Establishment in Missouri ofRhinocyllus conicusfor the Biological Control of Musk Thistle(Carduus nutans)

A weevil,(Rhinocyllus conicusFroelich) was introduced into Missouri in 1975 to aid in reducing populations of musk thistle,(Carduus nutansL.). The weevil was recovered in 1976 from as far as 3.2 km from the release site and 4.8 km in 1977. Infestation levels of flower heads at the release site ranged from 46 to 90%. Native parasites(Bracon mellitorSay) and [Aliolus curculionis(Fitch)] were reared from weevil larvae.

A TEMPERATURE-DRIVEN DEVELOPMENTAL MODEL FOR THE PARASITE BRACON MELLITOR (HYMENOPTERA: BRACONIDAE),

The influence of temperature on the development of immature stages of Bracon mellitor Say, a braconid parasite of the boll weevil, Anthonomus grandis Boheman, was studied at a series of constant and variable temperatures. Resulting developmental rates and times were compatible with recent advances in the theory of thermal responses exhibited by poikilotherms. Mean development times recorded were in close agreement with predictions calculated from a previously derived absolute reaction rate development model.Bracon mellitor cohort developmental data were also checked against a prototype stochastic cohort development model. In this comparison, observed and predicted probability distributions agreed for constant and variable day/night temperature regimes but showed some differences under sinusoidal temperature regimes.