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Two diterpenoid alcohols, ent-kauran-16alpha-ol (1) and ent-atisan-16alpha-ol (2), were isolated from pre bloom (R3-R4 stage) sunflower heads as oviposition stimulants for the banded sunflower moth, Cochylis hospes. Fractionation of a sunflower head extract, by normal-phase flash column chromatography, resulted in an early eluting fraction exhibiting significant activity in an egg-laying bioassay. Compounds 1 and 2, along with ent-trachyloban-19-oic acid (3) and ent-kaur-16-en-19-oic acid (4), were isolated as the major components of this fraction and identified by their NMR and mass spectra. The purified compounds were individually tested for ovipositional activity in dose-response bioassays. In these bioassays, compounds 1 and 2 gave linear dose responses, with increasing numbers of eggs laid as the dosage of either increased. Compounds 3 and 4 failed to stimulate significant egglaying at any of the dosages tested. A factorial design bioassay, using compounds 1 and 2, showed that 1 was relatively more stimulatory than 2, and that there was no synergistic effect on oviposition when the two compounds were combined.

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The sunflower stem weevil, Cylindrocopturus adspersus (LeConte), is a pest of cultivated sunflower in the major production areas of North and South Dakota, Minnesota, and Texas. Adults appeared in sunflower plots between 5 and 25 June in 1980–1985, when plants had 4–14 leaves. Oviposition began soon after adults were present and continued into late August. Peak densities of both eggs and adults occurred in mid-July. Larvae hatched between 6 and 11 July, when plants were in the early flower bud growth stages. Larvae fed in the sunflower stalk and moved to the stalk base or root crown to construct overwintering chambers. The seasonal patterns of the weevil’s life stages in 6 years were similar, but population densities varied. Regression equations were developed to predict larval numbers in stalks from number of adults to aid in making control decisions.

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Tbe banded sunOower moth (Cochylis hospes Walsingbam; Lepidoptera: Cocbylidae) is a pest of sunOower (Helianthus annuus L.) in tbo: northern Great Plains. Larvae feed Initially on sunnower Oorets and subsequently on immature and matue seeds (acbenes). Our objedlve was to measure tbe compensatory ability of sunOower for increasing seed yield In response to tbe loss of Oorets caused by Ooret and seed feeding of tbe banded sunOower moth for tbe accurate computation of economic Injury levels. Treatments were removal of Ooret at 10o/c Increment intervals from 0 to SOo/c of tbe Oorets of sunOower beads (capitula) at Dowering. Floret removal bad a direct effect on tbe number of resulting fertile seeds. Reducing tbe number of Oorets by 10% resulted in a 20o/c decrease in tbe number of fertile seed, an 18% decrease In total seed weight of tbe bead, and a 22% decrease in seed volume. Comparable decreases were found in tbe number of fertile seeds for other increments of Ooret removal. Tbe sunnower plant can compensate for Ooret removal by increasing tbe weight of individual seeds. As percent of Ooret loss increased, seed weight increased, but even when only 10o/c of tbe Oorets were destroyed, tbe weight gain did not overcome tbe subsequent loss of seeds. Oil content of seeds significantly decreased as Ooret loss increased. In addition to consumption of mature seeds, simulation of damage showed that early feeding by banded sunOower moth larvae on Oorets can also directly and indirectly affect tbe final yield of infested plants.

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