Karen R. Sime

Diachasmimorpha longicaudata and D. kraussii (Hymenoptera: Braconidae), potential parasitoids of the olive fruit fly

Abstract The olive fruit fly, Bactrocera oleae (Tephritidae), is a significant threat to Californias olive industry. As part of a classical biological control program started in 2002, the parasitoids Diachasmimorpha kraussii and D. longicaudata (Hymenoptera: Braconidae) were imported to California from laboratory colonies in Hawaii. Studies on their biology and behavior as parasitoids of the olive fruit fly were conducted in quarantine. Both species tend to oviposit into 2nd and young 3rd instars, with the offspring completing development in the flies’ puparia. Most eggs are deposited in the first two weeks of adult life. Observed lifetime fecundity was low, possibly as a consequence of the relatively poor quality of the harvested olives used as a host substrate. Both pre-imaginal development and adult longevity were limited at constant temperatures above 30°C, which may indicate that these species will have difficulty establishing in the warmest regions of California.

Mortality of olive fruit fly pupae in California

Abstract Efforts to control the olive fruit fly, Bactrocera oleae (Diptera: Tephritidae), in California have focused on insecticidal baits and biological control by parasitoids, which primarily target the adult and larval stages, respectively. The pupal stage, which occurs in the soil, has largely been overlooked. This study investigated mortality factors for olive fruit fly pupae in California olive orchards, using a combination of exclusion experiments and observation and trapping of potential predators. Results show predation and climatic factors contribute to pupal mortality. Ants (Formicidae) were the most numerous predators observed. Soil-borne pathogens caused no mortality in this study. Potential applications of these results in the development of a sustainable management program are discussed.

Testing Baits to Control Argentine Ants (Hymenoptera: Formicidae) in Vineyards

Abstract Liquid baits were evaluated for control of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), and associated mealybug and soft scale pests in California vineyards. In 2003, liquid baits with small doses of imidacloprid, boric acid, or thiamethoxam dissolved in 25% sucrose water resulted in lower ant and mealybug densities and fruit damage, compared with an untreated control. Similar treatments in a soft scale-infested vineyard showed only a reduction of ant density and fruit infestation in only the boric acid and thiamethoxam treatments. In 2004, commercial and noncommercial formulations of liquid baits reduced ant densities in three separate trials, but they had inconsistent effects on mealybug densities and fruit infestation; granular protein bait had no effect. Using large plots and commercial application methodologies, liquid bait deployed in June resulted in lower ant density and fruit infestation, but it had no effect on mealybug density. Across all trials, liquid bait treatments resulted in lower ant density (12 of 14 trials) and fruit damage (11 of 14 sites), presenting the first report of liquid baits applied using commercial methodologies that resulted in a reduction of ants and their associated hemipteran crop damage. For commercialization of liquid baits, we showed that any of the tested insecticides can suppress Argentine ants when properly delivered in the crop system. For imidacloprid, bait dispensers must be protected from sunlight to reduce photodegradation. Results suggest that incomplete ant suppression can suppress mealybug densities. However, after ant populations are suppressed, there may be a longer period before hemipteran populations are effectively suppressed. Therefore, liquid baits should be considered part of a multiseason program rather than a direct, in-season control of hemipteran pest populations.

Opportunistic out-crossing in Nicotiana attenuata (Solanaceae), a predominantly self-fertilizing native tobacco

BackgroundAlthough Nicotiana attenuata is entirely self-compatible, chemical and other floral traits suggest selection for the maintenance of advertisement for moth pollinators.ResultsExperimental exclusions of pollinators from plants with emasculated flowers in natural populations in southern Utah during an outbreak of the hawkmoth Hyles lineata revealed that 24% of the seed set could be attributed to insect pollination, and eliminated wind pollination and apomixis as contributing to seed set. Hence these moths can mediate gene flow when self-pollen is unavailable. To quantify gene flow when self-pollen is available, plants were transformed with two marker genes: hygromycin-B resistance and β-glucuronidase. The utility of these genetic markers to measure gene flow between plants was examined by mixing pollen from plants homozygous for both genes with self-pollen in different ratios and hand-pollinating emasculated flowers of plants growing in a natural population. The proportion of transformed seeds was positively correlated with the amount of transformed pollen applied to stigmas. In glasshouse experiments with the hawkmoth Manduca sexta and experimental arrays of transformed and wild-type plants, pollination mediated by moths accounted for 2.5% of the seed set.ConclusionsEven though moth pollination is rare and highly variable for this largely selfing plant, N. attenuata opportunistically employs a mixed-mating system.

A Comparison of Two Parasitoids (Hymenoptera: Encyrtidae) of the Vine Mealybug: Rapid, Non-Discriminatory Oviposition Is Favored When Ants Tend the Host

ABSTRACT The encyrtid parasitoids Coccidoxenoides perminutus Girault and Anagyrus nr. sp. pseudococci (Girault) were compared in the laboratory as parasitoids of the mealybug Planococcus ficus (Signoret). Female C. perminutus preferred second-instar P. ficus for oviposition, and produced more adult offspring (149.3 per female) than A. nr. sp. pseudococci (54.1 per female). The development time, from egg to adult emergence, of C. perminutus decreased with increasing constant temperatures between 18.5 and 30.1°C; at lower (12.0 and 15.0°C) and higher (31.1, 32.7, and 34.2°C) temperatures, the parasitoid did not develop. The lower threshold was calculated by linear methods to be 10.97°C, and the thermal constant was calculated to be 507.98 degree—days. The development times of C. perminutus were longer than those of A. nr. sp. pseudococci, and C. perminutus had narrower temperature tolerances than P. ficus or A. pseudococci. Argentine ants (Linepithema humile (Mayr)) reduced the amount of time C. perminutus foraged on mealybug-infested squash, but did not affect the number of oviposition attempts or offspring produced, whereas Argentine ants reduced A. nr. sp. pseudococci foraging time, oviposition attempts, and number of offspring obtained. Overall, the results suggest that under certain conditions, including optimal conditions of temperature and host-stage availability, C. perminutus outperforms A. nr. sp. pseudococci, and may be an effective augmentative control agent even when ants are tending the hosts. However, temperature limitations and host-stage selection behaviors would reduce C. perminutus performance in the field, and in the absence of ants, other parasitoids may be favored.

A revision of the genus Trogus (Hymenoptera: Ichneumonidae, Ichneumoninae)

Abstract The ichneumonine genus Trogus is revised, with descriptions, diagnoses and a key provided for the twelve recognized species. The species treated herein are: T. crustosus Wahl, sp.n.; T. edwardsii Cresson (= T. fletcherii Harrington, Macrojoppa californica Cresson syn.n.); T. flavipennis Cresson; T. fulvipes Cresson (= Trogus apicatus Davis); T. ixcuinae Wahl, sp.n.; T. koreensis Wahl, sp.n.; T. lapidator (Fabricius) (= Ichneumon coerulator Weber, Ichneumon coerulator Fabricius, Ichneumon saxator Gravenhorst, Trogus fuscipennis Gravenhorst syn.n., Psilomastax violaceus Mocsáry syn.n., Trogus cyaneipennis Costa syn.n., Psilomastax cyaneus Kriechbaumer syn.n., Trogus lapidator romani Uchida syn.n., Trogus lapidator brevicaudae Heinrich syn.n., Trogus lapidator panzeri Carlson syn.n.); T. pennator (Fabricius); T. picadoae Wahl, sp.n.; T. pompeji (Kriechbaumer); T. thoracicus (Cresson); T. vulpinus Gravenhorst (= T. exesorius Brullé, Dinotomus vulpinus var. nigrithorax Strand syn.n., T. pennator ssp. argutus Heinrich syn.n.). A critical review and examination of preserved host material confirmed that Trogus specializes on the Papilionidae. Finer patterned host use within the genus is attributed to the chemistry of hosts and their food plants. Several Trogus species are polyphagous within the Papilionidae with substantial overlap amongst host ranges, indicating that ecological opportunism rather than host–parasite coevolution has most influenced the evolution of the genus.

Evidence for Population Differentiation in the Bog Buckmoth of New York State

Abstract Hemileuca maia (Bog Buckmoth; Saturniidae) is a rare, ecologically unique variant of the Hemileuca maia complex known only from ten wetlands in the Great Lakes region of North America. The Bog Buckmoths status as a threatened taxon meriting conservation has been subject to a debate largely centered on its degree of evolutionary isolation and species status. We studied the genetic variation of two New York Bog Buckmoth populations using amplified fragment-length polymorphisms (AFLP). Bayesian clustering analysis identified two genetically distinct population clusters, with membership that did not coincide consistently with the two sampled populations. There appears to be either historical or contemporary gene flow between Bog Buckmoth populations, with the results suggesting either dispersal between the two sampled populations or contributions from a third unsampled population. Genetic diversity levels were similar. These findings argue for the utility of population-level analyses of Bog Buckmoth as a tool in conservation practice as well as in understanding the taxons evolutionary history.