Assessing the role of generalist predators in the biological control of alfalfa weevil (Coleoptera: Curculionidae)

2017 ◽  
Vol 149 (4) ◽  
pp. 525-533 ◽  
Author(s):  
Tatyana A. Rand

AbstractAlfalfa weevil (Coleoptera:Curculionidae) is a major pest of alfalfa throughout the United States of America. Biological control research has disproportionately focussed on introduced parasitoids. Generalist predators may also be important, but experimental work evaluating their impacts is lacking. I combined a cross-site survey with a predator exclusion experiment to identify key predators, and test for impacts on weevil survival and plant defoliation levels in Montana and North Dakota, United States of America. Spiders (Araneae) dominated the complex, followed by Nabidae (Hemiptera) and Coccinellidae (Coleoptera). None of the dominant predators showed aggregative responses to weevil (Hypera postica (Gyllenhal); Coleoptera: Curculionidae) or pea aphid (Acyrthosiphon pisum (Harris); Hemiptera: Aphididae) densities across 10 sites surveyed. However, weevil densities were positively correlated with both coccinellid and nabid densities across transects at the experimental site. Thus, predator groups traditionally associated with aphids can show strong aggregative numerical responses to alfalfa weevil larvae at smaller scales. Predator exclusion revealed no significant predator effects on larval survival or alfalfa damage. However, final densities of pea aphids were significantly higher in exclusion treatments relative to controls. The results suggest that even under conditions where predators exert significant pressure on aphids, they may still have minimal impacts on weevils. Additional experimental work is necessary to determine the broader potential of generalist predators as alfalfa weevil control agents.

2015 ◽  
Vol 147 (3) ◽  
pp. 300-317 ◽  
Author(s):  
Leah S. Bauer ◽  
Jian J. Duan ◽  
Juli R. Gould ◽  
Roy Van Driesche

AbstractFirst detected in North America in 2002, the emerald ash borer (EAB) (Agrilus planipennis Fairmaire; Coleoptera: Buprestidae), an invasive phloem-feeding beetle from Asia, has killed tens of millions of ash (Fraxinus Linnaeus; Oleaceae) trees. Although few parasitoids attack EAB in North America, three parasitoid species were found attacking EAB in China: the egg parasitoid Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae) and two larval parasitoids Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) and Spathius agrili Yang (Hymenoptera: Braconidae). In 2007, classical biological control of EAB began in the United States of America after release of these three species was approved. In 2013, release of the larval parasitoids was approved in Canada. Research continues at study sites in Michigan, United States of America where the establishment, prevalence, and spread of O. agrili and T. planipennisi have been monitored since 2008. However, establishment of S. agrili remains unconfirmed in northern areas, and its release is now restricted to regions below the 40th parallel. In 2015, approval for release of Spathius galinae Belokobylskij (Hymenoptera: Braconidae), an EAB larval parasitoid from the Russian Far East, may be granted in the United States of America. Researchers are guardedly optimistic that a complex of introduced and native natural enemies will regulate EAB densities below a tolerance threshold for survival of ash species or genotypes in forested ecosystems.


2006 ◽  
Vol 8 (7) ◽  
pp. 1439-1450 ◽  
Author(s):  
Jianqing Ding ◽  
Richard Reardon ◽  
Yun Wu ◽  
Hao Zheng ◽  
Weidong Fu

1996 ◽  
Vol 1 (1) ◽  
pp. 3-24 ◽  
Author(s):  
Alan Rodger

This article is the revised text of the first W A Wilson Memorial Lecture, given in the Playfair Library, Old College, in the University of Edinburgh, on 17 May 1995. It considers various visions of Scots law as a whole, arguing that it is now a system based as much upon case law and precedent as upon principle, and that its departure from the Civilian tradition in the nineteenth century was part of a general European trend. An additional factor shaping the attitudes of Scots lawyers from the later nineteenth century on was a tendency to see themselves as part of a larger Englishspeaking family of lawyers within the British Empire and the United States of America.


Author(s):  
James C Alexander

From the first days, of the first session, of the first Congress of the United States, the Senate was consumed by an issue that would do immense and lasting political harm to the sitting vice president, John Adams. The issue was a seemingly unimportant one: titles. Adams had strong opinions on what constituted a proper title for important officers of government and, either because he was unconcerned or unaware of the damage it would cause, placed himself in the middle of the brewing dispute. Adams hoped the president would be referred to as, “His highness, the President of the United States of America, and Protector of the Rights of the Same.” The suggestion enraged many, amused some, and was supported by few. He lost the fight over titles and made fast enemies with several of the Senators he was constitutionally obligated to preside over. Adams was savaged in the press, derided in the Senate and denounced by one of his oldest and closest friends. Not simply an isolated incident of political tone-deafness, this event set the stage for the campaign against Adams as a monarchist and provided further proof of his being woefully out of touch.


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