@article{oppenheim_gould_hopper_2012, title={THE GENETIC ARCHITECTURE OF A COMPLEX ECOLOGICAL TRAIT: HOST PLANT USE IN THE SPECIALIST MOTH, HELIOTHIS SUBFLEXA}, volume={66}, ISSN={["1558-5646"]}, DOI={10.1111/j.1558-5646.2012.01712.x}, abstractNote={We used genetic mapping to examine the genetic architecture of differences in host plant use between two species of noctuid moths, Heliothis subflexa, a specialist on Physalis spp., and its close relative, the broad generalist H. virescens. We introgressed H. subflexa chromosomes into the H. virescens background and analyzed 1462 backcross insects. The effects of H. subflexa‐origin chromosomes were small when measured as the percent variation explained in backcross populations (0.2–5%), but were larger when considered in relation to the interspecific difference explained (1.5–165%). Most significant chromosomes had effects on more than one trait, and their effects varied between years, sexes, and genetic backgrounds. Different chromosomes could produce similar phenotypes, suggesting that the same trait might be controlled by different chromosomes in different backcross populations. It appears that many loci of small effect contribute to the use of Physalis by H. subflexa. We hypothesize that behavioral changes may have paved the way for physiological adaptation to Physalis by the generalist ancestor of H. subflexa and H. virescens.}, number={11}, journal={EVOLUTION}, author={Oppenheim, Sara J. and Gould, Fred and Hopper, Keith R.}, year={2012}, month={Nov}, pages={3336–3351} }
 @article{oppenheim_gould_2002, title={Behavioral adaptations increase the value of enemy-free space for Heliothis subflexa, a specialist herbivore.}, volume={56}, DOI={10.1111/j.0014-3820.2002.tb01379.x}, abstractNote={Abstract We investigated the importance of specialized behaviors in the use of enemy‐free space by comparing the host‐use behavior of two closely related moths, Heliothis subflexa Guenee and H. virescens Fabricius. Heliothis subflexa is a specialist on plants in the genus Physalis, whereas H. virescens is an extreme generalist, feeding on plants in at least 14 families. Heliothis subflexa uses the inflated calyx surrounding Physalis fruits as enemy‐free space, and field rates of parasitism for H. subflexa on Physalis are much lower than for H. virescens on tobacco and cotton, common hosts found in the same habitat as Physalis. If Physalis' architecture were solely responsible for H. subflexa's low rates of parasitism on Physalis, we predicted thatH. virescens larvae experimentally induced to feed on Physalis would experience parasitism rates similar to those ofH. subflexa. We found, however, that specialized host‐use and host‐acceptance behaviors are integral to the use of enemy‐free space on Physalis and strongly augment the effects of the structural refuge. In laboratory assays, we found considerable differences between the larval behavior of the specialist, H. subflexa, and the generalist, H. virescens, and these contributed to H. subflexa's superior use of enemy‐free space on Physalis. We tested the importance of these behavioral differences in the field by comparing parasitism of H. virescens on Physalis, H. virescens on tobacco, and H. subflexa on Physalis by Cardiochiles nigriceps Vierick, a specialist braconid parasitoid. For H. virescens, a threefold decrease in parasitism occurred when feeding on Physalis (mean parasitism ± SEM = 13 ± 4%) rather than tobacco (43 ± 4%), a difference we attribute to the structural refuge provided by Physalis. However, parasitism ofH. virescens on Physalis was more than ten times as great as that of H. subflexa on Physalis (1 ± 4%), supporting the hypothesis that specialized behaviors have a substantial impact on use of Physalis as enemy‐free space. Behavioral adaptations may be central to the use of enemy‐free space by phytophagous insects and may act as an important selective force in the evolution of dietary specialization.}, number={4}, journal={Evolution}, author={Oppenheim, S. J. and Gould, Fred}, year={2002}, pages={679–689} }
 @article{oppenheim_gould_2002, title={Is attraction fatal? The effects of herbivore-induced plant volatiles on herbivore parasitism}, volume={83}, ISSN={["1939-9170"]}, DOI={10.2307/3072090}, abstractNote={We investigated the relationship between parasitoid attraction to herbivore-induced plant volatiles and larval parasitism rates of two closely related heliothine, noctuid moths. Heliothis subflexa Guenee is a specialist on plants in the genus Physalis, while Heliothis virescens Fabricius is an extreme generalist. In North America, these species serve as the only known hosts for the specialist parasitoid Cardiochiles nigriceps Vierick; oviposition into Helicoverpa zea, a non-host, does occur but results in lethal encapsulation of C. nigriceps' eggs. Heliothis virescens larvae are parasitised by C. nigriceps far more frequently than are H. subflexa larvae. Parasitoid attraction to volatiles emitted by tobacco in response to herbivory by H. virescens has previously been demonstrated. Using field experiments, we examined the possibility that pre-detection defenses against parasitoid attraction to herbivore-induced plant volatiles are responsible for H. subflexa's relatively low rates of parasitism by C. nigriceps. Herbivore-damaged plants were significantly more attractive to C. nigriceps than were larvae, larval frass, larval saliva, or damaged leaves alone. Plant species affected parasitoid attraction: tobacco was the most preferred plant species, followed by Physalis angulata, and then cotton. The parasitoid was also more attracted to host species (H. subflexa and H. virescens) than to the non-host species, H. zea. There was an interaction between plant species and herbivore species: each plant species was most attractive when infested by its typical herbivore (e.g., H. virescens on tobacco). We compared these data with those of a previously published experiment on field parasitism of H. virescens and H. subflexa, conducted at the same time and place. Our results indicate that differences in parasitoid attraction to herbivore-induced plant volatiles do not contribute to H. subflexa's relatively low parasitism rate. For the generalist, H. virescens, rates of attraction correspond with rates of parasitism; for the specialist, H. subflexa, they do not. Attraction to H. subflexa on P. angulata is greater than to H. virescens on P. angulata, yet parasitism of H. subflexa is much less than parasitism of H. virescens. These results indicate that pre-detection defenses are not responsible for H. subflexa's low parasitism on P. angulata.}, number={12}, journal={ECOLOGY}, author={Oppenheim, SJ and Gould, F}, year={2002}, month={Dec}, pages={3416–3425} }
 @article{oppenheim_2001, title={Alternative agriculture in Cuba}, volume={47}, ISBN={1046-2821}, number={4}, journal={American Entomologist (Lanham, Md.)}, author={Oppenheim, S.}, year={2001}, pages={216} }
 @article{bernays_oppenheim_chapman_kwon_gould_2000, title={Taste sensitivity of insect herbivores to deterrents is greater in specialists than in generalists: A behavioral test of the hypothesis with two closely related caterpillars}, volume={26}, ISSN={["1573-1561"]}, DOI={10.1023/A:1005430010314}, number={2}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={Bernays, EA and Oppenheim, S and Chapman, RF and Kwon, H and Gould, F}, year={2000}, month={Feb}, pages={547–563} }