takes approximately 37-38 days under laboratory conditions for some . Many species have one or two per year.

Behavior

and feed gregariously on leaves. Adults between host plants. Some migrate tens of kilometers to high points on ridges or peaks to hibernate or aestivate in masses. Males of some species show unilateral mate choice, preferring females. Females of some species show fastidiousness at mating, rejecting heterospecific males. Feeding produces characteristic damage marks on leaves; for example, maize-feeding species produce long streaks parallel to leaf , while Solanaceae-feeding species leave arcs of skeletonized leaf.

Ecological Role

that can cause significant of plants, with damage ranging from 38% to over 98% of leaf area in some cases. Serve as for various including that attack or , and predatory and that attack larvae. Some have been investigated as potential agents for pest thistles.

Human Relevance

Several are significant agricultural pests causing locally serious , particularly in Solanaceae and Cucurbitaceae . Notable include the () and squash (Epilachna borealis) in North America, and the 28-spotted (Henosepilachna vigintioctopunctata) which has become in South America. Control strategies must consider that often kill and that may respond poorly to ; approaches are recommended. Some species are considered as potential of pest weeds such as thistles.

Similar Taxa

CoccinellinaeOther containing predatory ; superficially similar in appearance but differ in biology and larval . Coccinellinae are smooth or lightly , not covered with spiny projections. Epilachninae can be distinguished by herbivorous mouthparts and feeding damage on plants.
Chrysomelidae containing many herbivorous that feed on similar plants and may be confused in the field. Epilachninae can be distinguished by the typical body form, with clubbed tips, and larval with spiny projections.

More Details

Taxonomic instability

The of Epilachninae is constantly in flux. While recent support their status as a , some authors treat them as a tribe or series of tribes within Coccinellinae. The number of recognized tribes varies, though four tribes is the most commonly accepted system. The Epilachna has been split based on more reliable morphological characters including , with over a dozen new genera described or elevated from subgeneric rank in the tribe Epilachnini alone. The position of Subcoccinella within the subfamily remains questionable.

Reproductive anatomy

Recent research has revealed a novel sperm organ in Epilachninae that differs from the typical , representing a significant evolutionary modification in this .