Effects of spirotetramat treatments on fecundity and carboxylesterase expression of <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover

Spirotetramat is a novel tetramic acid-based insecticide, belonging to keto-enol pesticide family, with a novel mode of action; it interferes with lipid biosynthesis. Its insecticide activity against various agricultural pest insects have been demonstrated (e.g. on Myzus persicae, Bemisia tabaci and Tetranychus urticae). However, information available is currently limited on the efficacy of spirotetramat on the cotton aphid, Aphis gossypii, a key cotton pest worldwide. We assessed the spirotetramat toxicity on A. gossypii and evaluated its effects on aphid fecundity when exposed to a sublethal concentration (LC₁₀) and to increasing lethal concentrations (LC₂₅, LC₅₀, and LC₇₅). A key mechanism involved in insecticide resistance in aphids relates to esterase activity. We estimated the CarE activity and a CarE gene expression in aphids in response to spirotetramat exposure, then we tested tolerance of offspring to spirotetramat when the parents were exposed to the highest concentration tested in our study (LC₇₅). Results showed that spirotetramat showed increasing toxicity to A. gossypii with exposure duration to treated leaves; LC₅₀ ranged from 23,675.68 to 12.27 mg/L for 1 to 5-days exposure. In addition, spirotetramat reduced aphid daily fecundity, in all concentration treatments, especially with up to 90 % reduction in case of exposure to LC₇₅. Total CarE activity increased dramatically and CarE mRNA expression was also up regulated in aphids after exposure to LC₇₅ spirotetramat. Finally, the tolerance to spirotetramat in offspring (when parents were exposed to the LC₇₅) showed a 2.5-fold increase when compared to control aphids. Consequently, spiroteramat showed potential for pest management of cotton aphids owing to both lethal and sublethal activities, notably strong impact on aphid fecundity. However, we also demonstrated that increased tolerance of A. gossypii to spirotetramat may happen through increased CarE- activity and subsequent metabolic degradation of the insecticide in aphids’ body.     

Sublethal and hormesis effects of beta-cypermethrin on the biology,life table parameters and reproductive potential of soybean aphid <Emphasis Type="Italic">Aphis glycines</Emphasis>

Beta-cypermethrin has long been recommended as an effective pesticide to control the soybean aphid, Aphis glycines Matsumura, a serious pest in soybean crops. Besides acute toxicity, it leads to changes in life history traits of A. glycines, notably its reproductive potential. This study has assessed the effects of five sublethal concentrations (0.625, 1.25, 2.5, 5 and 10?µg/L) of beta-cypermethrin on different life history traits of A. glycines. Exposure to these concentrations caused shorter oviposition period and reduced adult longevity. The strongest stimulatory effect on aphid reproduction was achieved when exposed to a higher sublethal beta-cypermethrin concentration (5?µg/L). Net reproduction rate (R ₀ ), intrinsic rate of increase (r _m ) and finite rate of increase (λ) were significantly higher than that of the control, increasing by 20.58, 4.89 and 2.06%, respectively. We found no significant difference in mean generation time (T) between the treatment of 5?µg/L beta-cypermethrin and the control. However, when the concentration increased to 10?µg/L, the reproduction behavior was restrained and the mean generation time (T) was shortened, resulting in significant decrease in R ₀ and T by 16.58 and 3.83%, respectively. In conclusion, a sublethal concentration (5?µg/L) of beta-cypermethrin triggered the strongest hormesis on A.glycines, thus providing valuable knowledge on the sublethal effects of this insecticide on soybean aphids. Hormesis may be one of the mechanisms underlying pest resurgences, and better knowledge would enable a more effective use of insecticides in Integrated Pest Management programs.     

Sublethal effects of pyrethroid and neonicotinoid insecticides on <Emphasis Type="Italic">Iphiseiodes zuluagai</Emphasis> Denmark and Muma (Mesostigmata: Phytoseiidae)

The predator mite Iphiseiodes zuluagai Denmark & Muma is an important biological-control agent of mite pests, and it is one of the most common species found in citrus orchards. This study assessed, under laboratory conditions, the toxicity and duration of the harmful effects of five insecticides, the three pyrethroids deltamethrin, esfenvalerate and lambda-cyhalothrin, and the two neonicotinoids imidacloprid and thiamethoxam on I. zuluagai. Furthermore, we estimated the life-table parameters of the predator. Our results showed that deltamethrin and lambda-cyhalothrin caused higher mortality of larvae and adults than imidacloprid and thiamethoxam. In contrast, esfenvalerate provided larval mortality similar to imidacloprid and thiamethoxam, but it did not cause significant adult mortality of the predator. Mites that developed on pyrethroid residues showed lower survival of the immature stages, fecundity, and longevity compared to neonicotinoid residues and the control treatment. The estimated life-table parameters indicated that deltamethrin, lambda-cyhalothrin and esfenvalerate caused greater reduction in R _o and r of I. zuluagai compared with imidacloprid and thiamethoxam, which were similar to the control treatment. Besides the impacts on biological and population parameters, the duration of the harmful activity of pyrethroid insecticides was longer than the neonicotinoids. Therefore, the use of pyrethroid insecticides to control pest insects may involve serious implications for integrated pest-management programs that aim to exploit the biological control by I. zuluagai in citrus orchards.     

Risk assessment of various insecticides used for management of Asian citrus psyllid, <Emphasis Type="Italic">Diaphorina citri</Emphasis> in Florida citrus,against honey bee, <Emphasis Type="Italic">Apis mellifera</Emphasis>

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus trees worldwide. A wide variety of insecticides are used to manage D. citri populations within citrus groves in Florida. However, in areas shared by citrus growers and beekeepers the use of insecticides may increase the risks of Apis mellifera  L. (Hymenoptera: Apidae) loss and contaminated honey. The objective of this research was to determine the environmental toxicity of insecticides, spanning five different modes of action used to control D. citri, to A. mellifera. The insecticides investigated were imidacloprid, fenpropathrin, dimethoate, spinetoram and diflubenzuron. In laboratory experiments, LD₅₀ values were determined and ranged from 0.10 to 0.53?ng/μl for imidacloprid, fenpropathrin, dimethoate and spinetoram. LD₅₀ values for diflubenzuron were >1000?ng/μl. Also, a hazard quotient was determined and ranged from 1130.43 to 10893.27 for imidacloprid, fenpropathrin, dimethoate, and spinetoram. This quotient was <0.447 for diflubenzuron. In field experiments, residual activity of fenpropathrin and dimethoate applied to citrus caused significant mortality of A. mellifera 3 and 7 days after application. Spinetoram and imidacloprid were moderately toxic to A. mellifera at the recommended rates for D. citri. Diflubenzuron was not toxic to A. mellifera in the field as compared with untreated control plots. Phenoloxidase (PO) activity of A. mellifera was higher than in untreated controls when A. mellifera were exposed to 14 days old residues. The results indicate that diflubenzuron may be safe to apply in citrus when A. mellifera are foraging, while most insecticides used for management of D. citri in citrus are likely hazardous under various exposure scenarios.     

A sublethal imidacloprid concentration alters foraging and competition behaviour of ants

Neonicotinoid pesticides, such as the widely used compound imidacloprid, are suspected to impair cognitive capacity, behaviour, and fitness of a number of non-target species. We tested whether sublethal imidacloprid concentrations alter the foraging and aggression behaviour of two European ant species. Even though the nestmate-recruitment of Lasius niger was not affected by pesticide exposure, these ants required more time to become active and the number of foraging workers was lower than in sub-colonies not exposed to imidacloprid. In interspecific confrontations, imidacloprid increased the aggressiveness of a usually subordinate species (Lasius flavus) enormously (3.7-fold increase in average number of aggressive encounters), whereas they did not affect a subdominant species (L. niger) that severely (1.2-fold increase in average number of aggressive encounters). The high frequency of aggressive encounters of L. flavus vs. non-exposed L. niger workers, reduced their survival probability significantly down to 60 %. The observed behavioural alterations of the two ant species have the potential to impair their viability and co-occurrence with behaviourally dominate species due to a decreased exploitative competition and a reduced chance to locate and use resources before competitors. As competition is considered key in structuring ant communities, changes in aggressiveness are likely to alter established dominance hierarchies and thereby the dynamic and structure of ant communities.     

Sublethal and transgenerational effects of sulfoxaflor on the biological traits of the cotton aphid, <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover (Hemiptera: Aphididae)

Sulfoxaflor is a novel insecticide belonging to sulfoximine chemical class that can be used to control sap-feeding insects, notably Aphis gossypii Glover. In addition to its acute toxicity, it is also important to consider the possible sublethal effects when establishing a comprehensive understanding of the toxicity of a new insecticide. We assessed the effects of a low lethal concentration (LC₂₅) of sulfoxaflor on biological parameters of A. gossypii adults (F0) and subsequent transgenerational effects, i.e., on the progeny (F1 generation). The data were analyzed using an age-stage life table procedure. The results showed that the longevity and fecundity were not significantly affected by the LC₂₅ of sulfoxaflor in the F0 or F1 generations. In addition, no significant differences were observed on the developmental time of each instar, the adult pre-oviposition period, and on the longevity of F1 individuals. However, the duration of their pre-adult stage and total pre-oviposition period, as well as their mean generation time were significantly increased. These observed effects affected aphid demographic traits; the survival rate, the intrinsic rate of increase (r _i ), the finite rate of increase (λ), the net reproductive rate (R₀), and the gross reproduction rate (GRR) of the F1 individuals (i.e., from F0 mothers) were significantly lower compared to the control. Our results showed that sublethal effects of sulfoxaflor significantly slowed down A. gossypii population growth; they indicated that effects of sulfoxaflor might be increased (beyond lethal effect) through sublethal effects when concentrations decreased in sulfoxaflor-treated areas after initial application in field.     

Impact of insect growth regulators on the predator <Emphasis Type="Italic">Ceraeochrysa cincta</Emphasis> (Schneider) (Neuroptera: Chrysopidae)

The generalist predator Ceraeochrysa cincta (Schneider) (Neuroptera: Chrysopidae) is an important biological control agent of several arthropod pests in different agroecosystems. This study assessed the lethal and sublethal effects of six insect growth regulators sprayed on first-instar larvae of C. cincta. Lufenuron and diflubenzuron were highly harmful to first-instar larvae of C. cincta, causing 100 % of mortality before they reached the second instar. Buprofezin caused ~25 % mortality of the larvae and considerably reduced the fecundity and longevity of the insects, but substantially increased the proportion of females in the surviving population of C. cincta. Methoxyfenozide and tebufenozide did not affect the duration and survival of the immature stages, but methoxyfenozide significantly reduced the fecundity and longevity of the insects. Pyriproxyfen reduced the survival of the larval stage by 19.5 %, but did not affect the development, survival and reproduction of the surviving individuals. Based on reduction coefficient, the insecticides diflubenzuron and lufenuron were considered harmful to C. cincta, whereas buprofezin and methoxyfenozide were slightly harmful and tebufenozide and pyriproxyfen were harmless. The estimation of life-table parameters indicated that buprofezin and methoxyfenozide significantly reduced the R _o , r and λ of C. cincta, whereas pyriproxyfen and tebufenozide caused no adverse effect on population parameters, indicating that these insecticides could be suitable for use in pest management programs towards the conservation and population increase of the predator in agroecosystems. However, more studies should be conducted to evaluate the compatibility of these insecticides with the predator C. cincta under semi-field and field conditions.     

Comparative toxicity of imidacloprid and thiacloprid to different species of soil invertebrates

Neonicotinoid insecticides have come under increasing scrutiny for their impact on non-target organisms, especially pollinators. The current scientific literature is mainly focused on the impact of these insecticides on pollinators and some aquatic insects, leaving a knowledge gap concerning soil invertebrates. This study aimed at filling this gap, by determining the toxicity of imidacloprid and thiacloprid to five species of soil invertebrates: earthworms (Eisenia andrei), enchytraeids (Enchytraeus crypticus), Collembola (Folsomia candida), oribatid mites (Oppia nitens) and isopods (Porcellio scaber). Tests focused on survival and reproduction or growth, after 3–5 weeks exposure in natural LUFA 2.2 standard soil. Imidacloprid was more toxic than thiacloprid for all species tested. F. candida and E. andrei were the most sensitive species, with LC₅₀s of 0.20–0.62 and 0.77?mg/kg dry soil for imidacloprid and 2.7–3.9 and 7.1?mg/kg dry soil for thiacloprid. EC₅₀s for effects on the reproduction of F. candida and E. andrei were 0.097–0.30 and 0.39?mg/kg dry soil for imidacloprid and 1.7–2.4 and 0.44?mg/kg dry soil for thiacloprid. The least sensitive species were O. nitens and P. scaber. Enchytraeids were a factor of 5–40 less sensitive than the taxonomically related earthworm, depending on the endpoint considered. Although not all the species showed high sensitivity to the neonicotinoids tested, these results raise awareness about the effects these insecticides can have on non-target soil invertebrates.     

Individual and combined toxic effects of herbicide atrazine and three insecticides on the earthworm, <Emphasis Type="Italic">Eisenia fetida</Emphasis>

In the present study, we evaluated the individual and combined toxic effects of herbicide atrazine and three insecticides (chlorpyrifos, lambda-cyhalothrin and imidacloprid) on the earthworm, Eisenia fetida. Results from 48-h filter paper test indicated that imidacloprid had the highest toxicity to E. fetida with an LC₅₀ of 0.05 (0.041–0.058) μg a.i. cm^?2, followed by lambda-cyhalothrin and atrazine with LC₅₀ values ranging from 4.89 (3.52–6.38) to 4.93 (3.76–6.35) μg a.i. cm^?2, while chlorpyrifos had the least toxicity to the worms with an LC₅₀ of 31.18 (16.22–52.85) μg a.i. cm^?2. Results from 14-days soil toxicity test showed a different pattern of toxicity except that imidacloprid was the most toxic even under the soil toxicity bioassay system. The acute toxicity of atrazine was significantly higher than that of chlorpyrifos. In contrast, lambda-cyhalothrin was the least toxic to the animals under the soil toxicity bioassay system. The binary mixture of atrazine–lambda-cyhalothrin and ternary mixture of atrazine–chlorpyrifos–lambda-cyhalothrin displayed a significant synergistic effect on the earthworms under the soil toxicity bioassay. Our findings would help regulatory authorities understand the complexity of effects from pesticide mixtures on non-target organisms and provide useful information of the interaction of various pesticide classes detected in natural environment.     

Bt<Subscript>i</Subscript>-based insecticide enhances the predatory abilities of the backswimmer <Emphasis Type="Italic">Buenoa tarsalis</Emphasis> (Hemiptera: Notonectidae)

The backswimmer Buenoa tarsalis (Hemiptera: Notonectidae) is a naturally occurring predator of immature stages of mosquitoes. These aquatic predators can suffer from non-targeted exposure to insecticides that are commonly used in aquatic environments to control mosquitoes. Here, we evaluated whether insecticide formulations containing the bacterium Bacillus thuringiensis var. israelensis (Bt_i) or the organophosphate pirimiphos-methyl would affect the survival and the predatory abilities of B. tarsalis. First, we conducted survival bioassays to estimate the median survival time (LT₅₀) of B. tarsalis when exposed to Bt_i-based insecticide (at 0.25 and 25?mg a.i./L) and pirimiphos-methyl (at 1, 10 and 1000?mg a.i./L). The highest concentrations of the insecticides were equivalent to the label-recommended field rates. Second, the predatory abilities of B. tarsalis exposed to insecticides were evaluated at three prey densities (3, 6 and 9 mosquito larvae/100?mL water) just after insecticide exposure or after a 24?h recovery time. While the survival of B. tarsalis was significantly reduced with pirimiphos-methyl concentrations ≥10?mg a.i./L, the Bt_i-exposed predators exhibited similar survival as unexposed predators. Interestingly, after a recovery time of 24?h, B. tarsalis sublethally exposed to pirimiphos-methyl or Bt_i-based insecticide consistently killed more A. aegypti larvae (at the intermediate density) than unexposed predators. However, for the without-recovery bioassays, the pirimiphos-methyl-exposed predators exhibited reduced predatory abilities at the lowest prey density. Because they do not reduce the survival or the predatory abilities of B. tarsalis, Bt_i-based insecticides can be considered a safe insecticide to use in the presence of backswimmers.     

Sensitivity of <Emphasis Type="Italic">Scenedesmus obliquus</Emphasis> and <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> to atrazine: effects of acclimation and mixed cultures,and their removal ability

Atrazine is an herbicide frequently detected in watercourses that can affect the phytoplankton community, thus impacting the whole food chain. This study aims, firstly, to measure the sensitivity of monocultures of the green alga Scenedemus obliquus and toxic and non-toxic strains of the cyanobacteria Microcystis aeruginosa before, during and after a 30-day acclimation period to 0.1?µM of atrazine. Secondly, the sensitivity of S. obliquus and M. aeruginosa to atrazine in mixed cultures was evaluated. Finally, the ability of these strains to remove atrazine from the media was measured. We demonstrated that both strains of M. aeruginosa had higher growth rate-based EC₅₀ values than S. obliquus when exposed to atrazine, even though their photosynthesis-based EC₅₀ values were lower. After being exposed to 0.1?µM of atrazine for 1?month, only the photosynthesis-based EC₅₀ of S. obliquus increased significantly. In mixed cultures, the growth rate of the non-toxic strain of M. aeruginosa was higher than S. obliquus at high concentrations of atrazine, resulting in a ratio of M. aeruginosa to total cell count of 0.6. This lower sensitivity might be related to the higher growth rate of cyanobacteria at low light intensity. Finally, a negligible fraction of atrazine was removed from the culture media by S. obliquus or M. aeruginosa over 6?days. These results bring new insights on the acclimation of some phytoplankton species to atrazine and its effect on the competition between S. obliquus and M. aeruginosa in mixed cultures.     

Exposure of the freshwater bivalve <Emphasis Type="Italic">Hyridella australis</Emphasis> to metal contaminated sediments in the field and laboratory microcosms: metal uptake and effects

Metal uptake and induced toxic effects on Hyridella australis were investigated by establishing 28 day exposure–dose–response relationships (EDR) of transplanted H. australis at four sites along a sediment metal contamination gradient in the mine affected Molonglo River, NSW. Laboratory exposure of this organism to the same sediments, collected from in situ sites, was run concurrently. Metal concentrations in whole organisms, individual tissues and sub-cellular tissue fractions were measured as organism metal dose. Total antioxidant capacity (TAOC), lipid peroxidation (MDA) and lysosomal membrane destabilisation (LMS) were measured as biological responses. H. australis accumulated significantly higher tissue zinc concentrations compared to the other metals. In situ organisms at the mine affected sites accumulated more metals than organisms in laboratory microcosms. Accumulated zinc, cadmium and the total metal concentrations in whole organism tissues reflected exposure–dose relationships. Sub-cellular analysis showed that most of the accumulated metals, both in the field and laboratory exposed organisms, were detoxified over 28 days exposure. Clear exposure and dose dependent responses of decreased TAOC and measurable increases in MDA and LMS with increased metal exposure and dose were evident in H. australis caged in the river. In contrast, a dose–response relationship was only evident for cadmium in laboratory exposed organisms. Organisms caged at mine affected sites showed stronger EDR relationships than those exposed in laboratory microcosms as they were exposed to additional sources of dissolved zinc and cadmium. Exposure in laboratory microcosms underestimated metal uptake and effects, thus assessment of metal contaminated sediments should be undertaken “in situ”.     

Effect of Cd<Superscript>+2</Superscript> on phosphate solubilizing abilities and hydrogen peroxide production of soil-borne micromycetes isolated from <Emphasis Type="Italic">Phragmites australis</Emphasis>-rhizosphere

The aims of this work were to evaluate the phosphate-solubilization and hydrogen peroxide (H₂O₂) production by the soil-borne micromycetes, Aspergillus japonicus, Penicillium italicum and Penicillium dipodomyicola, isolated from Phragmites australis rhizosphere and to study the effect of several concentrations of Cadmium (Cd²⁺) on both variables. Our results showed that P. italicum achieved a higher P-solubilization and H₂O₂ production than A. japonicus and P. dipodomyicola, as only P. italicum showed a positive correlation (R² = 0.71) between P-solubilization and H₂O₂ production. In dose–response assays, P. italicum was also more tolerant to Cd²⁺ (0.31 mM) in comparison to A. japonicus (0.26 mM). Analysis of the 2⁴ factorial experimental design showed that P-solubilization by P. italicum was negatively affected by increases in Cd²⁺ (p = 0.04) and yeast extract (p = 0.02) in the culture medium. The production of H₂O₂ was positively affected only by glucose (p = 0.002). Fungal biomass production was reduced significantly (p = 0.0009) by Cd²⁺ and increased (p = 0.0003) by high glucose concentration in the culture medium. The tolerance and correlation between P-solubilization and H₂O₂ production in the presence of Cd²⁺ was strain and species dependent. The effects of Cd²⁺, glucose, ammonium sulfate and yeast extract on those variables were evaluated through a two-level factorial design. P. italicum is promising for P-solubilization in soils contaminated with Cd²⁺ and may be an alternative for manufacture of biofertilizers to replace chemical fertilizers.     

Synthesis and biological evaluation of some functionalized 1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazole tethered pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridin-6(7<Emphasis Type="Italic">H</Emphasis>)-ones as antimicrobial and apoptosis inducing agents

A series of novel molecular hybrids containing pyrazole, pyridinone and 1,2,3-triazoles have been synthesized by one-pot four-component reaction of Meldrum’s acid, substituted aryl azides, 4-(prop-2-yn-1-yloxy)aryl aldehyde and 3-methyl-1-phenyl-1H-pyrazol-5-amine using L-proline as a basic organocatalyst besides CuSO₄.5H₂O and sodium ascorbate as catalysts for click chemistry in PEG-400 as a highly efficient and green media. Apoptosis studies have been carried out on ovarian follicles of goat (Capra hircus) and in vitro antibacterial activity has been done against six strains namely Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa and antifungal activity against two yeast strains namely, Candida albicans and Saccharomyces cerevisiae.     

Detection of insecticide resistance in <Emphasis Type="Italic">Bradysia odoriphaga</Emphasis> Yang <Emphasis Type="Italic">et</Emphasis> Zhang (Diptera: Sciaridae) in China

Bradysia odoriphaga Yang et Zhang is a destructive insect pest of Chinese chives. To understand the current status of insecticide resistance of B. odoriphaga in China, the sensitivity variation of eight field populations to six commonly used insecticides, including chlorpyrifos, phoxim, imidacloprid, thiamethoxam, clothianidin and beta-cypermethrin were evaluated. The results showed that almost all the tested B. odoriphaga populations had developed moderate to high resistance to chlorpyrifos and phoxim. There were different resistance levels found in the eight field populations among the three neonicotinoids, imidacloprid, thiamethoxam and clothianidin. Imidacloprid was very effective against B. odoriphaga in most tested populations except those from Yangzhou (10.35-fold) and Tangshan (14.56-fold). While four populations kept susceptible to thiamethoxam, the other four populations showed decreased susceptibility or low resistance. To clothianidin, five populations displayed moderate resistance, two populations displayed low resistance, and one population exhibited susceptibility, respectively. All the tested populations were resistance to beta-cypermethrin, the highest resistance was found in the Tangshan population with a resistance ratio of 172.56-fold. The results of this study provided valuable information for choosing insecticides for control and integrated resistance management of B. odoriphaga.     

Limitations in dose–response and surrogate species methodologies for risk assessment of Cry toxins on arthropod natural enemies

Dose–response assays and surrogate species are standard methods for risk analysis for environmental chemicals. These assume that individuals within a species have unimodal responses and that a surrogate species can predict responses of other related taxa. We exposed immature individuals of closely related aphidophagous coccinellid predators, Cycloneda sanguinea and Harmonia axyridis, to Cry1Ac and Cry1F toxins through uniform and constant artificial tritrophic exposure through Myzus persicae aphids. Both toxins were detected in coccinellid pupae, with individual and interspecific variation. Uptake was significantly higher in H. axyridis than in C. sanguinea, both in the proportion of individuals and the concentrations per individual. We also observed bimodal uptake of the Cry toxins by H. axyridis, which indicated that some individuals had low bioaccumulation and some had high bioaccumulation. This suggests that standard dose–response assays need to be interpreted with caution and future assays should examine the modality of the responses. In addition, the similarity in the biological effects of the Cry toxins in the two predators was due to different biological exposure mechanisms. The majority of H. axyridis were exposed both internally and in the gut, while C. sanguinea was exposed primarily in the gut. Thus, despite their close phylogenetic relatedness, these species would not be good surrogates for each other and the surrogate species methodology should be tested more rigorously.     

Effects of <Emphasis Type="Italic">Bacillus thuringiensis var. israelensis</Emphasis> on nonstandard microcrustacean species isolated from field zooplankton communities

The toxicity of Bacillus thuringiensis var. israelensis on zooplanktonic microcrustaceans was evaluated using individuals collected in coastal wetlands where this larvicide has been used for mosquito control over the last decades. We tested five zooplankton species that coexist with mosquito larvae: two copepods (both nauplii and adults of Tropocyclops prasinus and Acantocyclops americanus), and three cladocerans (Ceriodaphnia reticulata, Chydorus sphaericus, and Daphnia cf. pulex). Our experiments included seven replicates of six concentrations (Bti Vectobac12AS 1200 Bti ITU/mg): 0, 5, 25, 50, 250, and 500?mg L^?1. We analyzed acute and sub-chronic effects after a single inoculation. Despite the high variability of responses among our tested organisms, we found a general pattern of increasing mortality with concentration and time. We conclude that negative effects at the community level are not unlikely as some species were affected at doses close to those used in field applications.     

Identification of <Emphasis Type="Italic">N</Emphasis>-arylsulfonylpyrimidones as anticancer agents

For confirming the role of five membered ring of imidazolidinone moiety of N-arylsulfonylimidazolidinones (7) previously reported with highly potent anticancer agent, a series of N-arylsulfonylpyrimidones (10a–g) and N-arylsulfonyltetrahydropyrimidones (11a–e) were prepared and their anti-proliferating activity was measured against human cancer cell lines (renal ACHN, colon HCT-15, breast MDA-MB-231, lung NCI-H23, stomach NUGC-3, and prostate PC-3) using XTT assay. Among them, 1-(1-acetylindolin-5-ylsulfonyl)-4-phenyltetrahydropyrimidin-2(1H)-one (11d, mean GI₅₀ = 3.50 µM) and ethyl 5-(2-oxo-4-phenyltetrahydropyrimidin-1(2H)-ylsulfonyl)-indoline-1-carboxylate (11e, mean GI₅₀ = 0.26 µM) showed best growth inhibitory activity against human cancer cell lines. Considering the activity results, N-arylsulfonyltetrahydropyrimidones (11) exhibited more potent activity compared to N-arylsulfonylpyrimidones (10) and comparable activity to N-arylsulfonylimidazolidinones (7). Especially, tetrahydropyrimidin-2(1H)-one analogs containing acylindolin-5-ylsulfonyl moiety at position 1 demonstrated their strong growth inhibitory activity against human cancer cell lines.