Predatory Spiders Research Articles

Effect of some Insecticides on Pink Bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), Associated Predators in Cotton Field and some of their Biochemical Effects

Efficiency of profenofos, chlorpyrifos and alpha-cypermethrin against Pectinophora gossypiella and their associated predators in cotton field at Zagazig, Sharkia Governorate. Alpha-cypermethrin increased mean seasonal reduction percentages (92.92%), while, profenofos decrease it (78.38%). Alpha-cypermethrin caused the highest mean seasonal reduction percentages in the Coccineledae, Chrysoperla carnea and True spider predators (88.26, 73.67 and 85.70%, respectively). The pupal mortality percentage increased while, pupal duration, adult emergency percentage, pupal weight, pupation percentage, deposited eggs and hatchability percentage decreased. The activity of trehalase, invertase and acetylcholine esterase enzymes decreased but of amylase and AST (Aspartate aminotransferase) increased. Disturbance recorded in ALT (Alanine aminotransferase) enzyme, total lipid and total soluble protein content relative to control.

Starvation Time and Predatory Efficiency of Spider Species on Bemisia tabaci (Homoptera: Aleyrodidae)

Four predatory spider species, Leucauge venusta (Orchard) (Araneae: Tetragnathidae), Lycosa pseudoannulata (Boeset) (Araneae: Lycosidae), Larinioides cornutus (Clerck) (Araneae: Araneidae), and Tetragnatha shikokiana (Yaginuma) (Araneae: Tetragnathidae), were used to control Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in the laboratory and greenhouse, and their longevity without food was observed. For the laboratory experiment, the spiders' feeding capabilities were checked at 1, 4, 8, and 16 h of exposure in a 10 mL vial containing 50 five-d-old whiteflies. For the greenhouse experiment, the preys' feeding ability was recorded at 24 and 48 h, with 100 five-d-old adult whiteflies in a screened cage. Individual spiders were kept in the lab in 10 mL vials, and their survival time was recorded every 5 h. Of the 4 spider species, L. pseudoannulata was the most active in the lab and consumed an average of 3.00 ± 0.22, 6.17 ± 0.27, 9.67 ± 0.43, and 13.50 ± 0.49 at 1, 4, 8, and 16 h of the bioassay, followed by L. venusta, L. cornutus, and T. shikokiana. However, in the greenhouse experiment, L. venusta consumed the greatest number of whiteflies, with an average of 24.66 and 51.33 (out of 100) at 24 and 48 h, respectively, followed by L. pseudoannulata, L. cornutus, and T. shikokiana. The maximum longevity was recorded for L. venusta with 26.67 h, followed by T. shikokiana, L. pseudoannulata, and L. cornutus without prey. All spider species killed and consumed adult whiteflies in both experiments, which suggests that they are a controlling tool in the natural ecosystem. The results from our experiment will contribute to the biological control of whitefly.

Consuming alternative prey does not influence the DNA detectability half-life of pest prey in spider gut contents.

BackgroundKey natural enemy-pest interactions can be mapped in agricultural food webs by analysing predator gut content for the presence of a focal pest species. For this, PCR-based approaches are the most widely used methods providing the incidence of consumption of a focal pest in field sampled predators. To interpret such data the rate of prey DNA decay in the predators’ gut, described by DNA detectability half-life (t1/2), is needed. DNA decay may depend on the presence of alternative prey in the gut of generalist predators, but this effect has not been investigated in one of the major predatory arthropod groups, spiders.MethodsIn a laboratory feeding experiment, we determined t1/2 of the key cereal pest virus vector leafhopper Psammotettix alienus in the digestive tracts of its natural enemy, the spider Tibellus oblongus. We followed the fate of prey DNA in spiders which received only the focal prey as food, or as an alternative prey treatment they also received a meal of fruit flies after leafhopper consumption. After these feeding treatments, spiders were starved for variable time intervals prior to testing for leafhopper DNA in order to establish t1/2.ResultsWe created a PCR protocol that detects P. alienus DNA in its spider predator. The protocol was further calibrated to the digestion speed of the spider by establishing DNA decay rate. Detectability limit was reached at 14 days, where c. 10% of the animals tested positive. The calculated t1/2 = 5 days value of P. alienus DNA did not differ statistically between the treatment groups which received only the leafhopper prey or which also received fruit fly. The PCR protocol was validated in a field with known P. alienus infestation. In this applicability trial, we showed that 12.5% of field collected spiders were positive for the leafhopper DNA. We conclude that in our model system the presence of alternative prey did not influence the t1/2 estimate of a pest species, which makes laboratory protocols more straightforward for the calibration of future field data.

Plants trap pollen to feed predatory arthropods as an indirect resistance against herbivory

Plants commonly employ indirect resistance to reduce herbivory by provisioning predatory arthropod populations with additional resources. Numerous predatory arthropods consume pollen that is entrapped on dense, wooly trichomes of plants. Over two seasons, we supplemented pollen on the wooly leaves of turkey mullein, Croton setiger, in natural populations to determine if pollen entrapped on leaves supplements predatory arthropods and reduces herbivore populations and damage to the plant. Pollen supplementation increased the abundance of predatory spiders in both years and omnivorous Orius bugs in 1yr but had no effect on predatory hemipterans. Pollen supplementation reduced the abundance of herbivorous fleahoppers. Pollen supplementation decreased the amount of leaf damage experienced by plants over the season, suggesting that pollen entrapment may act as an indirect resistance. While C. setiger plants have little control over the amount of pollen on their surfaces, pollen adds to the diet of predatory arthropods that reduce herbivory, thus attraction of predators may be an adaptive benefit of leaf structures such as wooly trichomes that entrap pollen.

Effect of some plant essential oils on the orientation and predation capacity of the predatory spider Pardosa pesudoannulata

Abstract Investigating the potential side-effects of plant essential oils to natural enemies is necessary before applying them in the field to control insect pests. In the present laboratory study, the attractancy/repellency of two plant oils to the spider Pardosa pseudoannulata was evaluated using a paired choice method. An individual spider was allowed to choose between the odors of essential oils extracted from Piper nigrum, Litsea cubeba, or their mixture and the control within 10 min. The predation deterrent was evaluated by observing the predation of caged spiders supplied with 20 nymphs or adults of Nephotettix cincticeps pre-treated with essential oils in 24 h. Results revealed that P. nigrum and L. cubeba oil had no significant influence on the orientation of the predator in all tested concentrations. However, the mixture of P. nigrum and L. cubeba triggered significant attraction to P. pseudoannulata at 100 and 1000 ppm. Significant reduction of predation was observed with increasing concentration of the mixture and P. nigrum alone. The predation rate in the L. cubeba assay was not significantly different among the tested concentrations. In all cases, predation was higher on nymphs than on adult stages. We did not observe any interaction effect between the life stages and concentrations. To our knowledge, this is the first study discussing the potential influence of plant essential oils on orientation and predation of P. pseudoannulata. Based on these results, some essential oils and their combinations may influence the orientation of P. pseudoannulata and might affect its predation capacity. Further field studies are needed, but these findings suggest caution regarding the selection and application of plant extracts used for biological control in rice fields.

Tritrophism in mellitophylic Cleome viscosa L.

Cleome viscosa L. is an annual summer blooming herb. A generalized group of pollinators like Apis dorsata, A. cerana, Halictus albescens, Ceratina heiroglyphica, Nomia elliotii, N. curvipes and Eurema hecabae mediate within and between plant, pollen flow thereby contributing to geitonogamy and xenogamy respectively. Relationship of mutualism thereby exists in which pollinators are offered nutrient rich pollen and nectar for favour of transferring male units (pollen) between flowers. Interestingly, the plants were also observed to be associated with certain spiders of order Arachnidales (Thomisus, Neoscona and Peucetia). All these spiders via behavioural mimicry parasitize bees which actually are the efficient pollinators of this species. A tritrophic syndrome, therefore, seems to have evolved involving plant (flower)–pollinator and predator (spiders)–pollinators interactions. The communication deals with the incidence of spiders’ interaction with Cleome through tritrophism i.e., plant–pollinator–predator relationship.

Increasing species sampling in chelicerate genomic-scale datasets provides support for monophyly of Acari and Arachnida

Chelicerates are a diverse group of arthropods, represented by such forms as predatory spiders and scorpions, parasitic ticks, humic detritivores, and marine sea spiders (pycnogonids) and horseshoe crabs. Conflicting phylogenetic relationships have been proposed for chelicerates based on both morphological and molecular data, the latter usually not recovering arachnids as a clade and instead finding horseshoe crabs nested inside terrestrial Arachnida. Here, using genomic-scale datasets and analyses optimised for countering systematic error, we find strong support for monophyletic Acari (ticks and mites), which when considered as a single group represent the most biodiverse chelicerate lineage. In addition, our analysis recovers marine forms (sea spiders and horseshoe crabs) as the successive sister groups of a monophyletic lineage of terrestrial arachnids, suggesting a single colonisation of land within Chelicerata and the absence of wholly secondarily marine arachnid orders.

Multiple intraguild predators reduce mortality risk of a mutual agricultural pest prey in simple, but not in complex, experimental settings

AbstractMultiple predator species that coexist with each other and their mutual prey can have combined effects on prey mortality that are similar to the sum of each predator's individual impact (linear effects), greater than the sum of each predator's individual impact (risk enhancement), or less than the sum of each predator's individual impact (risk reduction). Understanding multiple predator effects is important to determine the impact of predators on pest prey in agroecosystems. If two predators share the same broad spatial domain and hunting mode and engage in intraguild predation, then their combination is expected to result in risk reduction for a mutual prey. We tested this hypothesis using both additive and replacement experimental designs on two species of generalist wolf spider predators (Tasmanicosa leuckartii and Hogna crispipes) that hunt in the same domain, and a mutual insect prey (cotton bollworm Helicoverpa armigera). We used two types of enclosures: a small simple laboratory enclosure, and a larger more complex cotton plant enclosure. We found that in the small simple laboratory enclosures, the presence of two spiders led to risk reduction of Helicoverpa larva mortality as expected, but in larger more complex cotton plant enclosures the presence of both species resulted in linear effects rather than risk reduction on Helicoverpa mortality. Furthermore, intraguild predation did not change multiple predator effects in laboratory or plant enclosures. This study has implications for managing arthropod predators in agroecosystems; contrary to predictions of ecological frameworks, coexistence of predators that share the same hunting mode and hunting domain may not lead to risk reduction on a mutual prey in more complex environments, where encounters among predators can be lower. Conservation of multiple predators of a single guild can play an essential role on biological control of insect pests.

A possible role of decorations in spiderwebs as protection devices that distract predators

Several functions have been proposed for silk decorations (i.e., stabilimenta) in spiderwebs. One hypothesis is that web decorations protect spiders from predators, either by concealing the spiders, physically shielding them, or by deflecting predatory attacks. This study uses data gathered in opportunistic manner when studying the behavior of Stenolemus giraffa, an assassin bug that preys almost exclusively on web-building spiders. Stenolemus giraffa approach orb spiders on foot, and usually capture the spiders at the hub region of the web. When pursuing spiders, S. giraffa routinely tap the web with their antennae, and also tap the spiders prior to attacking them. The observations available from this study suggest that S. giraffa got “distracted” momentarily by the decorations in the webs of Purumitra sp. (Uloboridae) and Argiope katherina (Araneidae). In some instances, the assassin bugs tapped these structures for several seconds or minutes instead of tapping the adjacent spiders. In interactions with A. katherina, S. giraffa was more successful at capturing the spiders when the webs lacked decorations; however, sample sizes are small (this could not be tested for Purumitra sp. because only one web lacked decorations). Finally, some of the spiders detected S. giraffa tapping the decorations or that had begun tapping the spiders and that had interrupted this behavior to tap the decorations. The data available suggest that, for S. giraffa, the decorations in these webs interfered with the process of locating the spiders. If further experiments corroborate this idea, this information would be in accord with Hingston’s (1927) hypothesis that web decorations can confuse spider predators.

A routing algorithm for region division based on virtual spider web model

A disjoint multipath routing algorithm based on region division is proposed to resolve problems such as potential “hot area” around the sink node and path instability caused by frequent movement of routing nodes in the mobile wireless sensor network. This paper first improves the regional division model of the whole network by learning from the predation of spiders, and increases the number of nodes in the inner area by enlarging the width of the inner ring to alleviate the “hot area” problem. Then, three modes based on distance priority, angle priority, and weight priority are proposed to ensure the independence between the paths when generating the disjoint multipath of the mobile node in a certain divided area. Meanwhile, the method of selecting “borrowing node” with minimum weights is adopted to ensure the effectiveness of the path and deal with the path link break problem. Simulation experiments show that the proposed algorithm has a lower packet loss rate and path failure rate than EM-GMR and AGEM algorithms, which effectively prolongs the lifetime of the entire network and is more applicable to networks with dense nodes.

Bionics design and dynamics analysis of space webs based on spider predation

A new bionic space debris removal device, inspired by the spider predation, is designed in this paper, which consists of flexible webs, central hub, traction mass and rotating mechanism. Firstly, the concept of bionic space debris removal and corresponding system design are described in detail. Secondly, the dynamic models of spin deployment and collision are derived and foumulated respectively. Thirdly, a finite element analysis is presented to simulate the dynamic characteristics of the spinning webs deployment process. In addition, a finite element model of the webs is developed for structural modal analysis. Finally, a number of collision simulation analysis are carried out using finite element method and propagation of small disturbances along the tether are demonstrated via numerical simulations. The simulation results effectively reflect that the motion characteristics of the large deformation and large displacement in the process of capturing the target. Furthermore, it show that the proposed novel bionic flexible web can meet design requirements for a space debris removal system.

Will like replace like? Linking thermal performance to ecological function across predator and herbivore populations.

The inability of species to adapt to changing climate may cause ecological communities to disassemble and lose ecological functioning. However, theory suggests that communities may be resilient whenever populations within species exhibit variation in thermal plasticity or adaptation whereby thermally tolerant populations replace thermally sensitive ones. But will they maintain the functional roles of the populations being replaced? This study evaluated whether "like replaces like" functionally by measuring how four populations of a grasshopper herbivore and its co-occurring spider predator cope with environmental warming. The study occurred across a latitudinal gradient bounded by southerly, warmer Connecticut and northerly, cooler New Hampshire, USA. The study compared the survival rates, thermal performance, habitat usage, and food chain interactions of each grasshopper and spider population between its home field site (field of origin) and a Connecticut transplant site, and the native Connecticut population. Three grasshopper populations exhibited physiological plasticity by adjusting metabolic rates. The fourth population selected cooler habitat locations. Spider populations did not alter their metabolism and instead selected cooler habitat locations, thereby altering spatial overlap with their prey and food chain interactions. Grasshopper populations that coped physiologically consumed plants in different ratios than the fourth population and the Connecticut population. Hence, "like may not replace like" whenever populations adapt physiologically to warming.

Populasi Serangga Hama dan Artropoda Predator pada Padi Rawa Lebak Sumatera Selatan yang Diaplikasikan Bioinsektisida dari Beauveria bassiana dan Insektisida Sintetik

Hanif et al, 2019. Population of Pest Insects and Predatory Arthropods Inhabiting Freshwater Swamp Rice of South Sumatra Treated with Bioinsectide of Beauveria bassiana and a Synthetic Insecticide. JLSO (8)1:31-38.Entomopathogenic fungi, Beauveria bassiana, could kill various species of insect pests, but their impact on predatory arthropods needs to be studied. The aim of this study was to compare population of pest insects and predatory arthropods inhabiting rice sprayed with bioinsecticide of B. bassiana and conventional rice field using a synthetic insecticides. Bioinsecticide was made from conidia of B. bassiana and sprayed on rice canopy. The plot of conventional farmers was sprayed with synthetic insecticides made from Abamektrin. The results showed that the application of bioinsecticide of B. bassiana was not proven to reduce the pest insect population. The abundance of natural enemies of pest insects, such as spiders and predatory insects was also more abundant in plots sprayed with bioinsecticide than conventional plots that used synthetic insecticide. The synthetic insecticides have been shown to reduce the abundance of predatory insects and spiders. Bioinsecticides containing carrier of liquid compost were proven to increase the growth and development of rice, which was an increase in the number of rice tillers per clump in plots applied by bioinsecticide. Thus, B. bassiana of bioinsecticide with liquid compost carrier material was safer and could maintain the abundance of predatory arthropods and increased rice growth.

Pest control potential of four predatory spiders from soybean fields

Pest control potential of four predatory spiders from soybean fields

THE POPULATION OF WHITE-BELLIED PLANTHOPPERS AND THEIR NATURAL ENEMIES: THE NEW PEST OF CORN IN LAMPUNG

The Population of White-Bellied Planthoppers and their Natural Enemies: the New Pest of Corn in Lampung. The white-bellied planthoppers (Stenocranus pasificus), hereinafter referred to as WBP, as new exotic pests in Lampung have the poten-tial to reduce corn production and threaten national food sovereignty. Therefore, population of the pest needs to be managed to prevent the outbreaks. However, there is still limited information on the bio-ecology of WBP. Thus, this research was conducted to: 1) study the population growth pattern of WBP on various corn cultivars and 2) document the natural enemies of WBP. This research was carried out from May to December 2017with a survey method on several corn fields in South Lampung and planting trial on an experimental field of Faculty of Agriculture, Universitas Lampung planted with 3 corn cultivars, i.e. Madura, P-27 and NK which were arranged in randomized complete block design with three replications. The results of the research showed: 1) there were two peaks of population density observed during plant growth. The peak of adult stage of macroptera population density occurred at 17 and 53 days after planting (dap), the highest number of leaves with oviposition mass was observed at 24 and 65 dap, while the peak of population density of nymph stage and adult stage of brachiptera occurred at 31 and 75 dap; 2) Natural enemies of WBP included 9 orders, classified as specialist predators of mirid bugs (Cyrtorhynus) and rove beetles (Paederus), and generalist predators of spiders (Araneae) and lady beetles (Coccinellidae). The population of specialist predators was fluctuated depending on WBP population, while the population of generalist predators was varied.

Contrasting indirect effects of an ant host on prey–predator interactions of symbiotic arthropods

Indirect interactions occur when a species affects another species by altering the density (density-mediated interactions) or influencing traits (trait-mediated interactions) of a third species. We studied variation in these two types of indirect interactions in a network of red wood ants and symbiotic arthropods living in their nests. We tested whether the ant workers indirectly affected survival of a symbiotic prey species (Cyphoderus albinus) by changing the density and/or traits of three symbiotic predators, i.e., Mastigusa arietina, Thyreosthenius biovatus and Stenus aterrimus, provoking, respectively, low, medium and high ant aggression. An ant nest is highly heterogeneous in ant worker density and the number of aggressive interactions towards symbionts increases with worker density. We, therefore, hypothesized that varying ant density could indirectly impact prey-predator interactions of the associated symbiont community. Ants caused trait-mediated indirect effects in all three prey-predator interactions, by affecting the prey capture rate of the symbiotic predators at different worker densities. Prey capture rate of the highly and moderately aggressed spider predators M. arietina and T. biovatus decreased with ant density, whereas the prey capture rate of the weakly aggressed beetle predator S. aterrimus increased. Ants also induced density-mediated indirect interactions as high worker densities decreased the survival rate of the two predatory spider species. These results demonstrate for the first time that a host can indirectly mediate the trophic interactions between associated symbionts. In addition, we show that a single host can induce opposing indirect effects depending on its degree of aggression towards the symbionts.

The significance of prey avoidance behavior for the maintenance of a predator color polymorphism

Why do some animals have variable color patterns? We show that honeybee behavior can favor the persistence of red, yellow and white patterns in spider predators. Although it is well known that predators can promote morphological diversity in their prey, our study is one of the first to show that the reverse might also happen. Our results add to our understanding of the ecological processes shaping the appearance of animals in natural populations.

Temporal variation in bottom-up and top-down effects differ among herbivores with different seasonality

How variations in the strength of bottom-up and top-down forces are mediated by life-history trait differences of insect herbivores is an important but underexplored topic in ecology. Here, we implemented a factorial experiment manipulating plant quality by nitrogen fertilization and attack rates of parasitoids and spiders, respectively. We used sticky traps and mesh barriers in a salt marsh system to examine bottom-up and top-down effects on populations of three hemipteran sap-feeding monophagous species of Phragmites australis with different seasonality. The species included Chloriona alaica and Stenocranus matsumurai most abundant in spring and autumn, respectively, and Dimorphopterus pallipes abundant in both summer and autumn. Fertilization increased the density of S. matsumurai but had no effect on C. alaica and D. pallipes. Its negative effects on densities of the latter two species were even observed in earlier months. On the other hand, parasitoid removal not only increased abundance of all three herbivores, but also reduced the culm diameter, shoot height and biomass of P. australis, suggesting a trophic cascade. The main effects of parasitoid removal were greatest in months when those herbivores had their peak densities. In contrast, spider removal only affected the abundance of S. matsumurai with the greatest effect in September. Our results indicate that parasitoids have strong top-down effects on populations of insect herbivores in P. australis-dominated salt marshes and the strength of their effects is positively correlated with the host density. Furthermore, effects of plant quality and spider predation are more varied among herbivores with different seasonality.

Bumblebees Express Consistent, but Flexible, Speed-Accuracy Tactics Under Different Levels of Predation Threat.

A speed-accuracy trade-off (SAT) in behavioural decisions is known to occur in a wide range of vertebrate and invertebrate taxa. Accurate decisions often take longer for a given condition, while fast decisions can be inaccurate in some tasks. Speed-accuracy tactics are known to vary consistently among individuals, and show a degree of flexibility during colour discrimination tasks in bees. Such individual flexibility in speed-accuracy tactics is likely to be advantageous for animals exposed to fluctuating environments, such as changes in predation threat. We therefore test whether individual speed-accuracy tactics are fixed or flexible under different levels of predation threat in a model invertebrate, the bumblebee Bombus terrestris. The flexibility of speed-accuracy tactics in a foraging context was tested in the laboratory using a “meadow” of artificial flowers harbouring “robotic” crab spider predators. We found that while the ranking of bees along the speed and accuracy continuums was consistent across two levels of predation threat, there was some flexibility in the tactics used by individual bees – most bees became less accurate at colour discrimination when exposed to predation threat when flower types were rewarding. The relationship between decision speed and accuracy was influenced by predator detectability and the risk associated with making incorrect choices during the colour discrimination task. Predator crypsis resulted in a breakdown in the relationship between speed and accuracy, especially when making an incorrect floral choice incurred a distasteful quinine punishment. No single speed-accuracy tactic was found to be optimal in terms of foraging efficiency under either predation threat situation. However, bees that made faster decisions achieved higher nectar collection rates in predator free situations, while accurate bees achieved higher foraging rates under predation threat. Our findings show that while individual bees remain relatively consistent in terms of whether they place greater emphasis on speed or accuracy under predation threat, they can respond flexibly to the additional time costs of detecting predators.

Fortuitous Biological Control of InvasiveAleurocybotus occiduuson Sugarcane in Western Mexico

The whitefly, Aleurocybotus occiduus (Russell) (Hemiptera: Aleyrodidae), invaded western Mexico in 2006, attacking several gramineous crops and weeds in the families Poaceae and Cyperaceae. The objective of this study was to determine the impact of native natural enemies on A. occiduus on sugarcane near Los Mochis during 2006–2011. Peak abundance of A. occiduus occurred during August–September, coinciding with warm temperature and precipitation in the region. A series of native parasitoids and predators effectively regulated A. occiduus since its invasion, gradually decreasing pest abundance from 18.46 nymphs per leaf in 2006 to 0.04 in 2011. Total parasitism varied from 33 to 100% by five parasitoids, including two new species: Encarsia longitarsis Myartseva and Metaphycus cerealis Myartseva & Ruiz. Of all arthropod predators collected, 87% were spiders in the families Araneidae, Licosidae, Oxyopidae, Salticidae, Theridiidae, and Thomisidae. Insect predators were less abundant, including several species of Chrysopidae, Melyridae, Coccinellidae, Anthocoridae, Lygaeidae, Reduviidae, and Mantidae. Both parasitoids and spider predators showed density dependence with A. occiduus. This is a case of fortuitous biological control, because an exotic insect pest was regulated by native natural enemies