This paper briefly presents the aims, requirements and results of partial least squares regression analysis (PLSR), and its potential utility in ecological studies. This statistical technique is particularly well suited to analyzing a large array of related predictor variables (i.e. not truly independent), with a sample size not large enough compared to the number of independent variables, and in cases in which an attempt is made to approach complex phenomena or syndromes that must be defined as a combination of several variables obtained independently. A simulation experiment is carried out to compare this technique with multiple regression (MR) and with a combination of principal component analysis and multiple regression (PCA+MR), varying the number of predictor variables and sample sizes. PLSR models explained a similar amount of variance to those results obtained by MR and PCA+MR. However, PLSR was more reliable than other techniques when identifying relevant variables and their magnitudes of influence, especially in cases of small sample size and low tolerance. Finally, we present one example of PLSR to illustrate its application and interpretation in ecology.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0706.2008.16881.x

Partial least squares regression as an alternative to current regression methods used in ecology

Wild boar are now present on all continents except Antarctica and can greatly affect community structure and ecosystem function. Their destructive feeding habits, primarily rooting disturbance, can reduce plant cover, diversity, and regeneration. Furthermore, predation and habitat destruction by boar can greatly affect animal communities. Effects of wild boar on fungi and aquatic communities are scarcely studied, and soil properties and processes seem more resistant to disturbance. Wild boar also affect humans’ economy as they cause crop damage and transmit diseases to livestock and wildlife. In this review, we found that most of the published literature examines boar effects in their introduced range and little is available from the native distribution. Because most of the research describes direct effects of wild boar on plant communities and predation on some animal communities, less is known about indirect effects on ecosystem function. Finally, predictive research and information on ecosystem recovery after wild boar removal are scarce. We identified research gaps and urge the need to lower wild boar densities. Identifying commonalities among wild boar impacts on native ecosystems across its introduced range will help in the design of management strategies.

Impact of wild boar (Sus scrofa) in its introduced and native range: a review

For many leaf-feeding herbivores, synchrony in phenology with their host plant is crucial as development outside a narrow phenological time window has severe fitness consequences. In this review, we link mechanisms, adaptation, and population dynamics within a single conceptual framework, needed for a full understanding of the causes and consequences of this synchrony. The physiological mechanisms underlying herbivore and plant phenology are affected by environmental cues, such as photoperiod and temperature, although not necessarily in the same way. That these different mechanisms lead to synchrony, even if there is spatial and temporal variation in plant phenology, is a result of the strong natural selection acting on the mechanism underlying herbivore phenology. Synchrony has a major impact on the population densities of leaf-feeding Lepidoptera, and years with a high synchrony may lead to outbreaks. Global climate change leads to a disruption of the synchrony between herbivores and their host plants, which may have major impacts for population viability if natural selection is insufficient to restore synchrony.

Phenology of forest caterpillars and their host trees: the importance of synchrony.

Climate Change and Agriculture in the United States: Effects and Adaptation

https://www.fs.fed.us/rm/pubs_other/rmrs_2012_regniere_j001.pdf

Effects of temperature on development, survival and reproduction of insects: experimental design, data analysis and modeling.

The effect of spraying speed (5, 8.5 or 12 km/h) on deposition quality of fungicide on a winter wheat head, yield, grain quality, occurrence of Fusarium head blight (FHB) and deoxynivalenol (DON) content in grains was investigated in 2011 and 2012. Asymmetric double flat fan air-injector nozzles were used in the trial at a spraying pressure of 5.0 bars. A prothiconazole + tebuconazole fungicide mixture was used for spraying. An increase of spraying speed significantly lowered coverage values at the front and rear parts of a wheat head. At all three spraying speeds, the rear part of a wheat head reached a better coverage value. The effect of spraying speed was significant in 2011, when the 5 km/h spraying speed generated a significantly higher grain yield and a significantly higher thousand-grain weight in comparison with the other treatments. In both trial years, the lowest grain yield occurred on the unsprayed control. In 2011 and 2012, the latter also reached the lowest hectolitre weight and thousand-grain weight. In both trial years, the unsprayed control had a significantly higher DONcontent than the other treatments. In 2012, the DONcontent on the unsprayed control exceeded the allowed maximum level. The spraying speed did not affect the DON content in the grains. The effect of spraying speed was also noted in the FHB incidence. A significantly lower FHB incidence occurred at the 5 and 8.5 km/h spraying speeds.

/pdf/effect-of-spraying-speed-on-head-coverage-of-winter-wheat-5amcjdxqat.pdf

Effect of spraying speed on head coverage of winter wheat with fungicide, occurrence of Fusarium head blight and deoxynivalenol, yield and grain quality

In 2007 and 2008 the field experiment was conducted to test the efficacy of three environmentally friendly insecticides against the Colorado potato beetle (Leptinotarsa decemlineata), with the aim of evaluating their effect on the yield of potato. 0.25 % water emulsion of Neem-Azal (active ingredient azadirachtin) was applied twice, while 3 % water emulsion of Aktiv (a.i. potassium salt of fatty acids) and 1 % water emulsion of Prima (a.i. refined rape oil) were applied eight times. In 2007, the potato yield was higher (25.3±3.2 t ha-1) than in 2008 (8.2 ± 0.8 t ha-1). In 2007 there were no significant differences in potato yield at different control measures and the yield ranged from 7.5 ± 1.3 t ha-1 (Aktiv) to 9.4 ± 1.8 t ha-1 (Prima). In 2008, the highest potato yield was recorded in Neem-Azal treatment (3.5 ± 0.7 t ha-1), while in two other insecticide treatments the potato yield did not differ significantly with control treatment neither with the Neem-Azal treatment. Potato tubers were classified into three fractions: fraction 1 (tubers 5 cm). On average we produce 2.11 ± 0.06 t ha-1, 9.93 ± 0.53 t ha-1, and 13.17 ± 0.70 t ha-1 of potato in 2007, and 2.11 ± 0.20 t ha-1, 4.68 ± 0.37 t ha-1, 0.84 ± 0.29 t ha-1 of potato in 2008, respectivelly.

/pdf/field-testing-of-efficacy-of-three-environmentally-friendly-498b7b7fyn.pdf

Field Testing of Efficacy of Three Environmentally Friendly Insecticides Against Colorado Potato Beetle (Leptinotarsa Decemlineata [Say], Coleoptera, Chrysomelidae) on Potato-Evaluation of the Effect on Yield

The chapter presents previous field and laboratory investigations of cabbage flea beetles (Phyllotreta spp.) and cabbage stink bugs (Eurydema spp.) interactions with different Bras‐ sica crops in Slovenia. The special emphasis is given to an influence of different glucosi‐ nolates on injuries caused by mentioned economically important two genera of insect pests. In the study, we found out that the content of glucosinolates differs between differ‐ ent Brassica species, as well as between individual plant organs of the same species. The content of glucosinolates is conditioned also by environmental influences. Among the an‐ alysed glucosinolates, glucobrassicin was presented in all plant species. In almost all plant species, it inhibited the feeding of cabbage flea beetles, except in oil rape, where it had stimulative effects. We have established that the influence of individual glucosinolate on Phyllotreta spp. and Eurydema spp. is not identical as it differs between individual plant species. Because of the variability of glucosinolates as well as different preferences of the studied groups of harmful pests in regard to the plant species, one of the options for diminishing the damage caused by cabbage stink bugs and cabbage flea beetles is the use of mixed Brassica crops for trapping the pests in the growing season. In the future, glucosinolates should be employed to a greater extent in environmentally acceptable ways of food production, one of which is also the use of trap crops in order to reduce harmful effects of cabbage stink bugs.

/pdf/about-previous-investigations-regarding-the-role-of-2460fadk3c.pdf

About Previous Investigations Regarding the Role of Glucosinolates in Controlling Brassica Insect Pests in Slovenia

The wood ash from seven plant species (sessile oak, European beech, European hornbeam, silver fir, European spruce, common alder, and Spanish chestnut) was tested against Spanish slug (Arion vulgaris) as an environmentally acceptable alternative to chemical bait pellets. We carried out laboratory and semi-field experiments to assess the contact and barrier efficacy of selected wood ash. To demonstrate the contact efficacy, slugs were rolled in the wood ash. Geochemical analysis of wood ash was carried out as well. The highest concentrations of chemical compounds SiO2, Al2O3, Fe2O3, MgO and MnO and elements Ba, Co, Cs, Ga, Cu, Pb and Zn were identified in the most effective ashes (beech, oak, fir, and spruce) compared to the ineffective ashes (hornbeam, chestnut, black ader). The concentration of cobalt was comparably higher, while the concentration of molybdenum was comparably lower in the four most effective wood ashes. The results of our studies revealed that the wood ash of oak and spruce have great contact efficacy. The oak and beech wood ash showed the strongest barrier efficacy against slugs. In the semi-field trials, only 10% of the plants treated with oak wood ash were damaged by slugs. The oak wood ash is an efficient alternative for slug control, however, further studies and biotechnical enhancement are needed.

https://www.mdpi.com/2076-3417/10/23/8564/pdf

Contact Efficacy of Different Wood Ashes against Spanish Slug, Arion vulgaris (Gastropoda: Arionidae)

/pdf/possibilities-of-walnuts-juglans-spp-protection-against-3kgjppgcj4.pdf

Stanislav Trdan

Papers

Effect of spraying speed on head coverage of winter wheat with fungicide, occurrence of Fusarium head blight and deoxynivalenol, yield and grain quality

Field Testing of Efficacy of Three Environmentally Friendly Insecticides Against Colorado Potato Beetle (Leptinotarsa Decemlineata [Say], Coleoptera, Chrysomelidae) on Potato-Evaluation of the Effect on Yield

About Previous Investigations Regarding the Role of Glucosinolates in Controlling Brassica Insect Pests in Slovenia

Contact Efficacy of Different Wood Ashes against Spanish Slug, Arion vulgaris (Gastropoda: Arionidae)

Possibilities of Walnuts (Juglans Spp.) Protection Against Walnut Husk Fly (Rhagoletis Completa Cresson) with Special Emphasis on Biological Control