Due to increased use of agrochemicals and growing concerns about ecotoxicology, the development of new insecticides, moving away from those with neurotoxic and broad spectrum effects towards insecticides that are safer for the environment and nontarget beneficial species, has been a research priority. Novaluron stands out among these newer insecticides, is an insect growth regulator that is used for the control of insect pests in crops grown close to mulberry plantations. Mulberry serves as food for the silkworm Bombyx mori, which is a nontarget insect of great economic importance to silk production. We investigated the lethal and sublethal effects of Novaluron on the development of B. mori. Larvae were segregated into experimental groups: the control groups (CGs) and the treatment groups (TGs), which were treated with the Novaluron concentration of 0.15 mL/L. Following exposure, we analyzed: larval mortality, changes in the insect life cicle and cytotoxic effects on the midgut cells. This is the first report about the Novaluron’s effects on B.mori. We detected rupture in the integument, complete cessation of feeding, late development, incomplete ecdysis and production of defective cocoons. After 240 h of exposure, there was 100% mortality in TG larvae exposed in the 3rd instar and 20% mortality from larvae exposed in the 5th instar. Cytotoxic effects was observed, such as dilation of cells, emission of cytoplasmic protrusions, extreme rarefaction of the cytoplasm and nuclei, dilation of the endoplasmic reticulum in addition to changes in mitochondria, the presence of large digestive vacuoles and intercellular spaces and the presence of active caspase. Novaluron exposure impairs the midgut and may affect the physiological functions of this organ. Novaluron additionally compromises several phases of insect development, indicating the importance of toxicology studies that utilize different life stages of nontarget species to evaluate the safe use of insecticides.

Plant essential oils are regarded as interesting alternative tools to be integrated into the management of pest insects. However, as they generally consist of mixtures of numerous molecules, the physiological basis for their action is unresolved. Here, we evaluated the effects of essential oil of the Neotropical plant Siparuna guianensis Aubl., commonly known as Negramina, against an important pest insect: the green peach aphid Myzus persicae (Sulzer), and also in two non-target natural enemies: the ladybeetle predators Coleomegilla maculata (DeGeer) and Eriopis connexa (Germar). In addition, we conducted a computational docking analysis for predicting the physical interactions between the two Negramina essential oil major constituents: β-myrcene and 2-undocanone, and the transient receptor potential (TRP) channels as potential binding receptors in the aphid and ladybeetles. As the most important results, Negramina essential oil caused mortality in M. persicae aphids with an LC95 = 1.08 mg/cm2, and also significantly repelled the aphids at concentrations as low as 0.14 mg/cm2. Our computational docking analysis reinforced such selectivity actions as the Negramina essential oil major compounds (i.e., β-myrcene and 2-undocanone) bound to the TRP channels of M. persicae but not to ladybeetle-related TRP channels. Interestingly, the exposure to the Negramina essential oil did not affect the predatory abilities of C. maculata but increased the abilities of E. connexa to prey upon M. persicae. Collectively, our findings provided a physiological basis for the insecticidal and selectivity potential of Negramina essential oil, reinforcing its potential as a tool to be used in integrated pest control programs.

Thiamethoxam is a neonicotinoid insecticide used widely in agriculture to control a broad spectrum of insect pests. To assess potential risks from this compound to non-target aquatic organisms, an outdoor mesocosm study was performed. Mesocosms (1300 L) were treated once with a formulated product with the active substance (a.s.) thiamethoxam at nominal concentrations of 1 (n = 3), 3 (n = 3), 10 (n = 4), 30 (n = 4), and 100 (n = 2) μg a.s./L, plus untreated controls (n = 4). Primary producers (phytoplankton), zooplankton, and macroinvertebrates were monitored for up to 93 days following treatment. Thiamethoxam was observed to have a water column dissipation half-life (DT50) of ≤1.6–5.2 days in the mesocosms. Community-based principal response curve analysis detected no treatment effects for phytoplankton, zooplankton, emergent insects, and macroinvertebrates, indicating a lack of direct and indirect effects. A number of statistically significant differences from controls were detected for individual phytoplankton and zooplankton species abundances, but these were not considered to be treatment-related due to their transient nature and lack of concentration-response. After application of 30 μg a.s./L, slight temporary effects on Asellus aquaticus could not be excluded. At 100 μg a.s./L, there was an effect with no clear recovery of Asellus observed, likely due to their inability to recolonize these isolated test systems. A statistically significant but transient reduction in the emergence of chironomids by day 23 at the 100 μg a.s./L treatment was observed and possibly related to direct toxicity from thiamethoxam on larval stages. Therefore, a conservative study specific No Observed Ecological Adverse Effect Concentration (NOEAEC) is proposed to be 30 μg a.s./L. Overall, based on current concentrations of thiamethoxam detected in North American surface waters (typically <0.4 μg/L), there is low likelihood of direct or indirect effects from a pulsed exposure on primary producers, zooplankton, and macroinvertebrates, including insects, as monitored in this study.

To evaluate plant and herbivore responses to nitrogen we conducted a fertilization study at a low and high pollution site in the mixed conifer forests surrounding Los Angeles, California. Contrary to expectations, discriminant function analysis of oak herbivore communities showed significant response to N fertilization when atmospheric deposition was high, but not when atmospheric deposition was low. We hypothesize that longer-term fertilization treatments are needed at the low pollution site before foliar N nutrition increases sufficiently to affect herbivore communities. At the high pollution site, fertilization was also associated with increased catkin production and higher densities of a byturid beetle that feeds on the catkins of oak. Leaf nitrogen and nitrate were significantly higher at the high pollution site compared to the low pollution site. Foliar nitrate concentrations were positively correlated with abundance of sucking insects, leafrollers and plutellids in all three years of the study.

Thirty Atriplex lines were examined for potential habitat improvement and phytoremediation of selenium (Se) contaminated sites. Studies were conducted to determine the biomass production, Se accumulation, and resistance of each line to the beet armyworm, Spodoptera exigua, an agriculturally important insect. Plants were tested using three salinity treatments: (1) control, no Se; (2) NaCl and CaCl2 salts and 1 mg l-1 Se (12.7 μM) added as sodium selenate; and (3) iso-osmotic to treatment 2 containing high concentrations of sulfate and 1 mg l-1 Se added as sodium selenate. Insect bioassays measured survival, growth, and development. Atriplex patula, A. spongiosa 415862, A. hortensis, A. hortensis 379088 and A. hortensis 379092 were among the top biomass producers and Se accumulators, yet they exhibited significantly reduced insect growth, development, and survival. High background sulfate strongly reduced Se accumulation, suggesting that phytoremediation potential is greatest in saline areas having low to moderate sulfate levels. However, these lines grew well in high salinity soils, indicating possible use as a self-seeding cover crop to improve habitat. All plant lines grown in control and high sulfate salinity treatments are acceptable oviposition sites for S. exigua, indicating that these plants would help reduce populations of this key agricultural pest.

Plants can respond physiologically to damaging ultraviolet-B radiation by altering leaf chemistry, especially UV absorbing phenolic compounds. However, the effects on terpene emissions have received little attention. We conducted two field trials in plots with supplemented UV-B radiation and assessed the influence of feeding by pine weevils, Hylobius abietis L., on volatile emissions from 3-year old Norway spruce trees (Picea abies L. Karst.). We collected emissions from branch tips distal to the feeding weevils, and from whole branches including the damage sites. Weevil feeding clearly induced the emission of monoterpenes and sesquiterpenes, particularly linalool and (E)-β-farnesene, from branch tips, and the sums of monoterpenes and sesquiterpenes emitted by whole branches were substantially increased. We discovered little effect of UV-B radiation up to 30% above the ambient level on volatile emissions from branch tips distal to damage sites, but there was a possible effect on bark emissions from damage sites. Chronic exposure to enhanced UV-B radiation has little effect on volatile emissions of Norway spruce.

Sustained cultivation of Bacillus thuringiensis (Bt) transgenic crops requires stable transgene expression under variable abiotic conditions. We studied the interactions of Bt toxin production and chronic ozone exposure in Bt cry1Ac-transgenic oilseed rape and found that the insect resistance trait is robust under ozone elevations. Bt Cry1Ac concentrations were higher in the leaves of Bt oilseed rape grown under elevated ozone compared to control treatment, measured either per leaf fresh weight or per total soluble protein of leaves. The mean relative growth rate of a Bt target herbivore, Plutella xylostella L. larvae was negative on Bt plants in all ozone treatments. On the non-transgenic plants, larval feeding damage was reduced under elevated ozone. Our results indicate the need for monitoring fluctuations in Bt toxin concentrations to reveal the potential of ozone exposure for altering dosing of Bt proteins to target and non-target herbivores in field environments experiencing increasing ozone pollution. Elevated atmospheric ozone can induce fluctuations in insecticidal protein concentrations in transgenic plants.

Some of the greatest forest health impacts in North America are caused by invasive forest insects and pathogens (e.g., emerald ash borer and sudden oak death in the US), by severe outbreaks of native pests (e.g., mountain pine beetle in Canada), and fires exacerbated by changing climate. Ozone and N and S pollutants continue to impact the health of forests in several regions of North America. Long-term monitoring of forest health indicators has facilitated the assessment of forest health and sustainability in North America. By linking a nationwide network of forest health plots with the more extensive forest inventory, forest health experts in the US have evaluated current trends for major forest health indicators and developed assessments of future risks. Canada and Mexico currently lack nationwide networks of forest health plots. Development and expansion of these networks is critical to effective assessment of future forest health impacts.

Berkheya coddii Roessler (Asteraceae) is a hyper-accumulator of nickel, which can be used in phytomining and phytoremediation. Chrysolina pardalina Fabricius (Chrysomelidae) is a phytophagous leaf beetle, which may be useful in controlling population levels of B. coddii after it has been introduced into a new habitat. The aim of this study was to investigate the response of C. pardalina to topical application of dimethoate. Data recorded included the activity of acetylcholinesterase (AChE), the concentration of glutathione (GSH), and the activity of selected enzymes connected with GSH metabolism. Assays were carried out several times during the first 24 h after exposure to dimethoate. At the dosages used in this study, dimethoate was not as toxic as expected. AChE activity was significantly decreased 14 and 24 h after application. GST activity was significantly decreased 24 h after application. GSTPx activity was significantly decreased 2, 14 and 24 h after application. GR activity was significantly increased 4 h after application. GSH concentration was significantly increased 24 h after application. Long-term exposure to high levels of nickel may have caused adaptive changes in the enzymes that enable C. pardalina to deal with other stressors, including organophosphate pesticides. Long-term exposure to high levels of nickel may have caused adaptive changes in the enzymes that enable Chrysolina pardalina to deal with other stressors, including organophosphate pesticides.

Visible symptoms in tree foliage can be used for stress diagnosis once validated with microscopical analyses. This paper reviews and illustrates macroscopical and microscopical markers of stress with a biotic (bacteria, fungi, insects) or abiotic (frost, drought, mineral deficiency, heavy metal pollution in the soil, acidic deposition and ozone) origin helpful for the validation of symptoms in broadleaved and conifer trees. Differentiation of changes in the leaf or needle physiology, through ageing, senescence, accelerated cell senescence, programmed cell death and oxidative stress, provides additional clues raising diagnosis efficiency, especially in combination with information about the target of the stress agent at the tree, leaf/needle, tissue, cell and ultrastructural level. Given the increasing stress in a changing environment, this review discusses how integrated diagnostic approaches lead to better causal analysis to be applied for specific monitoring of stress factors affecting forest ecosystems. Macroscopic leaf symptoms and their microscopic analysis as stress bioindications.