Showing papers by "Jocelyn G. Millar published in 1997"

Reproductive Behavior of Thyanta pallidovirens (Heteroptera: Pentatomidae)

Abstract: Reproductive behavior of the stink bug Thyanta pallidovirens (Stal) was studied in the laboratory, including the determination of the sexual maturation period for both sexes, the effects of the number of copulations on fecundity, and the function of prolonged copulation. Mean premating periods for males and females were 3.6 ± 0.5 and 4.1 ± 0.6 d, respectively. Preoviposition period averaged 6.6 ± 0.9 d. Females preferred sheltered, roughtextured oviposition sites. Paired adults mated ≈13 times on average during their lifespan under laboratory conditions. The mean duration of copulations involving virgin females was >17 h, significantly longer than that of subsequent copulations, which lasted between 6.9 and 8.3 h. Multiple matings significantly increased female fecundity. Virgin males donated ≈17% of their body mass to a virgin female during mating. Duration of mating may be regulated by space available in the spermatheca for ejaculatory material. There was strong evidence of male mate choice, with males terminating copulation with small females before sperm was transferred. There was no indication of male mate-guarding behavior after copulation. Females almost always approached males from distances of >30 cm, suggesting that males attract females from a distance. Within 15 cm, males discern and approach females. Courtship behaviors of males included antennation of female antennae and abdomens, stroking the abdomens with the hind legs, and periodic male abdominal vibrations. Possible functions of these behaviors are discussed.

Sex Pheromone of the Mirid Bug Phytocoris relativus

Abstract: The sex attractant pheromone produced by adult females of the mirid bug Phytocoris retativus has been identified as a 2:1 blend of hexyl acetate with (E)-2-octenyl butyrate. The pheromone is stage-, sex-, and species-specific, attracting only adult male P. relativus. Hexyl acetate was identified in aeration extracts from both sexes, while (E)-2-octenyl butyrate was produced only by females. Both males and females also produced hexyl butyrate and octyl acetate, while only females produced (E)-2-hexenyl and octenyl acetates, and (Z)-3-octenyl acetate. The function(s) of these chemicals were not determined. Attraction of males increased with dose, with doses of 0.1 to 33 mg loaded on grey rubber septa. Attractiveness of rubber septum lures decreased quickly with age due to the volatility of the two pheromone components.

Growth Inhibitory, Insecticidal, and Feeding Deterrent Effects of (12Z, 15Z)-1-Acetoxy-2-Hydroxy-4-Oxo-Heneicosa-12,15-Diene, a Compound from Avocado Fruit, to Spodoptera exigua

Abstract: We isolated and identified (12Z,15Z)-1-acetoxy-2-hydroxy-4-oxoheneicosa-12,15-diene (persin) from avocado as a compound toxic to Spodoptera exigua larvae. Persin was obtained from oil extracted from the specialized idioblast cells of avocado fruit. When tested for activity using neonates in no-choice artificial diet bioassays, persin at concentrations of 200 μg/g inhibited growth; larvae gained only ∼50% of the weight attained by control insects after seven days. At concentrations of 400 μg/g or above, larval growth was reduced by >70% as measured by weight gain, and significant mortality occurred. In choice tests, persin at concentrations of 400 μg/g or higher deterred feeding, with significantly more larvae being found on control diet than on persin-treated diet. Possible applications of persin as a natural insecticide are discussed.

Enlisting an Underappreciated Clientele: Public Participation in Distribution and Evaluation of Natural Enemies in Urban Landscapes

Abstract: Since the turn of the century, there has been a significant shift in the population of the United States from a rural to a predominately urban and suburban society. The process of urbanization created new landscapes to replace the natural areas or farms that previously occupied the land. To a great extent, these landscapes are artificial communities comprised of diverse assemblages of native and exotic species that may be comparable in diversity to tropical rain forests (Owen 1983). With respect to woody ornamental plants alone, Frankie and Ehler (1978) reported 322 species (132 species of trees, 147 species of shrubs, and 53 species of vines and ground covers) were planted in Austin, TX, and 123 species of trees were planted in Berkeley, CA. In total, 318 plant species, including 143 native and 175 non-native, exotic species, were planted in a single study garden in Leicester in the United Kingdom (Owen 1983). These urban landscapes, which include both annual and perennial species planted at densities or separations not normally found in natural habitats, also are characterized by high levels of patchiness and structural diversity (Owen 1983, Flanders 1986). In addition, the physical barriers associated with buildings, transportation corridors, parks, and industrial complexes add significant levels of artificial spatial complexity to the environment (Frankie and Ehler 1978).

Pecan Nut Casebearer (Lepidoptera: Pyralidae) Sex Pheromone Used To Monitor Phenology and Estimate Effective Range of Traps

Abstract: Sex pheromone traps for pecan nut casebearer, Acrobasis nuxvorella Neunzig, were deployed at densities of 1, 2, and 4 traps per tree in blocks of 9 trees or in single, isolated trees replicated 4 times in an isolated, vegetatively propagated pecan orchard in western Texas to examine male moth activity. The phenology of overwintering generation pecan nut casebearer male moth activity was consistent among the 6 treatments. Male moth capture per trap tended to decrease as traps per tree increased, but captures per tree were not significantly different among the 6 treatments, indicating an effective catch area of 1 tree for a trap. Catch differences were found among trees within the 9-tree blocks, with fewer moths caught in traps within the center tree and more captured in the southwestern tree, west tree column, and south tree row. Trap lines extending away from the orchard caught few moths. Pheromonebaited traps show merit in detecting moth phenology and may have application in assessing moth density for making pest management decisions.