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Labena Cresson is a large Gondwanan genus best represented in the Neotropical area. We describe three new species in the Neotropical Labena striata species group: Labena gauldiana sp. nov. from Costa Rica and Mexico, Labena yucatanicasp. nov. from Mexico, and Labena iquitosicasp. nov. from Peruvian Amazonia. These species are among the largest and most spectacular Neotropical Ichneumonidae ever collected. We also provide additional descriptive remarks regarding Labena striata Townes and Townes (including intraspecific variation) and an identification key to the six species of the striata group.
We review the Neotropical genus Cartagonum Pic, redescribing C. bernardi Pic and describing two new species, Cartagonum apiubasp. nov. and Cartagonum mayensesp. nov. New collection records, a key to species, and illustrations of somatic and genitalic characters are provided. Species of Cartagonum. are now known to be distributed from Colombia to southern Mexico and southeastern Brazil.
Physiology, biochemistry, development and genetics / Physiologie, biochimie, développement et génétique
Worldwide biological-control research has shown that the fungal entomopathogen Metarhizium anisopliae (Metschnikoff) is an alternative to chemical insecticides for controlling grasshoppers and locusts. The pathogenicity of two recently discovered isolates of M. anisopliae var. anisopliae Driver and Milner from Canadian soil to the key grasshopper pest Melanoplus bivittatus (Say) and the yellow mealworm, Tenebrio molitor L., was determined by means of laboratory bioassays. Insects were fed a single dose of 105 conidia suspended in sunflower oil on food (a standard-size lettuce wafer). Subsequent feeding activity, movement, and mortality were assessed daily. The isolates were equally pathogenic, and similar in pathogenicity to the industry standard, Green Guard (M. anisopliae var. acridum Driver and Milner). Treatment with the three isolates resulted in 50% grasshopper mortality in 5–6 days and 90% mortality in 6–7 days.
Larvae of Abagrotis orbis (Grote) (Lepidoptera: Noctuidae) are climbing cutworms and can damage grapevines, Vitis vinifera L. (Vitaceae), in early spring by consuming expanding buds. A sex attractant would be useful for monitoring this insect in commercial vineyards. (Z)-7-Tetradecenyl acetate and (Z)-11-hexadecenyl acetate were found in extracts of female abdominal tips. In multiple field experiments, male A. orbis were captured in traps baited with a combination of these two chemicals but not in traps baited with either chemical alone. Males were trapped from mid-September to early October in south-central Washington and south-central British Columbia. Other noctuid moths (Mamestra configurata Walker, Xestia c-nigrum (L.), and Feltia jaculifera (Guenée)) were also captured in traps baited with the A. orbis pheromone and may complicate the use of this lure to monitor A. orbis. Abagrotis discoidalis (Grote) was captured in traps baited with (Z)-7-tetradecenyl acetate but not in traps baited with the two chemicals together.
Biodiversity and evolution / Biodiversité et é volution
Ground beetles (Coleoptera: Carabidae) were sampled in conventional and genetically modified herbicide-tolerant (GMHT) corn, Zea mays L. (Poaceae), planted under rotation with canola, Brassica L. (Brassicaceae), or continuously cropped corn to investigate the influence of corn variety and rotation on the structure of carabid assemblages. Corn variety, cultivation regime, and their interaction all influenced overall carabid activity density. Weed management associated with corn variety influenced the activity density of a few carabid species and this was attributed to changes in vegetation. Some smaller bodied carabids such as Bembidion quadrimaculatum L. were less abundant in GMHT plots, probably because weed density was higher in midseason, but the opposite was observed for larger bodied carabids such as Pterostichus melanarius (Illiger). Overall, rotating corn with canola had a stronger effect on carabid community structure than did corn variety. We suggest that GMHT corn has little impact on the overall carabid fauna but may influence the activity of certain species through effects on the weed community.
Canadian peatlands are subject to disturbance and destruction, and drainage for agriculture is responsible for 85% of this degradation. Few studies have explicitly addressed the effects of habitat degradation on arthropod diversity in Nearctic peatlands. Because higher Diptera (Brachycera) in peatlands are diverse, are an important component of food webs, and exhibit a wide range of ecological requirements, we examined species richness, abundance, and community composition of Brachycera across transects at 1, 6, and 11 m from a collector drainage ditch in Johnville Bog and Forest Park, Quebec. In total, 1453 Brachycera were collected, representing 24 families and 166 species. Species diversity (based on Simpson's diversity index) and rarefaction-estimated species richness were higher at 6 and 11 m than at 1 m from the ditch, probably because of the homogeneous moss cover and moister conditions at greater distance from the ditch. Species composition also differed between 1 m and other distances, based on cluster analysis, multiresponse permutation procedures analysis, and the presence of five predaceous species that were significant indicator species 1 m from the drainage ditch. Our results suggest that anthropogenic degradation of hydrological conditions may be responsible for the low species richness and high dominance of a few species currently seen at the ditch margin.
Eighteen species of cutworm moths were collected as larvae feeding at night on grapevines, Vitis sp. L. (Vitaceae), in south-central British Columbia, Canada, during April and May from 2004 to 2008. Ten species belonged to two genera, Abagrotis Smith and Euxoa Hübner. Abagrotis orbis (Grote), A. nefascia (Smith), and A. reedi Buckett accounted for over 85% of cutworms reared to adulthood. Abagrotis orbis and A. reedi were found in all locations; the former accounted for nearly 90% of larvae collected from vineyards on warm sandy soils. Abagrotis nefascia was largely restricted to cooler sites with heavier soils. For laboratory-reared A. orbis, pupal mass was highest and sex ratios were approximately equal when larvae were reared either on a pinto bean-based diet prepared with the recommended amount of water or on a commercial black cutworm diet and 50% of the recommended water. Survival to adult eclosion was significantly higher on the black cutworm diet, but because this was thicker than the pinto bean-based diet it was impractical to use. To date, A. orbis, A. nefascia, and A. reedi have been laboratory-reared continuously on artificial diet for more than six generations.
The discovery in southwestern British Columbia of widespread established populations of the Palaearctic leafminer Heterarthrus vagans (Fallén) feeding on native red alder, Alnus rubra Bong. (Betulaceae), is reported. A preliminary survey suggests that it is currently confined to the Fraser Valley west of Hope, its distribution extending north along Howe Sound almost to Squamish. It was not found in the greater Victoria area. No other regions of the province have been surveyed. This introduced sawfly completes at least two generations a year. Diagnostic characters to aid the recognition of adults and feeding larvae of H. vagans and a modified key to adult Heterarthrinae on Betulaceae are provided.
Monitoring of pear psylla (Cacopsylla pyricola (Förster), Hemiptera: Psyllidae) prior to spring bud break could aid in predicting the size of subsequent spring populations and lead to improved proactive management decisions. Yellow traps are commonly used to monitor hemipteran pests including pear psylla, but very little is known regarding seasonal changes in attractiveness of yellow traps or relative attractiveness of colours other than yellow. This study presents seasonal colour-trap preferences of pear psyllas based on pear (Pyrus communis L., Rosaceae) phenological stages in the mid-Atlantic region of the United States of America. Black, blue, brown, clear (colourless), green, orange, red, white, and yellow traps were assayed against wild adult psylla populations over a 2-year period. Pear psyllas had a strong preference for yellow and orange when green leaves were present; however, we found no statistically significant difference between traps of different colours prior to spring bud break. Significantly more female psyllas were caught overall, but there was no gender-based colour bias. None of our colour traps caught significantly fewer psyllas than did clear (background hue) traps, suggesting that no traps were repellent.