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Illustrated identification keys are given for the superfamilies/families of insect parasitoids and the subfamilies, genera, and species of Braconidae reared from species of Choristoneura Lederer in the Nearctic Region. Goniozus floridanus (Ashmead) (Chrysidoidea: Bethylidae) represents the third superfamily of Hymenoptera, and Colpoclypeus florus (Walker) (Hymenoptera: Eulophidae) is added to the list of Chalcidoidea recorded from Choristoneura. Fifty species of Braconidae in 18 genera and 9 subfamilies are recorded parasitizing 11 Choristoneura species; almost half belong to the Microgastrinae. Eight braconids (16%) were found for the first time as parasitoids of Choristoneura. The first host record is given for Oncophanes californicus (Ashmead) (Hormiinae). Known insect parasitoids of Choristoneura spp. in the Nearctic Region include 230 species in 106 genera, about 75% of which attack only 1 or 2 Choristoneura species each. An additional 36 species are considered incorrectly associated with Choristoneura, an error rate of 14%. The Banchinae (Ichneumonidae, especially Glypta Gravenhorst), Pimplinae (Ichneumonidae), and Microgastrinae (Braconidae) made up the greatest proportion of parasitoids. No parasitoids have yet been recorded from five Nearctic Choristoneura species.
Mitochondrial DNA cytochrome c oxidase subunit 1 (DNA barcode) and nuclear microsatellite flanking region sequences were used to analyse populations of putative “sugarbeet root aphid”, Pemphigus betae Doane, from sites in Alberta, Canada. Three sympatric genotypes were revealed, identified as P. betae, P. populivenae Fitch, and an undetermined third species. All three genotypes formed morphologically indistinguishable galls on the same set of cottonwood (Populus L., Salicaceae) host species, often on the same tree. Gall morphology is frequently used to identify Pemphigus species. Our results indicate that this practice may be unreliable for these three taxa at least.
Physiology, Biochemistry, Development and Genetics
Fluctuating asymmetries (FAs) are small random deviations between left- and right-side measurements of normally symmetrical traits in a given organism. Changes in FA have frequently been proposed as biomarkers for organisms exposed to stress during development and may have value for detecting low levels of chemical residues or other stressors in the environment. We tested this hypothesis in three replicated laboratory experiments and failed to find any effect of chemical residues (ivermectin) in cattle dung on levels of FAs (wing and leg traits) for the dung-breeding fly Scathophaga stercoraria L. (Diptera: Scathophagidae). In trying to resolve this discrepancy with previous reports, we found that many studies failed to replicate measurements of FA traits within an experiment, which increases the likelihood of spurious positive results. Furthermore, experiments were rarely replicated either within or between studies, so the repeatability of positive results has usually gone untested. These issues have been raised by others, but are still not being adequately addressed. Discussions regarding the value of FAs as biomarkers will not advance until this is done.
A pilot-scale industrial microwave unit operating at 2450 MHz was used to test whether microwave treatment can control Tribolium castaneum (Herbst) populations infesting stored rye, Secale cereale L. (Poaceae). Tests were performed in samples of rye (50 g) with 14%, 16%, or 18% moisture content. Samples containing T. castaneum eggs, larvae, pupae, or adults were exposed to 200, 300, 400, or 500 W for periods of 28 or 56 s, resulting in final surface temperatures ranging from 47.2 to 83.9 °C. Eggs were most vulnerable; adults were least vulnerable. Subsequent tests showed that microwaves reduced rye germination and flour yield. No effect of treatment on grain protein content, falling number, sodium dodecyl sulfate sedimentation volume, mixograph and farinograph dough development times, or baking properties was detected.
Dendroctonus armandi Tsai and Li is an important native pest of Chinese white pine (Pinus armandii Franch. (Pinaceae)) in the Qinling Mountains of Shaanxi Province, People's Republic of China. Populations can reach epidemic levels and cause widespread mortality of trees in forest ecosystems. We studied the flight behaviour of D. armandi collected under controlled conditions using a flight-mill system to gather information to aid in its management. Our results indicate that D. armandi has three distinct flight patterns (intermittent flight, short-burst flight, and sustained uninterrupted flight). There were no significant differences in flight performance between males and females. Median daily values for total distance traveled, total flight time, and maximum uninterrupted flight time were 275.1 m day-1, 815 s day-1, and 40 s day-1, respectively (n = 148). Individuals displayed positive phototactic behaviour: total flight distance and total flight time were greater under artificial illumination than in natural light or darkness. The level of flight activity increased throughout the morning, remained high during the afternoon (1400–1600), dropped considerably at 1800, and was lowest at midnight. There was no significant difference in flight distance or flight time between the first and second generations. From the data collected, it is clear that the phototactic response is an important factor in the flight behaviour of D. armandi and may influence its spatial dispersal.
Laboratory observations revealed that late-instar larvae of the eastern spruce budworm (Choristoneura fumiferana (Clemens)) (Lepidoptera: Tortricidae) spend most of their time spinning, wandering, and resting; less than 10% is spent feeding. Larvae feed in a discontinuous pattern of short feeding bouts separated by much longer intervals of nonfeeding activity. Over a 2 h observation period, feeding bouts averaged 2.2 min and were separated by 17.4 min intervals for 4th-instar larvae as compared to 3.3 min bouts separated by 33.4 min intervals for 5th-instar larvae. The duration of a feeding bout was positively correlated with the duration of the subsequent interval, not with the duration of preceding intervals, suggesting that feeding-bout frequency is governed primarily by post-ingestion processes. It is postulated that short feeding bouts followed by long intervals limit the window for ingesting an efficacious dose of aerially applied insecticides such as Bacillus thuringiensis.
Leek moth, Acrolepiopsis assectella, recently became established in the Ottawa Valley, where it significantly damages garlic, leek, and onion (Allium L., Liliaceae) crops. At a threshold of 7 °C, populations in eastern Ontario require 444.6 day-degrees to develop from egg to adult. Pheromone-trap data identify spring, early-summer, and late-summer flight periods of overwintered 1st- and 2nd-generation adults, respectively. Depending on ambient temperatures, the life cycle takes 3–6 weeks in the field, with three generations possible. Management strategies such as application of reduced-risk foliar insecticides and use of row covers require precise timing to target appropriate life-cycle stages. Implementation windows can be determined by incorporating pheromone-trap data and ambient air temperature into a life-cycle development model. A proposed integrated pest management program will involve the use of pesticides, mechanical barriers, and classical biological control.
Soybean oil (SO) is considered an active ingredient in commercial BiteBlocker™ insect-repellent products. Our objective was to test mechanisms by which SO exhibits repellency, using the yellow fever mosquito, Aedes aegypti (L.) (Diptera: Culicidae), as a representative blood-feeding insect. In dual-port glass-cage olfactometers, human hands treated with SO at various concentrations attracted as many mosquitoes as did untreated hands, indicating that SO has no long-range repellent effect. In contrast, hands treated with N, N-diethyl-3-methylbenzamide (DEET) attracted significantly fewer mosquitoes than did untreated control hands. In cage experiments, treating an area of a human forearm exposed to A. aegypti with SO provided no protection against bites, whereas treating it with DEET did. These results indicate that SO has no short-range or contact repellent properties. Both DEET and the BiteBlocker™ product conferred protection for periods similar to those previously reported. Based on our data, classification of SO as an active mosquito repellent should be reconsidered.