Integrating Flea Beetles (Aphthonaspp.) with Herbicide and Grasses for Leafy Spurge (Euphorbia Esula) Management

2008 ◽  
Vol 22 (3) ◽  
pp. 523-529 ◽  
Author(s):  
Ankush Joshi

Most management tactics used against leafy spurge are not economical, practical, or efficacious when used alone. Combinations of the biological control agent,Aphthonabeetles, the herbicide imazapic (105 g/ha), and interseeded native grass species were evaluated for leafy spurge management at two sites: Sheyenne National Grassland and Ekre Grassland Preserve in North Dakota during 2001 to 2005. At the Sheyenne site, over a 5-yr study period, leafy spurge was reestablishing its stem density after a single application of imazapic, but stand suppression was maintained to < 11 stems/m2when management combined imazapic withAphthonaor interseeding of native grasses.Aphthonabeetles established at the Sheyenne site, but declined as leafy spurge density decreased. However, the remainingAphthonapopulation continued to suppress leafy spurge density. Leafy spurge stem control was successfully maintained for 3 yr byAphthonaand grass competition without repetition of the imazapic treatment. Leafy spurge root dry weights were reduced by 66% (< 111g/m2) in the insect plots during this period. At the Ekre site, similar results were observed for the first 3 yr. However, in the fourth yr, a failure of biological control agents to establish resulted in the resurgence of leafy spurge. During this study, lowerAphthonaemergence was observed in imazapic-treated plots, possibly due to reduced leafy spurge density.

2017 ◽  
Vol 10 (2) ◽  
pp. 180-190 ◽  
Author(s):  
Blake M. Thilmony ◽  
Rodney G. Lym

Aphthona spp. flea beetles were released in two ecological sites of the Little Missouri National Grasslands in southwestern North Dakota in 1999 to control leafy spurge. The change in leafy spurge density and soil seedbank composition was monitored to evaluate the effectiveness of the biological weed control agent and the associated change in plant communities 5, 10, and 15 yr after release in loamy overflow (valleys) and loamy sites (ridges). In 2014, 15 yr after release, leafy spurge stem density had decreased 94% from 110 to 7 stems m−2 in the loamy overflow sites and 88% from 78 to 9 stems m−2 in the loamy sites. Leafy spurge represented only 2% and 6% of the loamy overflow and loamy seedbanks in 2004, respectively, compared with nearly 67% and 70%, respectively, in 1999. There was a slow shift to reintroduction of native species into the seedbank over the last 15 yr. The number of desirable species increased to 21 by 2014 (more than three times the number of species in 1999) in the loamy overflow sites, and doubled to 14 species in the loamy sites, while less desirable forb species doubled in both sites. Desirable grass species doubled in the loamy overflow sites by 2014 but remained unchanged in loamy sites. Aphthona spp. successfully controlled leafy spurge for more than 15 yr without any additional control methods or costs to land managers and resulted in the slow return of a subset of native species.


Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 86-88 ◽  
Author(s):  
Joseph M. Krupinsky ◽  
Russell J. Lorenz

In 1979 and 1980, isolates ofAlternariawere obtained from diseased leafy spurge (Euphorbia esulaL.) plants. The pathogenicity of anAlternariasp. towards leafy spurge was demonstrated in glasshouse and limited field studies, and theAlternariais considered to be a potential biological - control agent for leafy spurge. The pathogenicity and cultural characteristics of the fungus suggest its classification asA. tenuissimaf. sp.euphorbiae,with isolate Krupinsky 80-3547ss4 (= E. G. Simmons 35-079) as a representative strain.


2011 ◽  
Vol 4 (2) ◽  
pp. 183-188 ◽  
Author(s):  
Robert A. Progar ◽  
George Markin ◽  
Joseph Milan ◽  
Tom Barbouletos ◽  
Matthew J. Rinella

AbstractWe evaluated the efficacy of the biological control agent, red-headed leafy spurge stem borer, against the nonnative invasive plant leafy spurge. Our three treatments were release of the biological control agent into uncaged plots, release of the biological control agent into plots caged to prevent agent escape, and control plots caged to prevent agent entry. These treatments were replicated three times at six sites in the western United States. We measured leafy spurge biomass for 1 or 2 yr following release. We also measured the percentage of leafy spurge stems showing evidence of red-headed leafy spurge stem borer oviposition for either 1 or 2 yr following agent release, depending on the site. Red-headed leafy spurge stem borer did not demonstrably reduce leafy spurge biomass in our study. Moreover, compared to the release year, evidence of red-headed leafy spurge stem borer oviposition declined with time, suggesting the agent population was diminishing. This suggests the agent is incapable of building large populations capable of controlling leafy spurge at the sites we studied. However, after being released, populations of biological control agents sometimes go through long lag phases and then begin rapid population increases, so we cannot completely dismiss the possibility that red-headed leafy spurge stem borer might become effective given more time.


Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 348-352 ◽  
Author(s):  
Barbara K. Landgraf ◽  
Peter K. Fay ◽  
Kris M. Havstad

The forage selection and grazing behavior of sheep in leafy spurge (Euphorbia esula L. ♯3 EPHES)-infested pastures was examined in a 3-month grazing study conducted during the summer, 1981. No definite preference for or avoidance of leafy spurge was detected. An initial 1- to 3-week avoidance was observed, followed by a steady increase in leafy spurge consumption. A maximum intake of 40 to 50% of the diet per animal was observed. Weight gain by ewes in pastures infested with leafy spurge was not significantly different from weight gain by ewes in pastures free of leafy spurge. Results from these studies indicate that leafy spurge may be classified as a forage for sheep. Sheep will consume a significant amount of vegetation while suffering neither harmful internal effects nor a significant loss of body weight. Sheep can be considered an effective biological control agent for leafy spurge.


Weed Science ◽  
1980 ◽  
Vol 28 (3) ◽  
pp. 235-240 ◽  
Author(s):  
J. R. Forwood ◽  
M. K. McCarty

The feasibility of using the spurge hawkmoth (Hyles euphorbiaeL., Lepidoptera: Sphingidae), as a biological control agent on leafy spurge (Euphorbia esulaL.) was evaluated. Studies relating adult hawkmoth emergence from the pupal stage and spring growth of leafy spurge plants showed that the plants would provide food and oviposition sites for the insect. Two generations of the insect may occur each year. Winter temperatures at approximately 2.5 cm below the soil surface or in the litter would result in some mortality of hawkmoth pupae. Pupal release programs indicated that protection from insect and rodent predators was necessary for adult emergence to occur. Predator determination using32P indicated two specimens ofCalosoma calidumFab. and two specimens ofFormica subsericeaSay as possible predators. Predator determination using pitfall traps showed that several species listed by Canadian researchers as predators were present in leafy spurge stands in Nebraska. At this time it appears the spurge hawkmoth will not become a valuable biological control agent for leafy spurge in Nebraska.


2008 ◽  
Vol 1 (1) ◽  
pp. 26-30 ◽  
Author(s):  
John L. Baker ◽  
Nancy A. P. Webber

AbstractThe biological control agent Aphthona nigriscutis Foudras (Chrysomelidae) established in Fremont County, WY since 1992 on leafy spurge was released into a mixed stand a native plant Euphorbia robusta Engelm. During host range testing, E. robusta was a likely host for A. nigriscutis under laboratory conditions. In 1999, A. nigriscutis was observed feeding on both E. esula and 31 of 36 E. robusta plants present on about 2 ha (5 ac) where the visually estimated E. esula canopy cover was 50%. By August 2001, E. esula cover had declined to less than 5% and E. robusta plants had increased to 450 plants with 26 (5.8%) showing feeding damage. In 2006 Euphorbia esula ground cover was 2% and of 598 E. robusta plants originally marked, 391 could be located and four of these had damage consistent with A. nigriscutis feeding. For the 8-yr period, E. esula ground cover was inversely correlated to E. robusta density and positively correlated to A. nigriscutis feeding damage on E. robusta. This study shows that while also acceptable to A. nigriscutis in the field, feeding on E. robusta declined with declining densities of the target weed while E. robusta population densities increased. It seems that some risk in this regard is acceptable in light of the damage from the target weed and the generally high level of selectivity provided by biological control agents.


2011 ◽  
Vol 101 (1) ◽  
pp. 113-123 ◽  
Author(s):  
V. O. Stockwell ◽  
K. B. Johnson ◽  
D. Sugar ◽  
J. E. Loper

Mixtures of biological control agents can be superior to individual agents in suppressing plant disease, providing enhanced efficacy and reliability from field to field relative to single biocontrol strains. Nonetheless, the efficacy of combinations of Pseudomonas fluorescens A506, a commercial biological control agent for fire blight of pear, and Pantoea vagans strain C9-1 or Pantoea agglomerans strain Eh252 rarely exceeds that of individual strains. A506 suppresses growth of the pathogen on floral colonization and infection sites through preemptive exclusion. C9-1 and Eh252 produce peptide antibiotics that contribute to disease control. In culture, A506 produces an extracellular protease that degrades the peptide antibiotics of C9-1 and Eh252. We hypothesized that strain A506 diminishes the biological control activity of C9-1 and Eh252, thereby reducing the efficacy of biocontrol mixtures. This hypothesis was tested in five replicated field trials comparing biological control of fire blight using strain A506 and A506 aprX::Tn5, an extracellular protease-deficient mutant, as individuals and combined with C9-1 or Eh252. On average, mixtures containing A506 aprX::Tn5 were superior to those containing the wild-type strain, confirming that the extracellular protease of A506 diminished the biological control activity of C9-1 and Eh252 in situ. Mixtures of A506 aprX::Tn5 and C9-1 or Eh252 were superior to oxytetracycline or single biocontrol strains in suppressing fire blight of pear. These experiments demonstrate that certain biological control agents are mechanistically incompatible, in that one strain interferes with the mechanism by which a second strain suppresses plant disease. Mixtures composed of mechanistically compatible strains of biological control agents can suppress disease more effectively than individual biological control agents.


Weed Science ◽  
1986 ◽  
Vol 34 (S1) ◽  
pp. 33-34 ◽  
Author(s):  
Paul E. Parker

The use of nematodes as biological control agents has been met with skepticism, partly due to the newness of the approach and also to the potential difficulties of using a parasitic worm as a control organism. Most of the attention directed towards nematodes as biological control agents has been focused on several species that act as insect parasites. Considerable headway has been achieved with several of these parasites, especially with those parasitic on wood-boring insect larvae. The insect gallery of wood-boring larvae provides an optimum microclimate for the nematode to survive and seek out its larval insect host. A system where this strategy has proved successful involves the use of the insect parasitic nematodeNeoaplectana carpocapsaeWeiser as a biological control agent for carpenterworms (Prionoxystus robinaePeck) in fig (Ficus cariaL.) orchards in California (6). Similar systems are being developed both here and abroad with the same nematode or a closely related genus or species. Many of these systems show promise (5).


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