@article{unbehend_haenniger_vasquez_laura juarez_reisig_mcneil_meagher_jenkins_heckel_groot_2014, title={Geographic Variation in Sexual Attraction of Spodoptera frugiperda Corn- and Rice-Strain Males to Pheromone Lures}, volume={9}, ISSN={["1932-6203"]}, DOI={10.1371/journal.pone.0089255}, abstractNote={The corn- and rice-strains of Spodoptera frugiperda exhibit several genetic and behavioral differences and appear to be undergoing ecological speciation in sympatry. Previous studies reported conflicting results when investigating male attraction to pheromone lures in different regions, but this could have been due to inter-strain and/or geographic differences. Therefore, we investigated whether corn- and rice-strain males differed in their response to different synthetic pheromone blends in different regions in North America, the Caribbean and South America. All trapped males were strain-typed by two strain-specific mitochondrial DNA markers. In the first experiment, we found a nearly similar response of corn- and rice-strain males to two different 4-component blends, resembling the corn- and rice-strain female blend we previously described from females in Florida. This response showed some geographic variation in fields in Canada, North Carolina, Florida, Puerto Rico, and South America (Peru, Argentina). In dose-response experiments with the critical secondary sex pheromone component (Z)-7-dodecenyl acetate (Z7-12:OAc), we found some strain-specific differences in male attraction. While the response to Z7-12:OAc varied geographically in the corn-strain, rice-strain males showed almost no variation. We also found that the minor compound (Z)-11-hexadecenyl acetate (Z11-16:OAc) did not increase attraction of both strains in Florida and of corn-strain males in Peru. In a fourth experiment, where we added the stereo-isomer of the critical sex pheromone component, (E)-7-dodecenyl acetate, to the major pheromone component (Z)-9-tetradecenyl acetate (Z9-14:OAc), we found that this compound was attractive to males in North Carolina, but not to males in Peru. Overall, our results suggest that both strains show rather geographic than strain-specific differences in their response to pheromone lures, and that regional sexual communication differences might cause geographic differentiation between populations.}, number={2}, journal={PLOS ONE}, publisher={Public Library of Science (PLoS)}, author={Unbehend, Melanie and Haenniger, Sabine and Vasquez, Gissella M. and Laura Juarez, Maria and Reisig, Dominic and McNeil, Jeremy N. and Meagher, Robert L. and Jenkins, David A. and Heckel, David G. and Groot, Astrid T.}, editor={Newcomb, Richard DavidEditor}, year={2014}, month={Feb} }
 @article{vasquez_syed_estes_leal_gould_2013, title={Specificity of the receptor for the major sex pheromone component in Heliothis virescens}, volume={13}, DOI={10.1673/031.013.16001}, abstractNote={Abstract In a previous study, the Drosophila melanogaster OR67dGAL4;UAS system was used to functionally characterize the receptor for the major component of the sex pheromone in the tobacco budworm, Heliothis virescens Fabricius (Lepidoptera: Noctuidae), HvOR13. Electrophysiological and behavioral assays showed that transgenic flies expressing HvOR13 responded to (Z)-11-hexadecenal (Z11-16:Ald). However, tests were not performed to determine whether these flies would also respond to secondary components of the H. virescens sex pheromone. Thus, in this study the response spectrum of HvOR13 expressed in this system was examined by performing single cell recordings from odor receptor neuron in trichoid T1 sensilla on antennae of two Or67dGAL4 [1]; UAS-HvOR13 lines stimulated with Z11-16:Ald and six H. virescens secondary pheromone components. Fly courtship assays were also performed to examine the behavioral response of the Or67dGAL4[1]; UAS-HvOR13 flies to Z11-16:Ald and the secondary component Z9-14:Ald. Our combined electrophysiological and behavioral studies indicated high specificity and sensitivity of HvOR13 to Z11-16:Ald. Interestingly, a mutation leading to truncation in the HvOR13 C-terminal region affected but did not abolish pheromone receptor response to Z11-16:Ald. The findings are assessed in relationship to other HvOR13 heterologous expression studies, and the role of the C-terminal domain in receptor function is discussed. A third line expressing HvOR15 was also tested but did not respond to any of the seven pheromone components.}, journal={Journal of Insect Science (Tucson, AZ)}, author={Vasquez, G. M. and Syed, Z. and Estes, P. A. and Leal, W. S. and Gould, Fred}, year={2013} }
 @article{vasquez_vargo_silverman_2012, title={Fusion Between Southeastern United States Argentine Ant Colonies and Its Effect on Colony Size and Productivity}, volume={105}, ISSN={["1938-2901"]}, DOI={10.1603/an11114}, abstractNote={Abstract
               The ecological success of invasive ants has been linked to their ability to form expansive supercolonies. In the Argentine ant, Linepithema humile (Mayr), increased productivity and competitive ability of introduced supercolonies in several places, e.g., California and southern Europe, has been linked to high population densities that could have been attained via fusion of nonaggressive and genetically similar nests. Recently, we have found that introduced L. humile colonies in the southeastern United States, which have higher levels of intraspecific aggression and genetic diversity than those in California and southern Europe, sometimes also fuse; yet it is unclear what the longer term consequences of such colony fusion might be. In this study, we examined whether fusion of these southeastern United States L. humile colonies results in larger colonies by recording colony size and productivity in pairs that fused and in pairs that did not fuse. After 6 mo, colonies that fused produced 47% more workers and had twice as many queens as colony pairs that did not fuse. Also, fused colonies had an overall per capita colony productivity (number of brood and workers produced per queen and per worker) comparable to that of nonfused pairs and unpaired controls. Furthermore, all queens contributed to worker pupae production in fused colonies. Thus, fusion of initially aggressive southeastern United States L. humile colonies results in colonies with higher worker number without decreasing per capita productivity. Moreover, offspring contribution by all queens in fused colonies may alter colony genotypic composition resulting in reduced intraspecific aggression that in turn promotes further fusion. This process may be relevant to the establishment of incipient colonies in areas where multiple introductions have occurred.}, number={2}, journal={ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA}, author={Vasquez, Gissella M. and Vargo, Edward L. and Silverman, Jules}, year={2012}, month={Mar}, pages={268–274} }
 @article{vasquez_fischer_grozinger_gould_2011, title={Differential expression of odorant receptor genes involved in the sexual isolation of two Heliothis moths}, volume={20}, ISSN={["1365-2583"]}, DOI={10.1111/j.1365-2583.2010.01044.x}, abstractNote={AbstractMoth sexual communication systems are highly diverse, but the mechanisms underlying their evolutionary diversification remain unclear. Recently, genes coding for odorant receptors (ORs) OR6, OR14, OR15 and OR16 have been genetically associated with species‐specific male response to female pheromone blends in Heliothis virescens (Hv) and Heliothis subflexa (Hs). Quantitative real‐time PCR analysis indicates that expression of HvOR6, HsOR6, HvOR14, HsOR14, HvOR15 and HsOR15 is male biased, which supports the hypothesis that they have a role in mediating female sex pheromone detection. The genes HvOR14, HvOR15 and HvOR16 are expressed at higher levels than their corresponding orthologues HsOR14, HsOR15 and HsOR16 in male antennae, while HvOR6 and HsOR6 transcripts are equally abundant in male antennae. The lack of higher expression of any of the receptor genes in H. subflexa antennae suggests that interspecific sequence differences, rather than gene regulation differences, underly the species‐specific male response to pheromone components.}, number={1}, journal={INSECT MOLECULAR BIOLOGY}, author={Vasquez, G. M. and Fischer, P. and Grozinger, C. M. and Gould, F.}, year={2011}, month={Feb}, pages={115–124} }
 @article{vasquez_schal_silverman_2009, title={Colony Fusion in Argentine Ants is Guided by Worker and Queen Cuticular Hydrocarbon Profile Similarity}, volume={35}, ISSN={["1573-1561"]}, DOI={10.1007/s10886-009-9656-y}, abstractNote={Introduced populations of the Argentine ant, Linepithema humile, have experienced moderate to severe losses of genetic diversity, which may have affected nestmate recognition to various degrees. We hypothesized that cuticular hydrocarbons (CHC) serve as nestmate recognition cues, and facilitate colony fusion of unrelated L. humile colonies that share similar CHC profiles. In this study, we paired six southeastern U.S. L. humile colonies in a 6-month laboratory fusion assay, and determined if worker and queen CHC profile similarity between colonies was associated with colony fusion and intercolony genetic similarity. We also compared worker and queen CHC profiles between fused colony pairs and unpaired controls to determine if worker and queen chemical profiles changed after fusion. We found that colony fusion correlated with the CHC similarity of workers and queens, with the frequency of fusion increasing with greater CHC profile similarity between colonies. Worker and queen CHC profile similarity between colonies also was associated with genetic similarity between colonies. Queen CHC profiles in fused colonies appeared to be a mix of the two colony phenotypes. In contrast, when only one of the paired colonies survived, the CHC profile of the surviving queens did not diverge from that of the colony of origin. Similarly, workers in non-fused colonies maintained their colony-specific CHC, whereas in fused colonies the worker CHC profiles were intermediate between those of the two colonies. These results suggest a role for CHC in regulating interactions among mutually aggressive L. humile colonies, and demonstrate that colony fusion correlates with both genetic and CHC similarities. Further, changes in worker and queen chemical profiles in fused colonies suggest that CHC plasticity may sustain the cohesion of unrelated L. humile colonies that had fused.}, number={8}, journal={JOURNAL OF CHEMICAL ECOLOGY}, author={Vasquez, Gissella M. and Schal, Coby and Silverman, Jules}, year={2009}, month={Aug}, pages={922–932} }
 @article{vasquez_schal_silverman_2008, title={Cuticular hydrocarbons as queen adoption cues in the invasive Argentine ant}, volume={211}, ISSN={["1477-9145"]}, DOI={10.1242/jeb.017301}, abstractNote={SUMMARYIn social insects, individuals typically recognize and behave aggressively towards alien conspecifics, thereby maintaining colony integrity. This is presumably achieved via a nestmate recognition system in which cuticular compounds, usually cuticular hydrocarbons (CHC), of genetic and/or environmental origin serve as recognition cues. Most invasive populations of the Argentine ant, Linepithema humile (Mayr), display minimal nestmate–non-nestmate discrimination, resulting in low levels of intraspecific aggression allowing free movement of workers and queens among nests. However, invasive L. humile in the southeastern United States show relatively high levels of intraspecific aggression, and selectively adopt non-nestmate queens. Using behavioral assays and gas chromatography, we found an association between non-nestmate queen adoption and similarity of the CHC profiles of adopted and host colony queens. Also, nestmate and non-nestmate queen CHC profiles became more similar after adoption by queenless colonies. Furthermore, queens treated with non-nestmate queen CHC had distinct CHC profiles and were generally attacked by nestmate workers. We suggest that in L. humile, CHC are used as queen recognition cues, and that queen recognition errors are more likely to occur when the CHC profiles of non-nestmate and host colony queens are similar. Our findings provide further evidence for the complex and dynamic nature of L. humile nestmate discrimination, which may in part underlie the success of introduced populations of this invasive ant.}, number={8}, journal={JOURNAL OF EXPERIMENTAL BIOLOGY}, author={Vasquez, Gissella M. and Schal, Coby and Silverman, Jules}, year={2008}, month={Apr}, pages={1249–1256} }
 @article{vasquez_silverman_2008, title={Intraspecific aggression and colony fusion in the Argentine ant}, volume={75}, ISSN={["1095-8282"]}, DOI={10.1016/j.anbehav.2007.06.019}, abstractNote={Unicolonial ants possess an unusual social system characterized by the absence of internest aggression resulting in expansive networks where individuals move freely among distant nests. The Argentine ant, Linepithema humile (Mayr), can form geographically vast and numerically large unicolonial populations, or supercolonies, a trait that has been linked to its ecological success in the introduced range, and is one of the few invasive ants in which native and introduced populations have been examined to elucidate the origins and maintenance of unicoloniality. Supercolony formation may result from mixing of genetically homogenous and nonaggressive colonies, or initially aggressive colonies harbouring the most common recognition alleles. In this study, we examined interactions between mutually aggressive L. humile colonies in the absence of barriers limiting intercolony encounters to determine whether aggressive interactions result in either colony elimination or fusion into new nonaggressive colonies. By pairing experimental laboratory and field colonies displaying varying levels of intraspecific aggression, we determined that pairs that did not fuse had higher numbers of workers fighting and killed than colony pairs that fused and that genetic and cuticular hydrocarbon similarity between colony pairs was correlated with both levels of intraspecific aggression and colony fusion. We suggest that selective fusion of initially aggressive colonies sharing certain recognition cues may be a proximate mechanism shaping L. humile social structure, leading ultimately to extreme unicoloniality in introduced populations when ecological conditions are favourable.}, journal={ANIMAL BEHAVIOUR}, author={Vasquez, Gissella M. and Silverman, Jules}, year={2008}, month={Feb}, pages={583–593} }
 @article{vasquez_silverman_2008, title={Queen acceptance and the complexity of nestmate discrimination in the Argentine ant}, volume={62}, ISSN={["1432-0762"]}, DOI={10.1007/s00265-007-0478-z}, number={4}, journal={BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY}, author={Vasquez, Gissella M. and Silverman, Jules}, year={2008}, month={Feb}, pages={537–548} }
 @article{vasquez_orr_baker_2006, title={Efficacy assessment of Aphidius colemani (Hymenoptera : Braconidae) for suppression of Aphis gossypii (Homoptera : Aphididae) in greenhouse-grown chrysanthemum}, volume={99}, DOI={10.1603/0022-0493-99.4.1104}, abstractNote={Abstract To assess biological control as a management tool for the cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), the efficacy of Aphidius colemani Viereck (Hymenoptera: Braconidae) for suppression of A. gossypii in greenhouse-grown chrysanthemums, Dendranthema grandiflora (Tzvelev), was compared with a pesticide standard, imidacloprid (Marathon 1% G) and an untreated check. No significant differences were found between aphid populations in the two treatments. A. colemani and imidacloprid kept aphid numbers very low, with the correspondent aphid populations exhibiting very low intrinsic rates of increase (rm = −0.0369 and rm = 0.0151, respectively), in contrast to the exponential growth of aphid populations (rm = 0.1085) observed on the untreated plants. Parasitism levels in A. colemani plots ranged from 48.93 to 83.38%. Esthetic damage parameters, including exuviae, honeydew, and sooty mold on leaves, were significantly different between treatments and untreated control, and damage levels were minimal with the insecticide treatment and natural enemy releases. The cost of A. colemani releases was 4.7 times greater than the cost of the imidacloprid treatment.}, number={4}, journal={Journal of Economic Entomology}, author={Vasquez, G. M. and Orr, D. B. and Baker, J. R.}, year={2006}, pages={1104–1111} }