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For more than 100 yrs, the wheat stem sawfly (WSS) Cephus cinctus Norton (Hymenoptera: Cephidae), has been a destructive pest of cereal crops in the Northern Great Plains. WSS infestation levels >70% have been reported, and economic loss from crop damage caused by this insect can be as high as $80 million (USD) per year in the state of Montana alone. Contact insecticides are not effective against WSS because the larvae and pupae are protected inside the plant stem, and the development of solid-stem cultivars have not resulted in sufficient declines in WSS populations. Biological control offers the best hope for achieving economical and sustainable management of WSS. However, development and advancement of WSS biological control strategies has been limited in recent years. Presently, there are three main types of biologicals available for managing WSS: two native hymenopteran parasitoids, entomopathogenic nematodes, and entomopathogenic fungi. Here, we present the most current research regarding the use of these biologicals against WSS, and we discuss new strategies and research opportunities for improving their effectiveness for managing this persistent pest. It is unlikely that a single agent will produce the desired results, but by increasing pressure from all three sources, their combined impact may more reliably cause significant reductions in WSS infestations. Eradication of WSS, a native species, is not a realistic goal, but it is probable that WSS populations will decline more readily as biological control methods continue to advance.
A growing number of studies indicate an association between symbiotic microbes and insecticide resistance in a diverse range of insects. However, the prevalence, possible mechanisms, and wider implications of this phenomenon remain unclear. While evidence suggests that in some cases insecticide resistance correlates with changes in the microbial community as a result of tradeoffs between physiological parameters in the host, other work implicates specific microbes as causal agents of resistance. Here, we review relevant literature pertaining to symbiont-associated insecticide resistance and suggest avenues of research that may help shed new light on this important phenomenon.
Shifts of functional traits are important because phenotypic responses of species to environmental changes caused by natural and anthropogenic disturbances are fundamental in determining the risk of population extinction. This study tested the effect of forest thinning on the body shape and male genital size of an endemic ground beetle species Carabus masuzoi (Imura and Satô 1989) (Coleoptera, Carabidae) in cypress plantations started approximately 30 yr ago in central Taiwan. The beetles were sampled and compared from 1) natural broadleaf forest, 2) non-thinned cypress plantation, and 3) 45% thinned cypress plantation. Female prothorax length from the non-thinned plantation was significantly greater than that of the natural forest, and the 45% thinned plantation had a higher frequency of the small (S-type) and a lower frequency of the large (L-type) male genitalia than in the natural forest. The results indicated that, within a short ecological time frame, the prothorax shapes and male genital sizes of C. masuzoi populations might respond to changes induced by different forest types and forest thinning, respectively. We hypothesized that the difference in prothoracic shape was related to locomotory ability in forest understories, whereas the changes in male genital sizes might have been a result of different levels of intraspecific sexual selection, random effects of population fluctuations/dispersal, or pleiotropy.
While the alternation of asexually and sexually reproducing generations is common among the oak gall wasps (Hymenoptera: Cynipidae: Cynipini), it has been hypothesized that the diversity of taxa displaying this unique life cycle is underestimated because either 1) the alternative generation has not yet been described or 2) each generation is currently described as two distinct species and should be collapsed into one heterogonic organism (referred to as ‘closing the life cycle’).Through field observations, experimental rearing, morphological identification, laboratory behavioral assays, and genetic analysis, we demonstrate heterogony in the cynipid species Andricus quercuslanigera (Ashmead 1881) (Hymenoptera: Cynipidae), which was previously only described from the asexual generation. We confirm that the asexual generation, which develops in ‘fuzzy’ galls on the central vein on the underside of leaves on live oaks in southeast Texas, Quercus virginiana, represents only one generation in a bivoltine life cycle that alternates with a newly discovered sexual generation that develops in galls on catkins on the same host. Our study highlights the need for detailed inspections of the life cycles of unisexual gall wasp species and we discuss the closure of the A. quercuslanigera life cycle in light of recent advances in the study of the ecology and evolution of heterogony in the Cynipidae.
Date palm hooper is one of the most important pests on date palms with many highly diverged populations varied in damaging rate and preferring host cultivar. Current and potential geographic distribution of date palm hopper, Ommatissus lybicus (de Bergevin; Hemiptera: Tropiduchidae) in Iran was modeled using the Maxent procedure. Point sampling data sets included latitude, longitude, and altitude and were augmented with data on 19 bioclimatic variables retrieved from WorldClim dataset for use as predictor variables in Maxent. Maxent results demonstrated that northwest Sistan-Baluchestan, east, south and southeast Kerman, northeast and northwest Hormozgan and small districts of Bushehr provinces are hot spot habitats for O. lybicus in Iran. Jackknife analysis revealed that precipitation of warmest quarter was the most influential explanatory variable in determining distribution of O. lybiucs in Iran. Moreover, curve response and frequency distribution analyses revealed that annual mean temperature was the most predictive factor of the distribution of O. lybicus. Discontinuity in predicted hot spot habitats of O. lybicus was consistent with the genetic structure recorded for this species. Our study represents valuable information that can inform pest management strategies aimed at preventing population expansion and niche shift.
Predatory wasps are one of the few natural enemies to attack late instar pentatomid nymphs and adults. However, there is a substantial lack of information about their flight and nesting behavior, making them poorly understood. We report 3 yr of observational data of Astata unicolor Say 1824 foraging behavior and phenology from a residential site in Portland, OR. A. unicolor attacked and paralyzed at least four hemipteran species, and 64% of paralyzed prey were from the invasive Halyomorpha halys (Stål; Hemiptera: Pentatomidae). Peak flight occurred between late July and mid-September. Though unmanaged and solitary, A. unicolor's preference for H. halys demonstrates that native predators contribute to mortality and potentially management of economically important insects. This is one of the few studies to document predatory wasps' potential for biological control of H. halys. Additional work on Astata is necessary to determine whether trap nesting, dispersal, or habitat enhancement, broadens the potential for expanded biological control.
The management of overwintering honeybee colonies is pivotal for the apiculture industry in China. To investigate the molecular mechanisms involved in the seasonal regulation of the development of Apis mellifera carnicas hypopharyngeal gland (HG), transmission electron microscopy (TEM), and large-scale proteomics (isobaric tag for relative and absolute quantification; iTRAQ) were employed. In total, 3,025 proteins were identified at two-time points: winter (constituting group A) and early spring (constituting group B). Among them, 24 proteins were quantified and compared to identify their differential expression patterns. The TEM profiles and iTRAQ analysis results might aid in understanding the molecular mechanisms associated with the seasonal changes in honeybee HG. For example, the acinar cells of spring worker honeybees had more mature organelles. Furthermore, the ribosomal structures and protein biosynthesis were strengthened. However, the amount of exocrine royal jelly produced could not have satisfied the demand of the feeding larvae and queen. Honeybees might suffer reduced immune function during their feeding stage. The present study elucidates the regulatory mechanisms of HG on overwintering and spring arousal in honeybees. The results might provide a practical and theoretical guideline for the overwintering management program of the apicultural industry.
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