Diadromus

Morphological characters distinguishing Diadromus species include features of the head capsule, antennae, and wing venation. D. pulchellus can be distinguished from the sympatric D. subtilicornis by specific morphological traits detailed in diagnostic keys for North American populations. Species identification typically requires examination of adult specimens under magnification, with particular attention to antennal segment proportions and facial sculpture.

Europe and North America. Specific localities include southern France (Antibes) for natural populations of D. pulchellus.

• Acrolepiopsis assectella - parasitoidleek moth, nymphal/pupal stage; primary host for D. pulchellus
• Plutella xylostella - parasitoiddiamondback moth, pupal stage; host for D. collaris and D. subtilicornis
• Cacoecimorpha pronubana - kairomone detectionfrass volatiles detected by D. pulchellus but not primary host

D. collaris completes immature development within a single host pupa in 11–12 days at 25°C and 50–80% relative humidity. The egg is hymenopteriform and anhydropic. Four larval instars occur: first instar with sclerotized rectangular chitinous head capsule and distinct mandibles; second instar with trapezium-shaped head capsule; third instar similar to second but larger; fourth instar with significantly increased sclerotization and dimensions. The pupa is exarate and lacks a cocoon.

Host-finding behavior is mediated by volatile kairomones, specifically dialkyl disulphides present in host larval frass. These compounds are produced through bacterial metabolism of sulfur amino acids in the host gut rather than by the plant or phytophage directly. D. pulchellus uses caterpillar silk threads to locate host pupae. Host exploitation behaviors including attack rates, host feeding, and oviposition decisions are plastic and influenced by parasitoid physiological state, energy reserves, and prior host deprivation.

Endoparasitoid of lepidopteran pupae, contributing to population regulation of herbivorous moth species. Some species harbor vertically transmitted ascoviruses (DpAV in D. pulchellus) that amplify in host tissues during wasp larval development, with cell lysis synchronous with egg hatching; this viral facilitation may enhance wasp developmental success.

Species in this genus are important biological control agents. D. pulchellus has been field-released in North America for leek moth control. D. collaris is a significant natural enemy of diamondback moth, a major pest of cruciferous vegetables worldwide, and has been evaluated as a candidate biological control agent.

• Diadromus subtilicornisSympatric in North America; distinguished from D. pulchellus by morphological characters detailed in diagnostic keys; native parasitoid of diamondback moth versus introduced D. pulchellus targeting leek moth
• Cotesia vestalisAlso an endoparasitoid of Plutella xylostella, but attacks larval stage rather than pupal stage; venom composition differs substantially based on transcriptomic analysis

• parasitoid
• biological control
• Ichneumonidae
• lepidopteran parasitoid
• pupal parasitoid
• host-finding
• kairomones
• ascovirus
• Diadromus pulchellus
• Diadromus collaris
• integrated pest management

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Biological and molecular features of the relationships between Diadromus pulchellus ascovirus, a parasitoid hymenopteran wasp (Diadromus pulchellus) and its lepidopteran host, Acrolepiopsis assectella.
• Manipulation of parasitoid state influences host exploitation by Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae)
• Diadromus pulchellusin North America: field release against leek moth and new characters to distinguish it fromDiadromus subtilicornis, a native diamondback moth parasitoid
• The host specificity of the candidate biological control agent Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae)
• Release and post-release monitoring ofDiadromus pulchellus, a pupal parasitoid of leek moth (Acrolepiopsis assectella)
• DNA insertions as a component of the evolution of unique satellite DNA families in two genera of parasitoid wasps: Diadromus and Eupelmus (Hymenoptera).
• Role of Caterpillar Silk Thread in Location of Host Pupae by the Parasitoid Diadromus pulchellus
• Effects of host age on the performance of >Diadromus collaris, a pupal parasitoid of >Plutella xylostella
• Phylogenetic position of the Diadromus pulchellus ascovirus DNA polymerase among viruses with large double-stranded DNA genomes
• Host age selection by the host-feeding pupal parasitoid Diadromus subtilicornis (Gravenhorst) (Hymenoptera: Ichneumonidae).
• Identification of leek-moth and diamondback-moth frass volatiles that stimulate parasitoid,Diadromus pulchellus
• Microorganisms are involved in the production of volatile kairomones affecting the host seeking behaviour of Diadromus pulchellus, a parasitoid of Acrolepiopsis assectella
• Morphology and Development of Immature Stage ofDiadromus collaris(Hymenoptera: Ichneumonidae), an Important Endoparasitoid ofPlutella xylostella(Lepidoptera: Plutellidae)
• Reproductive compatibility and variation in survival and sex ratio between two geographic populations of Diadromus collaris, a pupal parasitoid of the diamondback moth, Plutella xylostella
• Comparative transcriptome analysis of venom glands from Cotesia vestalis and Diadromus collaris, two endoparasitoids of the host Plutella xylostella