BIOLOGY AND BEHAVIOR OF PRAON PEQUODORUM VIERECK (HYMENOPTERA: APHIDIIDAE), A PARASITOID OF THE PEA APHID

FRANCIS JOSEPH CHOW, Fordham University

Abstract

This research focused on aspects of Praon pequodorum which were previously unstudied.^ Male P. pequodorum mate more than once, while females probably do not. Host feeding does not occur prior to oviposition. Under laboratory conditions, superparasitism is common. Normally, supernumerary larvae are killed by physical attack and only one adult wasp emerges from a parasitized pea aphid. The ovipositor shaft of the adult female consists of a median dorsal stylet and a pair of toothed lancets ventral to it. When retracted, it is enclosed in the paired ovipositor sheaths. No sensory structures are found on any of these parts.^ Eclosion of the egg in the aphid hemocoel occurs about 74 hours after deposition. The 1st instar larva is mandibulate and is further characterized by the presence of rows of posteriorly-directed spines on the last thoracic and the 1st to 9th abdominal segments, and a posteriorly-directed cauda and 2 ventrally-directed processes on the 10th abdominal segment. This stage lasts about 21 hours at 21.1(DEGREES)C.^ The 2nd instar larva is nonmandibulate and lasts about 21 hours. The 3rd instar also lacks mandibles. It lasts about 14 hours and shows the beginning of lateral folds along the abdominal segments.^ The mandibulate 4th instar larva develops internally within the living aphid (about 15 hours) and externally after leaving the mummy to spin its cocoon underneath it (45 hours). The skirt-like cocoon is made up of an outer portion surrounding an inner one found directly around the developing wasp.^ The pharate prepupal stage lasts about 20 hours after the voiding of the jet-black, oval meconial pellets. The pupal stage lasts about 100 hours. The adult wasp emerges after chewing a smooth-edged circular exit hole through the cocoon. The complete life cycle at 21.1(DEGREES)C requires about 13 days.^ The abnormal development of some P. pequodorum individuals entirely within a host aphid and aphid mummy, instead of normal pupation within an external cocoon, was studied. This phenomenon may be influenced by high temperature and/or humidity, although high temperatures may also result in greater mortality during the 4th larval instar and the young adult stage.^

Subject Area

Entomology

Recommended Citation

CHOW, FRANCIS JOSEPH, "BIOLOGY AND BEHAVIOR OF PRAON PEQUODORUM VIERECK (HYMENOPTERA: APHIDIIDAE), A PARASITOID OF THE PEA APHID" (1982). ETD Collection for Fordham University. AAI8219233.
http://fordham.bepress.com/dissertations/AAI8219233

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