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Aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is a polyphagous insect species that migrates into the upper Midwest of the United States and the Western Canadian Prairies. Populations of this insect are associated with the transmission of a plant pathogen (Candidatus Phytoplasma asteris, 16SrI) to several annual crops and perennial plant species. Previous studies suggest that aster leafhoppers can sometimes prefer less suitable hosts for their development and survival, yet it is unclear if this lower performance on certain plant species is associated with reduced or impaired probing behaviors due to characteristics of the plants. To characterize the probing behaviors of aster leafhoppers, direct current electropenetrography recordings of male and female adults on barley (Polaes: Poaceae: Hordeum vulgare L.) were combined with plant histology, allowing the identification of nine waveforms and their proposed biological meanings. For each waveform, the number of waveform events per insect (NWEI), the waveform duration per insect (WDI), the waveform duration per event per insect (WDEI), and the percentage of recording time were calculated and statistically compared between sexes. Male and female aster leafhoppers exhibited similar behavioral responses for most of these variables, except for the NWEI for waveforms associated with nonprobing activities and the pathway phase. In these cases, male aster leafhoppers exhibited a higher number of events than females. Comparison of the proposed waveforms in this study with previous work on other hemipteran species provided additional support to the interpretation of the biological activities associated with each waveform. [ABSTRACT FROM AUTHOR]

In agricultural areas, the climatic conditions at the northern limit of crop cultures could impact pest regulation. In this paper, we study the aphid-parasitoid-hyperparasitoid network in cereal fields around Saskatoon (SK, Canada), one of the most harsh climatic conditions for cereal crops in the world, with an extremely short growing season. We have investigated the aphid-parasitoid-hyperparasitoid species relative abundances over two consecutive years. In 2014, a cold spring year, aphids were only found late in the growing season, and their arrival probably corresponded to late Southern winds. In 2015, aphids, parasitoids and hyperparasitoids arrived in the cereal fields in July and August, whereas the cereal harvest is typically complete by the end of the month of August. Three species of primary parasitoids were found for a total parasitism rate of 7.62%, and four genera of hyperparasitoids, with a hyperparasitism rate of 20.1%. There were 87.4% apterous aphids, and the proportion of apterous and winged (alate) aphids did not differ among the 3 aphid species, or among use by parasitoid species and hyperparasitoid species. The sex ratio of parasitoids in the complex was biased towards females for most of the species. In areas with extreme weather conditions and short growing seasons, effective biocontrol through parasitism is limited, although the synchronization level of parasitoids to their aphid hosts is high. We discuss the consequences of the limited length of the growing season on the provision of ecosystem services and on the seasonal ecology of insects of agronomic interest. We also provide information about morphological criteria for identification of parasitoids from the genus Aphidius. [ABSTRACT FROM AUTHOR]