Phytodietus

Gravenhorst, 1829

Species Guides

Phytodietus is a -rich of ichneumonid wasps in the Tryphoninae, distributed across all zoogeographical regions. Members are koinobiont ectoparasitoids of semi-concealed Lepidoptera larvae, with documented associations primarily to Tortricidae and Pyralidae. The genus was recently recorded from Thailand for the first time, expanding Oriental region documentation. Several species have been investigated for of agricultural pests.

Phytodietus flavifrons by the Smithsonian. Used under a CC0 license.

Pronunciation

How to pronounce Phytodietus: /faɪtəˈdaɪətəs/

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Habitat

Forest including mixed deciduous forest, moist evergreen montane forest, hill evergreen forest, and pine forest; recorded at elevations 455–2286 m in Thailand. Agricultural systems including sugar-beet fields in the Great Plains region of North America.

Distribution

across all zoogeographical regions. Confirmed records include: Thailand (new record), China, India, Japan, Myanmar, Russia, Taiwan, Philippines, Sri Lanka, Indonesia, North America, Denmark, Norway, Sweden.

Seasonality

Multivoltine with extended activity periods: P. longicauda recorded May–December; P. pitambari April–August; P. spinipes January–June and October. P. vulgaris produces multiple annually with facultative regulated by .

Diet

do not feed; larvae are obligate feeding on Lepidoptera larvae.

Host Associations

Argyrotaenia citrana - Tortricidae; primary of P. vulgaris
Homona coffearia - Tortricidae; tea Tortrix, of P. spinipes in Sri Lanka, Taiwan, India
Homona sp. - Tortricidae; of P. spinipes in Java
Loxostege sticticalis - Pyraustidae; sugar-beet pest, of P. pulcherrimus
Loxostege frustalis - potential Pyraustidae; investigated as target for introduction, not confirmed natural

Life Cycle

to development takes 24–31 days in P. vulgaris. Mature larval stage serves as the stage; diapause is facultative and regulated by . Multiple per year. Adult lifespan approximately 10 days. Sex ratio 1:1.

Behavior

Females exhibit -seeking including antennal drumming on leaf surfaces to locate concealed host larvae. have limited capability. Koinobiont ectoparasitoid lifestyle: larvae feed externally on hosts that continue developing for a period.

Ecological Role

agent of tortricid and pyralid pests, particularly in agricultural systems. Documented role in suppression of tea Tortrix (Homona coffearia) and sugar-beet pest Loxostege sticticalis.

Human Relevance

Investigated and utilized as agent for agricultural pest management. P. pulcherrimus studied in 1941 for potential introduction to South Africa to control Loxostege frustalis damaging Karroo bush, important sheep-fodder. P. spinipes contributes to control of tea Tortrix, a significant tea pest.