Specialized soil types affect host acceptability and performance of weed biocontrol candidates: implications for host specificity assessments

This paper presents information on the selection and performance of anchors for guyed EHV transmission towers. The information used was obtained during the design and construction of two transmission lines each over 540 miles (>869 km) long in British Columbia.Five anchors have been designed and tested: (1) buried plate with compacted backfill; (2) buried steel mat or grillage with loose backfill; (3) cast-in-place concrete with loose backfill; (4) power installed helical; and (5) grouted rod anchors.The highly variable soil and access conditions along the line necessitated an anchor that could economically be installed in nearly all soil types and by ordinary construction equipment that could easily move between tower sites in rugged terrain.The simply installed, conservatively designed, cast-in-place concrete anchor was found to satisfy these requirements at reasonable cost. Power-installed helical anchors and grouted rod anchors may provide an economical anchor in more uniform soil conditions and where easier access conditions exist. However, these anchors require more detailed soil exploration and contract inspection than the cast-in-place concrete anchors.

Download Full-text

Preference Provides a Plethora of Problems (Don't Panic)

Annual Review of Entomology ◽

10.1146/annurev-ento-022720-061725 ◽

2021 ◽

Vol 66 (1) ◽

pp. 1-22

Author(s):

Michael C. Singer

Keyword(s):

Experimental Designs ◽

Testing Technique ◽

Preference Testing ◽

Plant Insect Interactions ◽

Oviposition Preferences ◽

And Performance ◽

Insect Interactions ◽

Host Acceptability

This review was solicited as an autobiography. The “problems” in my title have two meanings. First, they were professional difficulties caused by my decision to study oviposition preferences of butterflies that were not susceptible to traditional preference-testing designs. Until I provided video, my claim that the butterflies duplicate natural post-alighting host-assessment behavior when placed on hosts by hand was not credible, and the preference-testing technique that I had developed elicited skepticism, anger, and derision. The second meaning of “problems” is scientific. Insect preference comes with complex dimensionality that interacts with host acceptability. Part Two of this review describes how my group's work in this area has revealed unexpected axes of variation in plant–insect interactions—axes capable of frustrating attempts to derive unequivocal conclusions from apparently sensible experimental designs. The possibility that these complexities are lurking should be kept in mind as preference and performance experiments are devised.

Download Full-text

The effects of intraspecific hybridization on the host specificity of a weed biocontrol agent

Biological Control ◽

10.1016/j.biocontrol.2021.104585 ◽

2021 ◽

Vol 157 ◽

pp. 104585

Author(s):

M. Szűcs ◽

E.I. Clark ◽

U. Schaffner ◽

J.L. Littlefield ◽

C. Hoover ◽

...

Keyword(s):

Host Specificity ◽

Biocontrol Agent ◽

Intraspecific Hybridization ◽

Weed Biocontrol

Download Full-text

Identification and Performance of Swelling Soil Types

Canadian Geotechnical Journal ◽

10.1139/t65-018 ◽

1965 ◽

Vol 2 (2) ◽

pp. 141-153 ◽

Cited By ~ 7

Author(s):

R M Hardy

Keyword(s):

Soil Mechanics ◽

Swelling Pressure ◽

Soil Types ◽

Engineering Practice ◽

Swelling Soils ◽

Design Practices ◽

Swelling Soil ◽

Current Design ◽

Swelling Characteristics ◽

And Performance

Many soil types, both overconsolidated and normally consolidated, in the Prairie provinces and northwestern Canada display high swelling characteristics. Experience has shown that conventional theories of soil mechanics are inadequate to predict accurately the performance of such soils in engineering practice. The paper discusses procedures for the identification of highly swelling soils and for numerically evaluating potential swelling pressures. Modifications to current design practices are suggested and the importance of swelling pressure concepts in engineering practice are discussed.

Download Full-text

Determination of biotypes of Dactylopius tomentosus (Hemiptera: Dactylopiidae) and insights into the taxonomic relationships of their hosts, Cylindropuntia spp.

Bulletin of Entomological Research ◽

10.1017/s0007485309990496 ◽

2009 ◽

Vol 100 (3) ◽

pp. 347-358 ◽

Cited By ~ 10

Author(s):

C.W. Mathenge ◽

P. Holford ◽

J.H. Hoffmann ◽

H.G. Zimmermann ◽

R. Spooner-Hart ◽

...

Keyword(s):

Biological Control ◽

Host Specificity ◽

Development Time ◽

Biological Control Agent ◽

Taxonomic Status ◽

Control Agent ◽

Host Specialization ◽

Female Development ◽

Use Patterns ◽

And Performance

AbstractHost specialization to form biotypes is common among phytophagous insects, and it has been hypothesised that biotypes of Dactylopius tomentosus L. (Hemiptera: Dactylopiidae) occur. D. tomentosus is an important biological control agent for Cylindropuntia cacti when they occur as weeds. Additionally, there is uncertainty surrounding the taxonomic status of some species of Cylindropuntia. This study aimed to confirm the existence of D. tomentosus biotypes and to assess whether host specialization can help to resolve this systematic uncertainty. For this study, the host specificity and performance of ten provenances of D. tomentosus collected from C. cholla, C. fulgida var. fulgida, C. imbricata, C. f. var. mamillata, C. rosea and C. tunicata and reared on C. cholla, C. fulgida var. fulgida, C. imbricata and C. rosea were investigated. Five life-history parameters were measured including: crawler development time and survival, female development time, and the weight and number of eggs produced by females. Results revealed significant variation in host specificity with provenances either thriving, surviving or dying on the different hosts, thus demonstrating the existence of biotypes. Also, host specificity was related to host species and not to the geographic locality from which either the host or provenance was sourced. These findings suggest that the characteristics of Cylindropuntia species may differ sufficiently, there by presenting different selection pressures that induce and sustain distinct biotypes of D. tomentosus. The observed host use patterns of the biotypes separated the plant species into two groups that accorded with known phylogenetic relationships among Cylindropuntia species, suggesting that biotypes can be used to elucidate their taxonomic relatedness. Besides advancing our knowledge of the ecology and evolution of D. tomentosus, these novel findings have important implications for the biological control of Cylindropuntia species.

Download Full-text

Discussion: Identification and Performance of Swelling Soil Types

Canadian Geotechnical Journal ◽

10.1139/t66-018 ◽

1966 ◽

Vol 3 (3) ◽

pp. 167-168

Author(s):

T C Kenney

Keyword(s):

Soil Types ◽

Swelling Soil ◽

And Performance

Download Full-text

Simulation and performance yield of soybean and maize crops by AquaCrop, in Campos Gerais, Paraná State

Acta Iguazu ◽

10.48075/actaiguaz.v9i2.23169 ◽

2020 ◽

Vol 9 (2) ◽

pp. 45-58

Author(s):

Jorge Luiz Moretti de Souza ◽

Karla Regina Piekarski ◽

Stefanie Lais Kreutz Rosa ◽

Mariana Vasconcelos Barroca ◽

Rodrigo Yoiti Tsukahara

Keyword(s):

Input Data ◽

Computational Models ◽

Soil Management ◽

Maize Yield ◽

Soil Types ◽

Agricultural Crops ◽

Maize Crop ◽

Aquacrop Model ◽

And Performance ◽

Relative Errors

The computational models that simulate yield of agricultural crops are important to planning activities. The objective of this study was to verify the performance of AquaCrop model to simulate soybean and maize yield in Campos Gerais region, in different soil types. The AquaCrop was used to estimate yield, requiring climate, soil, crop and soil management input data. In the analysis were used data from 21 and 32 experiments with maize and soybeans, respectively, carried out in the ABC Foundation, from years harvest between 2006 and 2014. For soybean crop, the highest absolute and relative errors of productivity simulations occurred in less productive crops, due to the lack of rain during sowing, water deficit in the harvest or high temperatures in the first weeks after the plants emergence. The highest absolute and relative errors verified in the simulations with maize crop experiments did not allow defined pattern identification. The AquaCrop achieved “very good” and “excellent” performances in the simulations of soybean and maize yield it the analyzed locations. The soil type affected the results from the analyzes of the two crops, and the Latossolos provided better performance and higher correlation compared to other soil types.

Download Full-text