''Cylindrocopturus adspersus'', the sunflower stem weevil, is a species of true weevil in the beetle family
Curculionidae.
[ It is found in North America,][ where the larvae tunnel in the stems of wild and cultivated sunflower plants.
]
Description
The adult sunflower stem weevil is about long and a grayish-brown color with irregular whitish markings. The larva is creamy white with a brown head.
Ecology
The adults emerge from their over-wintering chamber in old sunflower stumps in May or June and feeds on sunflower leaves, doing no significant damage. When ready to breed, the female chews a hole in the base of a sunflower stem and inserts a single egg, protecting it with frass
Frass refers loosely to the more or less solid excreta of insects, and to certain other related matter.
Definition and etymology
''Frass'' is an informal term and accordingly it is variously used and variously defined. It is derived from the G ...
. The larva feeds inside the stem and when fully developed descends to the base of the plant and hollows out a chamber in the woody tissue. It is this excavation that weakens the stem.[
The main parasitoid of the larva of the sunflower stem weevil is '']Nealiolus curculionis
''Nealiolus curculionis'' is a species of parasitic wasp in the family Braconidae. It is a parasitoid of the sunflower stem weevil '' Cylindrocopturus adspersus'', and a number of other species of stem-boring weevils.
Description
''Nealiolus c ...
'', a braconid
The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analys ...
wasp. The female of this wasp lays an egg inside the first instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow o ...
larva of the sunflower stem weevil, and when that larva enters diapause
In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...
in the fall, in a chamber near the base of the plant, the wasp larva also goes into hibernation. Both larvae resume activity in the spring, and about twenty days later, the wasp larva exits the weevil larva, feeds on its carcase and pupates. The adult wasp emerges about ten days later, both insects having a single generation each year.[
]
Damage
The sunflower is an important oil-producing crop in North America, and is also native to the continent. By excavating through the woody tissues, the larvae of the sunflower stem weevil makes the crop more susceptible to lodging in strong winds before the crop is harvested.Macrophomina phaseolina
''Macrophomina phaseolina'' is a Botryosphaeriaceae plant pathogen fungus that causes damping off, seedling blight, collar rot, stem rot, charcoal rot, basal stem rot, and root rot on many plant species.
Hosts, symptoms, and signs
One of the ...
'', the stems may develop black streaking and the crop may be affected by a ''Fusarium solani
''Fusarium solani'' is a species complex of at least 26 closely related filamentous fungi in the division Ascomycota, family Nectriaceae. It is the anamorph of ''Nectria haematococca''. It is a common soil fungus and colonist of plant materials ...
'' collar rot.
References
Further reading
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{{Taxonbar, from=Q54961180
Curculionidae
Articles created by Qbugbot
Beetles described in 1876