The striped lynx spider,Oxyopes salticus [Araneae: Oxyopidae], in agroecosystems

The striped lynx spider,Oxyopes salticus Hentz, is among the numerically dominant predators in row crops in the United States and is described as a major predator of economically important pests. Because of its potential as a biocontrol agent of numerous pests, a review of the literature was undertaken. Eighty-eight publications are referenced, presenting the available data onO. salticus up to 1984.

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Résumé L'araignée lynx rayée,Oxyopes salticus figure parmi les prédateurs numériquement dominants dans les cultures en lignes des Etats-Unis d'Amérique. C'est un prédateur majeur des ravageurs économiques importants. A cause de son potentiel en tant qu'agent biologique de lutte de nombreux ravageurs, une revue bibliographique a été entreprise: 88 publications qui présentent les données disponibles jusqu'en 1984, sont mentionnées.

     

Sublethal pesticide exposure disrupts courtship in the striped lynx spider,Oxyopes salticus (Araneae: Oxyopidae)

The striped lynx spider, Oxyopes salticus, is a dominant predator of pests in agricultural crops where pesticides are readily applied. While past research shows pesticides directly affect the mortality of agricultural pest predators, recent research has found that pesticide exposure may cause sublethal effects in these organisms. This study examined how residues of three common pesticides (active ingredients: bifenthrin, carbaryl, malathion) impact courtship behaviour of O. salticus. Males provided with cues left by females readily performed courting behaviours. However, when females left cues on a substrate containing bifenthrin and carbaryl, males were less likely to perform courtship behaviours and did so for less time. While males on the malathion treatment showed a trend for reduced courting, this was not significantly different from the treatment without pesticides. The cue produced by females is unknown in this species. However, our study found males reduced their courting over time, suggesting that the cue is ephemeral and not long lived. This study adds important insight into the growing evidence that pesticides greatly impact the ecology of agricultural pest predators and other non‐target organisms by altering their behaviour.     

Food imprinting and subsequent prey preference in the lynx spider,Oxyopes salticus (Araneae: Oxyopidae)

This object of this study was to determine if early feeding experience can affect subsequent prey choice in lynx spiderlings (Oxyopes salticus), and if so, is it evidence for food/olfactory imprinting. After emergence from the egg sac, three groups of 10 spiderlings were each fed exclusively for a 1-week period on one of three naturally-occurring prey species (crickets): group 1 fed on nymphs of Gryllotalpa hexadactyla; group 2 (Dialeurodes citrifoli); group 3 (Microcentrum rhombifolium). Following this, they were tested for subsequent prey preference in choice tests conducted in a plastic arena. Each spiderling was presented simultaneously with one individual of each prey species in a randomized design. Spiderlings exhibited a significant first preference for the original diet. Thus, experience with certain foods encountered by newly hatched spiderlings can affect subsequent prey preference in this species. Given the primacy of the early experience, the results are best interpreted in terms of imprinting and represent the first demonstration of olfactory imprinting in a spider.     

Lethal and sublethal effects of Embelia ribes and two commercial pesticides on a generalist predator

Even as new substances show promise as biopesticides for controlling pests due to their natural properties and high effectiveness in inhibiting pests, their side effects on non‐target organisms must nevertheless be evaluated before they can be included into integrated pest management systems. In this study, a crude extract from dried leaves of Embelia ribes was evaluated together with two commercial pesticides: azadirachtin (a natural product) and amitraz (a synthetic acaricide). We examined both lethal and sublethal effects on the predatory potential of the lynx spider Oxyopes lineatipes, which is among the most dominant predator in tropical agricultural agroecosystems. We found that the spider's mortality increased with rising concentration of both commercial products, azadirachtin and amitraz, but not with rising concentration of the extracts from E. ribes. The greatest mortality occurred when amitraz was used. That material caused almost 100% spider mortality in the doses recommended for field spraying. Azadirachtin significantly reduced the rate at which O. lineatipes captured prey, while there was no significant difference in capture rates among spiders exposed to a control treatment and the E. ribes treatment. Considering its absence of unfavourable impacts on O. lineatipes in terms of mortality and predatory activity, the plant extract from E. ribes shows promise as a new biopesticide material. In contrast, azadirachtin, which has been considered as safe for non‐target organisms, exhibited slight lethal effect only in higher concentrations and strong sublethal effect by reducing spiders’ predation rate.     

Residual effects of four pesticides on the predatory bug,Orius albidipennis Reut. (Hem.: Anthocoridae)

Residual effects of abamectin (0.02%), propargite (0.1%), dichlorvos (DDVP) (0.15%) and pymetrozine (0.15%) were determined on Orius albidipennis at laboratory conditions. Planted cucumbers were sprayed with the highest recommended concentrations of all insecticides and experimental treatments were monitored during 20 days based on the period of pesticides residues. On the first day after spraying, the greatest of mortality belonged to dichlorvos and pymetrozine (97 ± 1.22, 57 ± 3.1, respectively, p < 0.01), while abamectin and propargite had the highest mortality after four (44 ± 1.87 and 24 ± 2.91, respectively, p < 0.01) and eight (51 ± 2.91 and 17 ± 2.23, respectively, p < 0.01) days after spraying. At day 16th, post treatment, abamectin had the highest residual mortalities on O. albidipennis (15 ± 1.58, p < 0.01) and finally mortality results at the 20th day showed there is no significant difference between insecticides (p < 0.01).     

Transovarial toxicity matters: lethal and sublethal effects of hexythiazox on the two-spotted spider mite (Acari: Tetranychidae)

The effects of hexythiazox on life-history traits and demographic parameters of Tetranychus urticae Koch (Acari: Tetranychidae) were evaluated using the age-stage two-sex life table (in fecundity-based and fertility-based variants), with emphasis on its transovarial toxicity. Hexythiazox was applied when T. urticae females were either in the preovipositional period or in the first day of oviposition. In the F₀ generation bioassay, treatments with concentrations of 50, 12.5 and 3.125 mg/l significantly reduced the longevity of females and their fecundity. These effects were mostly the result of mortality of treated females (18–23%) over the 24-h exposure period. Even though the net reproductive rate (R₀) decreased significantly, the intrinsic rate of increase (r), finite rate of increase (λ) and doubling time (D) were not significantly different from the control. The strongest transovarial toxic effect occurred within the first 4 days following treatment, when 52–89% of the eggs laid by treated females (96% in control) hatched. Fertility was significantly reduced by concentrations of 50, 12.5, 3.125, 0.781 and 0.195 mg/l. These concentrations caused significant reductions in R₀ (34–54%), r (12–24%) and λ (3–5%), whereas D was extended for 0.4–0.7 days. In the F₁ generation bioassay, 50, 12.5, 3.125, 0.781, 0.049 and 0.012 mg/l caused significant reductions in R₀ (34–92%), r (10–68%) and λ (3–17%), whereas extending D for 0.3–5.6 days. These effects were mostly the consequence of transovarial toxicity. Application of the fecundity-based life table underestimated population-level effects of hexythiazox on T. urticae.

     

Uniformity of petroleum‐derived spray oils: lethal and sublethal effects on a herbivore pest and its parasitoid

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The impact of aphicide drenches on Micromus tasmaniae (Walker) (Neuroptera: Hemerobiidae) and the implications for pest control in lettuce crops

Abstract  The recent arrival of lettuce aphid ( Nasonovia ribis-nigri (Mosley) ) in Australia has resulted in a pesticide-based protection program based upon seedling drenches of imidacloprid being promoted by many advisory agencies and accepted by growers as the only option available. This has caused concern about potential for incompatibility with existing integrated pest management programs for other pests in lettuce. Two neonicotinoid insecticides, imidacloprid (Confidor 200SC) and thiamethoxam (Actara), were applied to lettuce seedlings by drenching. A model aphid ( Macrosiphum euphorbiae (Thomas) ), used because N. ribis-nigri was not present in mainland Australia at that time, was periodically released onto the seedlings over 10 weeks. The effects of imidacloprid and thiamethoxam on larvae of predatory brown lacewings ( Micromus tasmaniae (Walker) ) which fed on the aphids were measured over 10 weeks by bioassay. Imidacloprid applied at a rate of 11 mL active ingredient (ai) per 1000 seedlings and thiamethoxam applied at 0.5 g ai per 1000 seedlings were highly toxic to M. tasmaniae that consumed aphids from the seedlings for up to 4 weeks after application. A 1/10 rate of imidacloprid (1.1 mL ai per 1000 seedlings) caused moderate toxicity for 3 weeks, and was then harmless to M. tasmaniae . Thiamethoxam and the high rate of imidacloprid caused almost complete mortality of aphids for about 6 weeks after application, and the low rate of imidacloprid displayed similarly high activity for about 3 weeks.     

一种新杀虫剂对储粮害虫和作物害虫的杀虫效果

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Lethal and sublethal effects of cypermethrin and methoxyfenozide on the larvae of Rachiplusia nu (Guenee) (Lepidoptera: Noctuidae)

Rachiplusia nu is a defoliator lepidopteran species considered a potential pest in soybean and other crops. Cypermethrin is the main insecticide used in Argentina. Worldwide trends in pest control promote the use of insecticides with high specificity like methoxyfenozide; however, their usage in South America is still incipient. The effectiveness of cypermethrin and methoxyfenozide was studied on fifth larval instar of R. nu under chronic exposure in laboratory conditions. Four dilutions (between 10% and 80%) of the maximum field recommended concentration for each insecticide were assessed. Methoxyfenozide caused 100% larval mortality in all tested concentrations, while at tested cypermethrin concentrations, larval mortalities were between 75% and 98%. Cypermethrin treatments showed higher mean survival time values than methoxyfenozide. Both insecticides inhibited larval growth according to weight loss assessment. Cypermethrin also inhibited diet consumption during the first 24-h exposure.     

Modular toxin from the lynx spider Oxyopes takobius: Structure of spiderine domains in solution and membrane‐mimicking environment

We have recently demonstrated that a common phenomenon in evolution of spider venom composition is the emergence of so‐called modular toxins consisting of two domains, each corresponding to a “usual” single‐domain toxin. In this article, we describe the structure of two domains that build up a modular toxin named spiderine or OtTx1a from the venom of Oxyopes takobius. Both domains were investigated by solution NMR in water and detergent micelles used to mimic membrane environment. The N‐terminal spiderine domain OtTx1a‐AMP (41 amino acid residues) contains no cysteines. It is disordered in aqueous solution but in micelles, it assumes a stable amphiphilic structure consisting of two α‐helices separated by a flexible linker. On the contrary, the C‐terminal domain OtTx1a‐ICK (59 residues) is a disulfide‐rich polypeptide reticulated by five S–S bridges. It presents a stable structure in water and its core is the inhibitor cystine knot (ICK) or knottin motif that is common among single‐domain neurotoxins. OtTx1a‐ICK structure is the first knottin with five disulfide bridges and it represents a good reference for the whole oxytoxin family. The affinity of both domains to membranes was measured with NMR using titration by liposome suspensions. In agreement with biological tests, OtTx1a‐AMP was found to show high membrane affinity explaining its potent antimicrobial properties.     

Control effects and sublethal effects of four pesticides on Atheloca bondari (Lepidoptera: Pyralidae) caterpillars

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Comparative toxic and sublethal effects of fluvalinate on two-spotted spider mite and European red mite

Four fluvalinate formulations differed in their residual toxicity to female two-spotted spider mite (TSM), Tetranychus urticae adults; the emulsifiable concentrate (EC) was the most toxic. In contrast, there was little difference in toxicity between the formulations with the European red mite (ERM) Panonychus ulmi with the exception of the EC formulation which was the least toxic. Fluvalinate 2F caused minimal (<10%) TSM and ERM egg mortality. Fluvalinate 2F was more toxic and caused greater larval dispersal for the TSM compared to the ERM at the field concentration and below. The toxicity of fluvalinate 2F to TSM and ERM protonymphs, deutonymphs and adults was low, approximately <20% at field concentration. Dispersal was the main response to fluvalinate and this was positively correlated with increasing concentration. The combined mortality and dispersal LC₅₀ was five times lower for ERM protonymphs and adults, but 11 times higher for ERM deutonymphs compared to equivalent TSM life stages. Fluvalinate 2F reduced TSM development from the protonymph and deutonymph stages to a greater extent compared to the ERM. The mortality response to fluvalinate 2F was unaffected by host type (peach or apple) for the TSM whereas ERM mortality was higher on apple compared to peach. TSM dispersal was higher from apple compared to peach whereas ERM dispersal was similar on both host types. Oviposition by both mite species was lower on apple than peach leaves. A 1 h exposure to fluvalinate 2F reduced ERM oviposition for 12 days.     

Synergistic effects of heat and diatomaceous earth treatment for the control of Plodia interpunctella (Lepidoptera: Pyralidae)

Plodia interpunctella is a major economic pest that commonly infests most stored and processed agricultural products. Currently, heating at 50–60°C for at least 48 h is applied in facilities for disinfestation. However, this condition requires a great deal of time and expense. To improve the control efficiency of this system, we conducted combined treatments with heating and diatomaceous earth (DE), which is known to be toxic to pest insects. The DE effect was compared to heating at 25°C or 40°C to wandering fifth instar larvae, which is the stage most tolerant to heat. When larvae were brushed with DE powder, mortality was only 15.0–18.3% at 25°C for 10 days, but rapidly increased to 100% at 40°C within 4 h post‐treatment. In addition, when larvae were kept in a plastic cage with DE [4 mg/L (w/v)], their mortality was 100% in 24 h at 40°C post‐treatment; otherwise mortality was only 8.8% without DE. Thus, the control efficiency of heating significantly improved with the combination of DE. These effects increased further at higher temperatures and with longer exposure. Our results clearly showed that DE treatment showed synergistic effects with heating systems for the control of P. interpunctella.     

Comparative residual toxicities of pesticides to the predator Agistemus industani (Acari: Stigmaeidae) on citrus in Florida

Residual toxicities of registered and selected experimental pesticides used on citrus against Agistemus industani Gonzalez (Acari: Stigmaeidae) were compared. Pesticides considered highly toxic to A. industani were: abamectin 0.15 EC at 731ml/ha+FC 435-66 petroleum oil at 46.8l/ha, pyridaben 75WP at 469g/ha, ethion 4EC at 7.01l/ha+FC 435-66 petroleum oil at 46.8l/ha, propargite 6.55 EC at 3.51l/ha, chlorfenapyr 2SC at 1.46l/ha applied alone or in combination with FC 435-66 petroleum oil at 46.8l/ha, sulphur 80DF at 16.81kg/ha, dicofol 4EC at 7.01l/ha, fenbutatin oxide 50WP at 2.24kg/ha, benomyl 50WP at 2.24kg/ha, benomyl 50WP at 1.68kg/ha+ferbam 76 GF at 5.60kg/ha, ferbam 76GF at 11.21kg/ha, neem oil 90EC at 46.8l/ha, and copper hydroxide DF (40% metallic copper) at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha. Pesticides that were moderately to slightly toxic included: copper sulphate 98% at 4.48kg metallic copper/ha+FC 435-66 petroleum oil at 46.8l/ha, fenbuconazole 2F at 280ml/ha+FC 435-66 petroleum oil at 46.8l/ha, FC 435-66 petroleum oil applied alone at 46.8l/ha or 23.4l/ha, and diflubenzuron 25WP at 1.40kg/ha. Pesticides that were non-toxic included: fenbuconazole 2F at 585ml/ha, malathion 57EC at 5.85l/ha, FC 435-66 petroleum oil at 46.8l/ha, carbaryl 80S at 3.36kg/ha, chlorpyrifos 4EC at 4.68l/ha, and formetanate 92SP at 1.12kg/ha. Understanding the toxic effects of field weathered pesticides against key predacious mite species is important for effective IPM. The results of this study provide a comparison of direct and indirect toxic effects of various pesticides to A. industani under field conditions.     

Acaricidal activity and sublethal effects of an oxymatrine-based biopesticide on two-spotted spider mite (Acari: Tetranychidae)

Lethal and sublethal effects of the biopesticide Kingbo (oxymatrine 0.2 % + psoralen 0.4 %) on the two-spotted spider mite (Tetranychus urticae Koch) were investigated in laboratory bioassays. The biopesticide was applied to bean leaf discs or primary leaves by using a Potter spray tower. Acute toxicity tests showed no significant ovicidal action: toxic effect (LC₅₀ = 55.49 μl/l) was the result of a residual activity against larvae that hatched from the treated eggs. Preovipositional females and female teleiochrysales showed similar susceptibility (LC₅₀ = 52.68 and 59.03 μl/l, respectively), whereas larvae, protonymphs and female deutonymphs were the most susceptible stages (LC₅₀ = 6.88, 13.03, and 8.80 μl/l, respectively). In a choice test, females preferred the untreated halves of leaves over the halves treated with 2,000, 1,000, and 500 μl/l in the first 24 h, and their oviposition in those treatments was significantly greater on the untreated halves after 24 and 48 h, as well as the summed oviposition over 72 h. Viability and reproduction of survivors, as well as population growth, were strongly affected after the treatments of preovipositional females and female teleiochrysales with 100, 50 and 25 μl/l. On the other hand, sublethal effects on the females that survived treatment at the egg stage or reached adulthood from the eggs laid on the treated surface (treatments with 50 and 25 μl/l) were significantly weaker. Acaricidal and sublethal effects of the biopesticide Kingbo were discussed as a starting point for further research aimed to improve management of T. urticae populations. Regulatory issues and safety concerns regarding further commercialization of this biopesticide are addressed as well.     

Influence of habitat and microhabitat on epigeal spider (Araneae) assemblages in four stand types

Studies based on presence/absence of a species may provide insight into habitat associations, allowing the distribution of species to be predicted across the landscape. Our objective was to characterise the epigeal spider fauna in three mature boreal forest types (conifer, mixedwood and deciduous) and a disturbed habitat (clearcut) to provide baseline data on the spider species inhabiting major forest types of boreal northwestern Ontario, Canada. Only spring-active epigeal spiders were considered for logistical reasons. We further identified the coarse woody debris structure and microhabitat characteristics within these stand types to try to refine our ability to predict the within-stand occurrence of spiders. We found the clearcut habitat strongly dominated by the Lycosidae with 55% of spiders represented by a single species, Pardosa moesta Banks. The forested habitats were more diverse, with web-building families forming a large component of the fauna and many species represented by only a few individuals. The spider composition of the deciduous stands (aspen and mixedwood) was very similar, and distinct from that of spruce stands. Species such as Agroeca ornata (Emerton) (Liocranidae) and Pirata montanus Emerton (Lycosidae) were strongly associated with deciduous leaf litter. Within the spruce stands, Agyneta olivacea (Emerton) (Linyphiidae) and Pardosa uintana Gertsch (Lycosidae) were associated with feathermoss rather than Sphagnum microhabitats. Many of the habitat associations observed at Rinker Lake do not conform well to those described in the taxonomic literature as typical for the species. Few associations with coarse woody debris or microhabitat attributes (other than ground cover type) were found.     

三种农药对红裸须摇蚊毒力和羧酸酯酶活性的影响

摇蚊是一种世界性分布的水生昆虫,常作为监测水环境污染指示生物。以红裸须摇蚊为对象,测定了氧化乐果、毒死蜱和三氟氯氰菊酯对红裸须摇蚊4龄幼虫毒力和体内羧酸酯酶活性的影响。结果表明,氧化乐果、毒死蜱和三氟氯氰菊酯12 h 致死中浓度LC₅₀分别为12.508、2.478和0.046 μg/L。低浓度(0.05 μg/L)氧化乐果处理3 h和12 h以及各浓度(除8 μg/L)氧化乐果处理48 h,摇蚊体内羧酸酯酶活性均高于对照,表现为诱导作用,其余各浓度各处理时间均表现为抑制减少。除0.125 μg/L和0.25 μg/L毒死蜱处理12 h对羧酸酯酶有诱导作用外,毒死蜱均抑制羧酸酯酶活性;而三氟氯氰菊酯也均抑制羧酸酯酶活性。因此,摇蚊羧酸酯酶可作为一种监测农药污染的生物化学标志物加以利用。