Impact of Larval Crowding on Survival of Rhinocyllus conicus (Coleoptera: Curculionidae)

1981 ◽  
Vol 10 (4) ◽  
pp. 472-473 ◽  
Author(s):  
Patrick F. Dowd ◽  
L. T. Kok
Keyword(s):  
Rhinocyllus Conicus ◽  
Larval Crowding

Interspecific competition between Rhinocyllus conicus and Urophora soistitialis L on nodding thistle in Canterbury

2005 ◽  
Vol 58 ◽  
pp. 140-147 ◽  
Author(s):  
M.R. McNeill ◽  
C.J. Fletcher
Keyword(s):  
Interspecific Competition ◽  
Insect Species ◽  
Carduus Nutans ◽  
Rhinocyllus Conicus ◽  
Microctonus Aethiopoides

Nodding thistle receptacle weevil Rhinocyllus conicus and gallfly Urophora solstitialis attack the capitula of nodding thistle Carduus nutans L Between 31 October and 15 December 2003 the phenology of both R conicus and U solstitialis was studied at a dryland site in Canterbury Adult R conicus were more numerous than U solstitialis on capitula throughout the experiment Larvae of R conicus were first found on 11 November (15 of capitula infested) and peaked on 2 December with 53 of capitula infested Only 3 of capitula were infested by U solstitialis Adult R conicus or U solstitialis emerged from 79 of the selected primary and secondary capitula The majority of infested capitula (81) contained only R conicus 2 contained only U solstitialis while 17 contained both insect species Parasitism of R conicus by the braconid parasitoid Microctonus aethiopoides was low and occurred when most weevil eggs had been laid

Dispersal ofRhinocyllus conicusfor Biocontrol of Musk Thistle

Weed Science ◽  
1976 ◽  
Vol 24 (1) ◽  
pp. 59-62 ◽  
Author(s):  
J. M. Hodgson ◽  
N. E. Rees
Keyword(s):  
Seed Production ◽  
Carduus Nutans ◽  
Rhinocyllus Conicus ◽  
Made In

A weevil [Rhinocyllus conicus(Froelich)] host specific toCarduus, Cirsium, Silybum, andOnopordum, was introduced into Gallatin County, Montana, for biocontrol of musk thistle (Carduus nutansL.). Releases were made in 1969, 1971, 1972, and 1973 on local musk thistle infestations. The insects became established and overwintered successfully. In 1974,R. conicuswas found over a 1,280-km2area of the county in seed heads of musk thistle. Weevil larvae severely infected the primary flowers, but only a few secondary and later flowers were attacked. Seed production from infected primary flowers was greatly reduced, and other factors influenced reduction of seeds from secondary and later flowers.

scholarly journals Quantifying the Influence of Larval Density on Disease Transmission Indices in Culex quinquefasciatus, the Major African Vector of Filariasis

2019 ◽  
Vol 11 ◽  
pp. 117954331985602 ◽  
Author(s):  
Azubuike Christian Ukubuiwe ◽  
Chioma Cynthia Ojianwuna ◽  
Israel Kayode Olayemi ◽  
Francis Ofurum Arimoro ◽  
Innocent Chukwuemeka James Omalu ◽  
...  
Keyword(s):  
Culex Quinquefasciatus ◽  
Disease Transmission ◽  
Abiotic Factors ◽  
Larval Density ◽  
Field Trials ◽  
Negative Effects ◽  
Laboratory Findings ◽  
Factors Affecting ◽  
Adult Fitness ◽  
Larval Crowding

Larval crowding is one of the abiotic factors affecting biological fitness in mosquitoes. This study aims at elucidating, quantitatively, the influence of more larval crowding on aspects of fitness in Culex quinquefasciatus mosquito. To this end, day-old larvae of the species were reared in 4 density regimens equivalent to 1 larva in 1.25, 2.5, 5, and 10 mL of distilled water. Developmental indices, adult fitness indices, and accumulation and utilisation of teneral reserves for metamorphosis were determined at these density regimens. The results revealed varying significant negative effects of larval density on all fitness indices measured for the species. The study also revealed high utilisation of teneral reserves for metamorphosis at high larval densities. The information generated will be useful in making informed-decisions in allocating scare resources for vector control, although field trials are advocated to establish these laboratory findings.

Biological control of plumeless thistle (Carduus acanthoidesL.) in Argentina

Weed Science ◽  
1997 ◽  
Vol 45 (4) ◽  
pp. 534-537 ◽  
Author(s):  
Susana R. Feldman
Keyword(s):  
Biological Control ◽  
Oviposition Period ◽  
Adult Survival ◽  
Slight Tendency ◽  
Rhinocyllus Conicus

Plumeless thistle is a European Asteraceae naturalized in Argentina, where it is a troublesome pasture and range weed. A European weevil (Rhinocyllus conicus) was imported for biocontrol of this thistle. Oviposition patterns, egg to adult survival, and the weevil's effect on the production of achenes by thistles were monitored over 2 yr. The oviposition period did not begin simultaneously in all thistle populations, but finished in late November. Egg to larvae survival was 63% and egg to adult survival was approximately 50%. No important egg predators were detected. The weevils destroyed 80% of the propagules per capitulum and showed a slight tendency to adapt to the plumeless thistle cycle.

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