Ovary development of Larinus minutus Gyllenhal (Coleoptera: Curculionidae)

Introduced and established in the 1990’s to the United States, Larinus minutus has become one of a cadre of biological control agents brought to North America to control knapweeds (Centaurea spp.). This weevil was introduced and established in the northwestern portion of Arkansas with the intention of reducing knapweed densities and further range expansion southward.  Adult weevils and spotted knapweed occur earlier and persist later than in northern states, and the ability of the weevil to begin egg production is thought to be dependent upon phytophagy of flowers and pollen of spotted knapweed. The majority of knapweed in Arkansas is found along roadsides and is mowed around peak flowering which could inhibit adult weevils’ ability to produce eggs if it occurs prior to flowering. We collected female L. minutus and placed them on individual flowers using mesh bags. Weevils were divided into a control group with access to flowers for the duration of the experiment and the treatment that is artificially ‘mowed’ prior to flowering. Weevils were collected randomly from each treatment every week and dissected to determine effect of treatment on ovaries, egg production and presence/absence of follicular relics. We hypothesize that the weevils in the treatment group will not develop mature ovaries.