22182606
not annotated - annotated - LINNAEUS only
Sunflower stem weevil and its larval parasitoids in native sunflowers: is parasitoid abundance and diversity greater in the u.s. Southwest?
Classical biological control programs often target a pest's region of origin as a likely source for new biological control agents. Here, we use this approach to search for biological control agents of the sunflower stem weevil (Cylindrocopturus adspersus LeConte), an economically important pest of commercial sunflower. We conducted surveys of weevil natural enemy diversity and abundance across a transect running from the northern Great Plains to the southwestern U.S. (the presumed area of endemism of annual sunflower species in the genus Helianthus). Accordingly, natural enemy diversity and abundance were expected to be greater in the southwestern U.S. C. adspersus and their larval parasitoids were collected from stems of four native sunflower species (Helianthus annuus, H. nuttallii, H. pauciflorus, and H. petiolaris) from 147 sites across eight states. Native H. annuus constituted the majority of the sunflower populations. Mean weevil densities were significantly higher in sunflower stalks that were larger in diameter. Mean weevil densities within sites did not differ across the range of longitudes and latitudes sampled. After accounting for the effects of stalk diameter and location, weevil densities did not differ among the four sunflower species nor did they differ as a function of elevation. C. adspersus in H. annuus and H. petiolaris were attacked by seven species of parasitoids. No parasitoids were found attacking C. adspersus in H. nuttallii or H. pauciflorus stalks. C. adspersus were twice as likely to be attacked by a parasitoid when feeding on H. petiolaris than H. annuus. Furthermore, the likelihood that C. adspersus would be parasitized decreased with increasing elevation and increasing stem diameters. All parasitoid species have been previously reported attacking C. adspersus larvae in cultivated sunflower. Species richness was less diverse in these collections than from previous studies of cultivated sunflower. Our findings suggest that the species of larval parasitoids attacking C. adspersus in native sunflowers have successfully made the transition to cultivated sunflower.
Ann file
T1 Species 905 922 Helianthus annuus
N1 Reference T1 Taxonomy:4232
T2 Species 924 936 H. nuttallii
N2 Reference T2 Taxonomy:73302
T3 Species 938 952 H. pauciflorus
N3 Reference T3 Taxonomy:382521
T4 Species 958 971 H. petiolaris
N4 Reference T4 Taxonomy:4234
T5 Species 1016 1025 H. annuus
N5 Reference T5 Taxonomy:4232
T6 Species 1477 1486 H. annuus
N6 Reference T6 Taxonomy:4232
T7 Species 1491 1504 H. petiolaris
N7 Reference T7 Taxonomy:4234
T8 Species 1604 1616 H. nuttallii
N8 Reference T8 Taxonomy:73302
T9 Species 1620 1634 H. pauciflorus
N9 Reference T9 Taxonomy:382521
T10 Species 1724 1737 H. petiolaris
N10 Reference T10 Taxonomy:4234
T11 Species 1743 1752 H. annuus
N11 Reference T11 Taxonomy:4232
T12 Species 347 368 sunflower stem weevil
T13 Species 370 396 Cylindrocopturus adspersus
T14 Species 803 815 C. adspersus
T15 Species 1461 1473 C. adspersus
T16 Species 1588 1600 C. adspersus
T17 Species 1643 1655 C. adspersus
T18 Species 1787 1799 C. adspersus
T19 Species 1951 1963 C. adspersus
T20 Species 2173 2185 C. adspersus
T21 Species 452 461 sunflower
N12 Reference T21 Taxonomy:4232 Helianthus annuus
T22 Species 1058 1067 sunflower
N13 Reference T22 Taxonomy:4232 Helianthus annuus
T23 Species 1132 1141 sunflower
N14 Reference T23 Taxonomy:4232 Helianthus annuus
T24 Species 59 69 sunflowers
N15 Reference T24 Taxonomy:4232 Helianthus annuus
T25 Species 655 664 sunflower
N16 Reference T25 Taxonomy:4232 Helianthus annuus
T26 Species 886 895 sunflower
N17 Reference T26 Taxonomy:4232 Helianthus annuus
T27 Species 1395 1404 sunflower
N18 Reference T27 Taxonomy:4232 Helianthus annuus
T28 Species 1985 1994 sunflower
N19 Reference T28 Taxonomy:4232 Helianthus annuus
T29 Species 2092 2101 sunflower
N20 Reference T29 Taxonomy:4232 Helianthus annuus
T30 Species 2196 2206 sunflowers
N21 Reference T30 Taxonomy:4232 Helianthus annuus
T31 Species 2259 2268 sunflower
N22 Reference T31 Taxonomy:4232 Helianthus annuus
T32 Species 0 21 Sunflower stem weevil