Showing papers by "Jocelyn G. Millar published in 2004"

Advances in insect chemical ecology

Abstract: Preface 1. Phytochemical diversity of insect defenses in tropical and temperate plant families John T. Arason, Gabriel Guillet and Tony Durst 2. Recruitment of predators and parasitoids by herbivore-injured plants Ted C. J. Turlings and Felix Wackers 3. Chemical ecology of astigmatid mites Yasumasa Kuwahara 4. Semiochemistry of spiders Stefan Schulz 5. Why do flowers smell? The chemical ecology of fragrance-driven pollination Robert A. Raguso 6. Sex pheromones of cockroaches Cesar Gemeno and Coby Schal 7. A quest for alkaloids: curious relationship between tiger moths and plants containing pyrrolizidine alkaloids William E. Conner and Susan J. Weller 8. Structure of the pheromone communication channel in moths Ring T. Carde and Kenneth F. Haynes Index.

Identification of volatile synomones, induced by Nezara viridula feeding and oviposition on bean spp., that attract the egg parasitoid Trissolcus basalis

Abstract: Bean plants (Vicia faba L. and Phaseolus vulgaris L.) damaged by feeding activity of Nezara viridula (L.) (Heteroptera: Pentatomidae), and onto which an egg mass had been laid, produced volatiles that attracted the egg parasitoid Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae). Extracts of volatiles of broad bean and French bean plants induced by adults of N. viridula as a result of their feeding activity, oviposition activity, and feeding and oviposition activity combined were analyzed by gas chromatography-mass spectrometry (GC-MS), and tested in Y-tube olfactometer bioassays as attractants for T. basalis females. In extracts from undamaged leguminous plants, green-leaf volatiles were absent or scarcely detected, and monoterpenes and sesquiterpenes were present at trace levels. No significant differences were detected in the profiles of volatiles of undamaged plants, and undamaged plants on which bugs were allowed only to lay eggs. In contrast, feeding and oviposition by adults of N. viridula induced in both leguminous plants a significant increase in terpenoids such as linalool, (E)-beta-caryophyllene, (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene, and (3E)-4,8-dimethyl-1,3,7-nonatriene, which was induced only in French bean plants. Quantitative comparisons revealed increased levels of (E)-beta-caryophyllene in extracts from feeding-damaged plants with N. viridula egg masses compared to feeding-damaged plants without egg masses. In Y-tube olfactometer bioassays, T. basalis females were attracted by extracts of both leguminous plants only when N. viridula adults were allowed to feed and oviposit upon them. Fractionation of extracts of volatiles from broad bean plants with N. viridula feeding damage and egg masses yielded two fractions. but only the fraction containing (E)-beta-caryophyllene was attractive to the egg parasitoid. These findings indicate that N. viridula feeding and oviposition induce leguminous plants to produce blends of volatiles that are characterized by increased amounts of (E)-beta-caryophyllene, and these blends attract female T. basalis. The role of (E)-beta-caryophyllene as a potential synomone for T. basalis is discussed.

Male-Produced Aggregation Pheromone of the Cerambycid Beetle Neoclytus acuminatus acuminatus

Abstract: This is the first fully verified report of an aggregation pheromone produced by a cerambycid beetle species. Field bioassays with adultNeoclytus acuminatus acuminatus (F.) (Coleoptera: Cerambycidae) revealed that males produce a pheromone that attracts both sexes. Extracts of odors from males contained a single major male-specific compound, (2S,3S)-hexanediol. Field trials determined that both sexes were attracted by the racemic blend of (2S,3S)- and (2R,3R)-hexanediols and that activity was similar to enantiomerically enriched (2S,3S)-hexanediol (e.e. 80.2%). However, the blend of all four 2,3-hexanediol stereoisomers attracted few beetles, indicating inhibition by one or both of the (2R*,3S*)-stereoisomers. Females of the cerambycidCurius dentatus Newman were attracted to traps baited with the four component blend, suggesting that a male-produced sex pheromone for this species may contain (2R,3S)-hexanediol and/or (2S,3R)-hexanediol. The pheromone ofN. a. acuminatus, and presumed pheromone ofC. dentatus, bear structural similarities to those produced by males of six other species in the Cerambycinae (straight chains of 6, 8, or 10 carbons with hydroxyl or carbonyl groups at C2 and C3). It is likely that males of other species in this large subfamily produce pheromones that are variations on this structural motif.

Vibratory signals of the harlequin bug and their transmission through plants

Abstract: . Males of the harlequin bug, Murgantia histrionica (Hahn), produce five different vibrational songs, whereas females produce one song. Songs differ from those of other stink bugs primarily in their species-specific temporal characteristics. The broad band male courtship songs of M. histrionica are achieved by a combination of different frequency modulated and/or narrow band subunits, with several higher harmonic frequencies. Males rather than females initiate substrate-borne vibrational communication, and the longer-range calling songs found typically in other pentatomid species are lacking. Interindividual differences in song temporal and spectral characteristics are discussed. Transmission of vibrational songs through a cabbage head is more efficient along veins than along lamina. Attenuation of signals transmitted through veins is low and similar to that reported previously for plant stalks. On the leaf vein, distances between peak amplitude minima and maxima are different for the dominant and subdominant frequencies. At any distance from the vibration source, a different relationship between spectral peak amplitudes can be recorded. Resolution of these differences, together with velocity differences between signals recorded on the vein and lamina, may help small stink bugs to estimate distance and to locate each other on a plant.

Chemical and physical signals mediating conspecific and heterospecific aggregation behavior of first instar stink bugs

Abstract: We investigated cues that mediate the aggregation behavior of immature pentatomid bugs by using nymphs of six different pentatomid bug species (Nezara viridula, Acrosternum hilare, Chlorochroa ligata, Chlorochroa sayi, Thyanta pallidovirens, and Euschistus conspersus) When first instars of any two species were put together in a Petri dish, they readily formed heterospecific aggregations similar to their natural conspecific aggregations The chemical profiles of first and second instar nymphs of each species were determined by solvent extraction with pentane, followed by GC–MS analysis Immature bugs of the different species had some compounds in common, and some that were more species specific Within a species, there were distinct differences in the profiles of compounds extracted from first and second instars Bugs did not aggregate around untreated polysulfone beads (1 mm diam) that were glued together in groups approximating bug egg masses, suggesting that tactile cues alone were insufficient to induce aggregation Furthermore, when tested over a range of doses, groups of polysulfone beads treated with crude whole-body extracts of bugs did not induce or maintain aggregations However, first instar N viridula nymphs did respond to beads treated with two of the three major components of bug extracts 4-Oxo-(E)-2-decenal induced significant aggregations at two doses, whereas tridecane, the major component in extracts from all six species, did not, and (E)-2-decenal was repellent The repellence of (E)-2-decenal may explain why we and previous researchers were unable to induce aggregations of first instar N viridula using whole-body extracts

Effects of Temperature on Fecundity and Longevity of Phoracantha recurva and P. semipunctata (Coleoptera: Cerambycidae)

Abstract: The cerambycid beetles Phoracantha recurva Newman and Phoracantha semipunctata F. were accidentally introduced into southern California where they have caused significant mortality to eucalyptus trees. In recent years, P. recurva populations have increased rapidly with a concomitant decrease in P. semipunctata numbers in their shared habitat in southern California. P. recurva has been collected in field surveys earlier in the season, suggesting that this species may be active over a broader range of temperatures and consequently have a longer seasonal activity period. We conducted lifetime fecundity studies to examine egg production, egg hatch, and adult longevity of beetles of both species subjected to temperatures typical of late fall and late winter/early spring in southern California. Overall, there were no differences in lifetime fecundity between P. recurva and P. semipunctata. P. recurva did not seem to reproduce over a larger range of temperatures than P. semipunctata, and there did not seem to be any substantial differences in their reproductive biologies. P. recurva eclosed slightly faster and lived slightly longer at reproductive temperatures than P. semipunctata, suggesting that P. recurva may have a slight reproductive advantage over P. semipunctata. However, it seems unlikely that such an advantage can account for the rapid increase in P. recurva populations and the simultaneous decrease in P. semipunctata populations in southern California.

Seasonal Development of Phoracantha recurva and P. semipunctata (Coleoptera: Cerambycidae) in Southern California

Abstract: A seasonal development study of the cerambycid beetles Phoracantha recurva Newman and Phoracantha semipunctata (Fabricius) (Coleoptera: Cerambycidae) was conducted under field conditions to look for differences in the developmental parameters of these congeneric species in southern California. Neonate larvae were introduced into eucalyptus logs in February, May, July, and October, and the infested logs were held in field cages at two locations: an inland desert site and a more temperate coastal site. Development times from neonate larva to emerged adult and percent emergence were recorded for beetles from all log cohorts at both sites. Under southern California climatic conditions, P. semipunctata seems to complete only one generation per year. Adult P. semipunctata emerged from infested logs from June to October. In contrast, P. recurva seems to be able to complete one generation and begin a second generation within the same year. Adult P. recurva emerged from infested logs from February to October. Across all treatments, a greater percentage of P. recurva (70 ± 2.5%) completed development in host logs than P. semipunctata (64 ± 1.5%). The majority of P. recurva (74.9%) and P. semipunctata (99.4%) emerged during June, July, and August. Host quality was correlated with beetle size. Overall, the differences in the developmental parameters of the two species may be contributing to the replacement of P. semipunctata by P. recurva in their shared habitat niche in southern California.

Sex pheromone of queens of the slave-making ant, Polyergus breviceps.

Abstract: The sex attractant pheromone produced in mandibular glands of queens of the slave-making ant Polyergus breviceps has been identified as a blend of methyl 6-methylsalicylate and 3-ethyl-4-methylpentanol. In field trials, each compound alone was completely unattractive to males, whereas blends of the two compounds attracted hundreds of males within a couple of hours.

( Z,Z )-11,13-Hexadecadienyl acetate and ( Z,E )-11,13,15-hexadecatrienyl acetate: synergistic sex pheromone components of oak processionary moth, Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae)

Abstract: Our objective was to identify sex pheromone components of the oak processionary moth, Thaumetopoea processionea (Lepidoptera: Thaumetopoeidae), whose larvae defoliate oak, Quercus spp, forests in Eurasia and impact human health Coupled gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric (MS) analyses of pheromone gland extract of female T processionea revealed two consistently EAD-active compounds They were identified as (Z,Z)-11,13-hexadecadienyl acetate (Z11,Z13-16:OAc) and (Z,E)-11,13,15-hexadecatrienyl acetate (Z11,E13,15-16:OAc) by comparative GC, GC-MS and GC-EAD analyses of insect-produced compounds and authentic standards In replicated field experiments (2000, 2001) in Nordbaden, Sudbaden and Sachsen-Anhalt (Germany), Z11,Z13-16:OAc and Z11,E13,15-16:OAc in combination, but not singly, attracted significant numbers of male moths It will now be intriguing to investigate whether Z11,E13,15-16:OAc, or its corresponding alcohol or aldehyde, serves as a pheromone component also in other species of the Thaumetopoeidae

Responses of Metaphycussp. nr. flavus to semiochemicals released from a scale host, Coccus hesperidum

Abstract: Metaphycus sp. nr. flavus (Encyrtidae: Hymenoptera) is a parasitoid species collected from the Mediterranean region which lays its eggs in the immature stages of several economically important soft scale insects (Hemiptera: Coccidae), including brown soft scale, Coccus hesperidum L. (= host insect). Preliminary tests suggested that the parasitoid is most successful in producing offspring when it oviposits in the younger stages of brown soft scale. In Y-olfactometer bioassays measuring wasp choices and residence times, naive parasitoids were significantly more attracted to yucca leaves infested with 26, 27, or 28 d-old scale than to uninfested leaves, whereas leaves with older (29-30 d-old) scale were no more attractive than uninfested leaves. Parasitoids also spent significantly more time in the arm with yucca leaves infested with 26 d-old scale than in the arm with uninfested leaves. These results are consistent with observations of the parasitoid’s reproductive success on scale of different ages, whereby older scale are more likely to encapsulate the developing eggs of M. sp. nr. flavusfemales than are younger scale. Further bioassays determined that yucca leaves that had been infested with 26 d-old scale but from which the scale had been removed were as attractive as infested leaves. In contrast, infested yucca leaves from which scale had been removed and the leaves subsequently washed with distilled water were less attractive than infested leaves. Furthermore, the wash water containing scale residues was attractive to female wasps. In total, these results suggest that Metaphycussp. nr. flavus females utilize volatile, water soluble compounds produced by brown soft scale as cues to locate suitable hosts.

Metaphycus species near flavus responses to semiochemicals released from a scale host, Coccus hesperidum.

Abstract: Metaphycus sp. nr. flavus (Encyrtidae: Hymenoptera) is a Mediterranean parasitoid species which oviposits in the immature stages of several economically important soft scale insects (Hemiptera: Coccidae), including brown soft scale Coccus hesperidum L. and C. pseudomagnolium (Kuwana). In Y-olfactometer bioassays measuring wasp choices and residency times, naive parasitoids were significantly more attracted to yucca leaves infested with 26, 27, 28, and 29 d-old scale than to uninfested leaves, whereas leaves with 30 d-old scale were no more attractive than uninfested leaves. Parasitoids also spent significantly more time in the arm with yucca leaves infested with 26, 27, 28, and 29 d-old scale than in the arm with uninfested leaves, but they spent substantially more time in the arm with a yucca leaf infested 26 d-old scale than in the arm of any other age class of scale. Further, yucca leaves that had been infested with 26 d-old scale but from which the scales had been removed were as attractive as infested leaves. However, yucca leaves that had been infested with 26 d-old scales but from which the scales had been removed and the leaves washed with distilled water were less attractive than infested leaves. When the wash water containing scale residues was used to impregnate a filter paper disk, the impregnated disk was more attractive than a control disk impregnated with distilled water. In sum, these results suggest that Metaphycus sp. nr. flavus females utilize volatile, water soluble compounds produced by brown soft scale as cues to locate suitable hosts. These results also suggest that 26-28 d-old scales are more attractive than older scales. Significantly, these are the scale ages on which M. sp. nr. flavus develops most successfully and suffers the least mortality from encapsulation. INTRODUCTION Brown soft scale, Coccus hesperidum Linnaeus (Hemiptera: Coccidae), is a cosmopolitan pest of agricultural and ornamental plants (Saakyan-Baranova 1964; Gill and Kosztrab 1997), and of plants in indoor plantscapes (Stauffer and Rose 1997). Dense scale populations feeding on these plants reduce plant vigor, kill twigs, reduce yields, and decrease visual appeal. The scale also produces honeydew on which sooty mould grows, which can further downgrade plant and fruit appearance. C. hesperidum often develops as colonies on a plant’s leaves and twigs because ants tend the scale to obtain honeydew, while protecting the scale from its natural enemies (Ebeling 1959; Gill 1988). In California, C. hesperidum usually occurs at low densities in citrus groves and on outdoor ornamental plants because several biological control agents suppress it in the absence of ants (Bartlett 1978, Bernal et al. 1998). Metaphycus species near flavus (Hymenoptera: Encyrtidae) was imported into California from Kosan, Turkey, in 1996 for release against a closely related scale, citricola scale, Coccus pseudomagnoliarum (Kuwana), which is a periodic pest of citrus in the San Joaquin Valley of California (Bernal et al. 1999). However, citricola scale has an annual life cycle and is difficult to rear in large numbers, so we mass produce M. sp. nr. flavus on brown soft scale (L. D. Forster, P. Pacheco, R. F. Luck, and J. Sinclair, in prep), a natural host for this parasitoid (Guerrieri and Noyes 2000). This strategy works well in providing large numbers of wasps for release but it remains unclear whether M. sp. nr. flavus reared from brown soft scale recognizes and utilizes citricola scale effectively. Thus, we sought: 1) to determine whether M. sp. nr. flavus uses volatile cues associated with C. hesperidum to locate this host and 2), to determine whether these cues are produced directly by the scale, by the plant in response to a scale infestation, or by some combination of the two if volatile cues are involved. MATERIALS AND METHODS Scale and parasitoid cultures A brown soft scale colony was established with scale obtained from a pineapple guava plant, Feijoa sellowiana O. Berg (Myrtaceae), located on the UCR, CA campus. We reared the scales on excised leaves of Yucca sp. (Lilliaceae) maintained hydroponically in the UCR insectary at 27-28°C, 60% R.H., and a 21L: 3D photoperiod (L. D. Forster, P. Pacheco, R. F. Luck, and J. Sinclair, unpubl. data). The excised leaves were obtained from yucca plants maintained on the Ag. Exp. Sta., UCR. We maintained the parasitoid colonies by introducing mated females into plastic tubes (7.5 cm diam. x 50 cm long) containing 1-2 scale-infested yucca leaves, streaked the inside of the tubes with honey, closed them with nylon-vented plastic caps, and maintained them at 25 ± 1°C and 50-70% R.H. under continuous light. Scale size was standardized at ca. 2.0 mm in width. After ca. 14 d, individual scales containing parasitoid pupae were isolated to obtain naive females (= no encounters with healthy scales). Newly