Predatory Rate Research Articles

Predatory Potential of Nymphal Odonates on Aedes aegypti Developing in Freshwater and Brackish Water Habitats.

Aedes aegypti, the primary vector of dengue, undergoes preimaginal development in brackish water (BW). However, dengue vector control exclusively targets freshwater (FW) habitats. The present study evaluated the predatory efficacy of nymphal odonates that can develop in both FW and BW. Nymphs of three damselfly and three dragonfly species from FW and BW habitats were identified and acclimatized to FW (<0.5 gL-1 salt) and BW (10 gL-1 salt) mesocosm conditions. The experiment was repeated nine times with nine different individual predators per species under both salinity conditions. One hundred L3 Ae. aegypti from FW and BW laboratory colonies were introduced to determine the predatory rate (PR) and clearance rate (CR) after 24, 48, and 72 h, and one hundred L3 larvae were introduced every 24 h. The dragonfly nymph Hydrobasileus croceus and the damselfly nymph Paracercion hieroglyphicum showed the highest PR and CR under both rearing conditions at all times. However, damselfly and dragonfly nymphs significantly (p < 0.05) differed in their CR under both FW and BW conditions. Thus, all six odonate species have predatory potential and this suggests that they could be used as biological control agents to eliminate preimaginal stages of Ae. aegypti developing in both FW and BW habitats.

Lethal competition on joint predators during suppressing brown planthopper population

Joint predator is one technique to control brown planthopper (Nilaparvata lugens) in the rice field by combining two or more predator species having a positive interaction. This study aims to determine the effect of joint predator density (Pardosa pseudoannulata and Phidippus sp) on competition and its predatory rate in suppressing the N.lugens population. The study used a completely randomized design (CRD) by combining P. pseudoannulata or Pp (1,2,3 individuals) and Phidippus sp or Ps (1,2,3 individuals) to become Pp1Ps1, Pp1Ps2, Pp1Ps3, Pp2Ps1, Pp2Ps2, Pp2Ps3, Pp3Ps1, Pp3Ps2, Pp3Ps3. The parameters observed were predation rate, bodyweight, mortality of both predators, and competition model. The results showed that the composition difference between P. pseudoannulata and Phidippus sp affected on competition model and the predation. The predation rate of joint predators at different densities ranged from 40.4 – 47.0 individuals of N.lugens (80.8-94.0%) in one-day observation, and they consumed all prey until the third day’s observation. The highest predation rate occurred for Pp3Ps3, but it was assumed it was not safe because of cannibalism and lethal competition. The Pp1Ps2 composition of joint predators was classified as safe, with 0 and 0.2 individuals’ mortalities and followed by draw competition between two predators.

Behavioral Interactions between Bacterivorous Nematodes and Predatory Bacteria in a Synthetic Community.

Theory and empirical studies in metazoans predict that apex predators should shape the behavior and ecology of mesopredators and prey at lower trophic levels. Despite the ecological importance of microbial communities, few studies of predatory microbes examine such behavioral res-ponses and the multiplicity of trophic interactions. Here, we sought to assemble a three-level microbial food chain and to test for behavioral interactions between the predatory nematode Caenorhabditis elegans and the predatory social bacterium Myxococcus xanthus when cultured together with two basal prey bacteria that both predators can eat—Escherichia coli and Flavobacterium johnsoniae. We found that >90% of C. elegans worms failed to interact with M. xanthus even when it was the only potential prey species available, whereas most worms were attracted to pure patches of E. coli and F. johnsoniae. In addition, M. xanthus altered nematode predatory behavior on basal prey, repelling C. elegans from two-species patches that would be attractive without M. xanthus, an effect similar to that of C. elegans pathogens. The nematode also influenced the behavior of the bacterial predator: M. xanthus increased its predatory swarming rate in response to C. elegans in a manner dependent both on basal-prey identity and on worm density. Our results suggest that M. xanthus is an unattractive prey for some soil nematodes and is actively avoided when other prey are available. Most broadly, we found that nematode and bacterial predators mutually influence one another’s predatory behavior, with likely consequences for coevolution within complex microbial food webs.

Compatibility of degummed soybean and babassu oils with the generalist predatory mite Typhlodromus (Anthoseius) ornatus (Acari: Phytoseiidae) preying on Aceria guerreronis (Acari: Eriophyidae)

ABSTRACT Typhlodromus (Anthoseius) ornatus Denmark & Muma (Acari: Phytoseiidae) is one of the predatory mites associated with the coconut mite Aceria guerreronis (Acari: Eriophyidae), considered a severe pest of coconut plantations worldwide. In addition to predatory mites, vegetable oils such as degummed soybean and babassu oils have shown high efficiency in controlling A. guerreronis. Here, we evaluated the effects of degummed soybean and babassu oils on the functional response and oviposition of T. (A.) ornatus preying on A. guerreronis. Exposure to the tested oils did not alter either the functional response or the attack rate of T. (A.) ornatus. The variation in prey consumption with the exposure to vegetable oils did not differ from the control, although degummed soybean oil led to higher consumption compared to babassu oil. In addition, prey handling time and peak consumption were negatively affected by the exposure to babassu oil. The number of eggs laid by the female of T. (A.) ornatus at intermediate prey density decreased under exposure to degummed soybean oil. Overall, our results indicate that the tested oils are generally compatible with T. (A.) ornatus as they do not alter predatory responses but oviposition rate is affected by degummed soybean oil.

Potential for the Postharvest Biological Control of Phthorimaea operculella (Lepidoptera, Gelechiidae) by Blattisocius tarsalis (Mesostigmata, Blattisociidae)

Phthorimaea operculella is one of the most important pests causing damage to stored potatoes. In this work, the effect of temperature (at 10, 20 and 30 °C) on the predation of pest eggs by Blattisocius tarsalis was studied in the laboratory. In addition, the effect of three predatory release rates on two pest densities was studied under microcosm conditions. The results showed that B. tarsalis maintains its predatory capacity at low temperatures (10 °C), obtaining an efficiency of 49.66 ± 5.06% compared to the control. In turn, at 20 °C, a maximum efficacy of 78.17 ± 4.77% was achieved, very similar to that presented at 30 °C (75.57 ± 4.34%). Under microcosm conditions and at low pest density (10 eggs/container), the mortality due to the mite was 96.97 ± 3.03%, 81.82 ± 8.84%, and 84.85 ± 8.30%, respectively, for the three predatory release rates (5, 10 or 20 mites/container). At the high infestation level, the pest control ranged from 61.54 ± 9.21% to 92.31 ± 2.74%, depending on the predatory release rate. The results obtained show that B. tarsalis could be a relevant control agent against P. operculella under non-refrigerated potato storage conditions, as well as in the first stages of their storage under refrigerated conditions.

Comparison of the predation capacities of two soil-dwelling predatory mites, Gaeolaelaps aculeifer and Stratiolaelaps scimitus (Acari: Laelapidae), on three thrips species

• Predation rate of two soil-dwelling predatory mites compared. • Predation activity of Gaeolaelaps aculeifer were higher than Stratiolaelaps scimitus. • Predatory mite species did not discriminated against a specific thrips developmental stage. • Soil-dwelling predatory mites have a broad thrips prey range. Soil-dwelling predatory mites are natural enemies of various soil pest insects and mites. Both Gaeolaelaps aculeifer (Canestrini) and Stratiolaelaps scimitus (Womersley) are commercialized natural enemies of thrips, but there is little information on the predation rate of these predatory mites on different thrips species. We compared their predation capacities on three thrips species, Frankliniella occidentalis, F. intonsa , and Thrips palmi, which are major pests of various horticultural plants. The predatory rate of G. aculeifer was higher than that of S. scimitus. Both predator species fed on more T. palmi thrips than F. occidentalis or F. intonsa thrips , which may be attributable to the smaller body size of T. palmi than the other thrips . Predation rates of female adults were 2.6–2.8 times higher than those of deutonymphs in both species. Predation rates were not separated according to the various developmental stages (i.e., second instar larva, pupa, or adult) of thrips; however, deutonymphs fed on fewer adults than larvae or pupae of F. occidentalis . Our results suggest that both G. aculeifer and S. scimitus are active predators that can prey during any of their developmental stages and on any species of thrips tested.

POLYMORPHISM OF RHYNOCORIS MARGINATUS (FAB.) (HETEROPTERA : RUDUVIIDAE) ON THE BIOLOGY, BIOLOGICAL CONTROL POTENTIAL

ABSTRACT To know the influence of polymorphism of Rhynocoris marginatus (Fab.) on the biology, biological control pontential and molecular profile were recorded in the following partners : N male + N female; N male + S female, N male + NS female, NS male + NS female and S + NS female under laboratory conditions. Offspring produced by the S + NS female partners developed quickly having minimum body weight and size and egg hatching percentage, maximum relative growth rate both in first instars and adults, maximum survival rate (82.5 ± 3.50%), male biased sex ratio (0.23). In general, the predatory rate was increased when the prey deprivation period increased from 24 hrs to 72 hrs, third instars to adults. Molecular analysis studies revealed that the total free amino acid was high in N adult morphs. No unique DNA sequence was observed among the morphs of R. marginatus. Among the polymorphic R. marginatus, N male + N female; N male + S female, N male + NS female, NS male + NS female and S + NS, approaching time was also decreased in the latter instars and adult, the biological control potential is highly observed in 96 hrs starved N+N adults showed minimum approaching time, handling time, and high predatory rate. Among the experimental morphs the weight gain was maximum in N+N and minimum weight gain was observed among the morphs of SNS. Minimum total nymphal developmental period, least body weight, survival rate were recorded among the offsprings produced by S+NS, NS+NS and N+NS partners.

Scrutinizing predator journals in pharmacology and calculating their predatory rate.

BACKGROUND:As the list of predatory journals is burgeoning, the researchers should have knowledge of calculating the predatory rate (PR) for the journals, in which they aim to publish their work and self-guard them from publishing in bogus journals.AIM AND OBJECTIVES:Our aim is to find out the predatory rate for various Pharmacology journals.MATERIALS AND METHODS:Here, we have examined the recently updated list (in 2017) of standalone predatory journals created and maintained by Beall, pertinent to all auspices of pharmacology including pharmacy, pharmaceutical, and pharmacognosy. The PR of various journals was calculated.RESULTS:Of 131 journals, pertinent to the pharmacology field, 45.03% of them had the PR between 0.72 and 0.84. 98.5% of journals were classified as predatory, whereas only 2 (1.53%) journals were classified in the category of predatory practice.CONCLUSION:It should be an eye-opener to the researchers, and they should deliberately select the journals to get real recognition of their work.

Effects of Entomopathogenic Fungi on the Biology of Spodoptera litura (Lepidoptera: Noctuidae) and its Reduviid Predator, Rhynocoris marginatus (Heteroptera: Reduviidae).

Entomopathogenic fungi (EPFs), Isaria fumosorosea and Beauveria bassiana, are efficient biological agents in the management of multiple arthropod pests. In this study, the effects of both EPF species on various life stages of Spodoptera litura (F.) (Lepidoptera: Noctuidae) and its natural enemy Rhynocoris marginatus (Fab.) (Hemiptera: Reduviidae) were determined under laboratory conditions. I. fumosorosea significantly (P < .05) reduced the growth rate of the third and fourth instar larvae of S. litura. For relative consumption rate (RCR), the maximum impact was recorded for I. fumosorosea, which reduced the RCR of the larvae. The larvae of S. litura treated with I. fumosorosea showed significantly lower efficiency of conversion of ingested food (ECI) and the larval mortality rate (58.0%) was also higher compared with B. bassiana (33.3%). Similarly, I. fumosorosea had a significant effect on the pupal formation of S. litura; however, no significant effect was found on adult emergence percentage. To determine the effect of EPF-infected prey on the adult predator, their handling time, predatory rate, consumption rate, and the survival rate were recorded. No significant effect of EPF species on the predation rate was found. Furthermore, no significant difference was found in the survival rate of predators fed on either EPF-infected prey or healthy larvae. The interaction of these EPFs with a reduviid predator suggested that both EPF species, especially I. fumosorosea, could be used together with the predator to boost the biological control of S. litura in commercial crops.

Asymmetries in responses of commercial banks in a transitional economy to countercyclical monetary policy: The case of Romania

The empirical results of this study reveal the following interesting characteristics of the Romanian banking sector over the December 1993 through August 2017 period. First, the spread between the lending-Central Bank’s discount rates was stable and adjusted to its long-run threshold asymmetrically. Second, lending institutions respond faster to contractionary than expansionary countercyclical monetary policy actions. This empirical finding suggests that Romanian commercial banks exhibit predatory rate setting behavior, which is consistent with those of their counterparts in advanced and emerging economies. Third, lending institutions respond to countercyclical monetary policy and the Romanian Central Bank authority effectively utilizes monetary policy to manage the economy as evidenced by the short-run dynamic and long-run Granger-causality from the discount rate to the banks’ lending rate. With respect to the time lags of the Romanian monetary policy found within the banking sector, the empirical results suggest that it takes almost two years for the lending rate to adjust to a monetary policy action completely.

Predatory Journals Spamming for Publications: What Should Researchers Do?

In the internet era spam has become a big problem. Researchers are troubled with unsolicited or bulk spam emails inviting them to publish. However, this strategy has helped predatory journals hunt their prey and earn money. These journals have grown tremendously during the past few years despite serious efforts by researchers and scholarly organizations to hinder their growth. Predatory journals and publishers are often based in developing countries, and they potentially target researchers from these counties by using different tactics identified in previous research. In response to the spread of predatory publishing, scientists are trying to develop criteria and guidelines to help avoid them-for example, the recently reported "predatory rate". This article attempts to (a) highlight the strategies used by predatory journals to convince researchers to publish with them, (b) report their article processing charges, (c) note their presence in Jeffrey Beall's List of Predatory Publishers, (d) rank them based on the predatory rate, and (e) put forward suggestions for junior researchers (especially in developing counties), who are the most likely targets of predatory journals.

Ranking predatory journals in dermatology: distinguishing the bad from the ugly.

The scientific community depends on high-quality peer-reviewed research, which is being polluted with pseudoscience published in fake journals that have exploited the open-access model. This "predatory publishing" has made its way into the field of dermatology. In a recent study, we identified and listed these journals. The "predatory rate" was calculated for 76 journals in order to rank the journals based on specific criteria associated with unethical publishing. Of the 76 journals, 89.5% were classified as predatory journals and the remaining as journals involved in predatory practices. The field of dermatology is not immune to predatory publishers. This study validates Beall's list as well as other previous studies. Strategies to a solution include spreading awareness throughout academic institutions and dermatology departments as well as avoiding publishers that are involved in predatory practices. However, some journals may be able to make necessary adjustments and become legitimate contributors to the field.

Effect of Habitat Modifications on Predation Potential of &lt;i&gt;Anisops sardea&lt;/i&gt; (Hemiptera: Notonectidae) against Larvae of Culex vishnui, Vector of Japanease Encephalitis

To prevent emergence of insecticide resistance in vector population & biological magnification of toxic insecticides through food chain, more attention is now put on application of biological control system to reduce the population of vectors. Present study was carried out to assess the effect of habitat modifications on the predatory ability of Anisops sardea (Hemiptera: Notonectidae) against immature of Culex Vishnui (Diptera: Culicidae) group of mosquitoes in laboratory and semi-field bioassay.To study the effect of habitat modifications, laboratory based predatory experiments were carried with A. sardea as predator and Cx.vishnui group of mosquitoes as prey species. To determine prey preference of predator species, predatory experiment was done in presence of mosquitoes belongs to different genera. For a long-term study on predation rate, for 15 consecutive days, 10 adult individuals of A. sardea were kept in a plastic bucket of 20 L capacity in open natural condition and number of mosquito larvae consumed/per day was calculated.Result of single factor ANOVA analysis revealed that habitat modifications have significant effect on the predatory rate of A sardea as calculated F value (34.10) is significantly higher than table value (F crit =2.156). Pair wise ‘t test’ revealed significant variations in the predation rate when different habitat combinations were analyzed. Results of selectivity index, niche breadth and food breadth were also evaluated. Long term bioassay in semi-field condition revealed that predatory rates were almost similar throughout the study period.Considering the habitat specificity, prey preference and the rate of predation in semi field condition, it can be concluded that A. sardea can be used as potential biological control agent against Culex Vishnui group of mosquitoes.

Predatory exchange rate misalignments and the imbalance of the multilateral trade system: why this should be a WTO prerogative?

A prática de desalinhamentos cambiais predatórios possui papel de significativa importância para o comércio internacional, uma vez que fere a lógica do multilateralismo. Dada a possibilidade de praticar tais desalinhamentos para sobrepujar decisões fruto de negociações no âmbito da OMC, quais os papéis do FMI e da OMC na abordagem desse problema? Por quais motivos essa seria uma prerrogativa da OMC? O objetivo principal desse artigo é fomentar o atual debate sobre a questão, apresentando os principais argumentos a favor de uma ação mais assertiva da OMC no tratamento dos desalinhamentos cambiais predatórios.Palavras-chave: WTO; desalinhamentos cambiais predatórios; multilateralismo.

Stage preference and functional response of Rhynocoris longifrons (Stål) (Hemiptera: Reduviidae) on three hemipteran cotton pests

In this work, the stage preference and functional response of the indigenous reduviid bug Rhynocoris longifrons feeding on five different densities of the cotton aphid Aphis gossypii, Phenacoccus solenopsis, and Dysdercus cingulatus was examined in Petri dish arenas containing cotton leaves under laboratory conditions. The reduviid predator exhibited a Type II functional response at all hemipteran pests evaluated when data were fit to Holling's disc equation. Predatory rate gradually increased while the predator grew older and adults consumed maximum number of D. cingulatus and P. solenopsis. An opposite trend was observed, while the reduviid was provided with Aphis gossypii. The rate of attack on P. solenopsis was quite low but fairly consistent, with the different life stages of the predator generally more effective. Further investigation of the biological control potential of R. longifrons against cotton pests under pot and controlled filed should be done due to the predator's ability to kill adult stages of all prey species evaluated. These results indicated that R. longifrons could eat more aphids at high prey densities; however, predators also considerably reduced other cotton pests too so it could be considered a prospective candidate for use as a commercial biological control agent for cotton hemipteran pests in India.

Abstracts of the 17th International Symposium on Bioluminescence and Chemiluminescence ‐ (ISBC 2012)

WARNING : The light-emitting molecular structures responsible for the chemiluminescence and fluorescence phenomena are not necessarily the same!

Parasitism may enhance rather than reduce the predatory impact of an invader

Invasive species can have profound impacts on communities and it is increasingly recognized that such effects may be mediated by parasitism. The 'enemy release' hypothesis posits that invaders may be successful and have high impacts owing to escape from parasitism. Alternatively, we hypothesize that parasites may increase host feeding rates and hence parasitized invaders may have increased community impacts. Here, we investigate the influence of parasitism on the predatory impact of the invasive freshwater amphipod Gammarus pulex. Up to 70 per cent of individuals are infected with the acanthocephalan parasite Echinorhynchus truttae, but parasitized individuals were no different in body condition to those unparasitized. Parasitized individuals consumed significantly more prey (Asellus aquaticus; Isopoda) than did unparasitized individuals. Both parasitized and unparasitized individuals displayed Type-II functional responses (FRs), with the FR for parasitized individuals rising more steeply, with a higher asymptote, compared with unparasitized individuals. While the parasite reduced the fitness of individual females, we predict a minor effect on population recruitment because of low parasite prevalence in the peak reproductive period. The parasite thus has a large per capita effect on predatory rate but a low population fitness effect, and thus may enhance rather than reduce the impact of this invader.

Biological control potential of artificial diet and insect hosts reared Rhynocoris marginatus (Fab.) on three pests

Biological control potential of insect hosts as well as artificial diet reared Rhynocoris marginatus (Fab.) (Heteroptera: Reduviidae) life stages on Dysdercus cingulatus (Fab.), Spodoptera litura (Fab.) and Corcyra cephalonica Stainton in terms of approaching time, handling time, and predatory rate (weight gain and number of prey consumed) were evaluated under laboratory conditions. Results revealed that the particular stage of the predator preferred the desired stage of the pests studied. Moreover, younger reduviid preferred younger prey and vice versa. The biological control potential of the reduviid showed that, irrespective of the preys offered, females consumed greater numbers of prey than the males. Among the three prey tested, S. litura was the most preferred prey followed by D. cingulatus and C. cephalonica. Both the handling time and weight gain differed among the life stages of the reduviid reared with an artificial diet and insect prey.

Development and Recruitment ofMisumenops pallidus(Keyserling) (Araneae: Thomisidae), and Its Synchronicity with Three Potential Prey Species in Soybean Cultures from Argentina

ABSTRACT: Misumenops pallidus life cycle and recruitment were studied under both laboratory and field conditions during two consecutive years. The life cycle included the egg stage, seven or eight juvenile instars and the adult stage. The first three instars developed within the egg sac, while the others developed as free-living individuals. Total body length increased from 3.2mm in the 3rd instar up to 14mm in adult females in average, and from 3.2mm up to 9mm in males. Predatory rate increased according to growth and maturity in females (females would consume 81% of all prey in the adult stage). Longevity of males and females as adults averaged 69.2 (± 30.76) and 161.3 (± 45.4) days, respectively. The developmental time from IV instar (the first free living instar) to the adult stage (114.2 ± 22.83 days) was very variable and long, suggesting that all IV instars of M. pallidus found in 94% of all sampling dates would represent different cohorts of the same parental generation. Three of potential prey: R...

PREY DEPRIVATIONS ON THE PREDATORY RATE OF CANTHECONA FURCELLATA WOLFF. (HEMIPTERA: PENTATOMIDAE) ON POPLAR DEFOLIATOR, CLOSTERA FULGURITA WALK

ABSTRACT Laboratory experiments were conducted to find out the impact of the prey, Clostera fulgurita Walk (Lepidoptera: Notodontidae) deprivation period on the feeding behavior and predatory rate of Canthecona furcellata Wolff (Hemiptera : Pentatomidae). Results revealed that prey consuming time, and predatory rate were gradually increased in accordance with the prey deprivation period and this predator could be used for the biological control agent of C. fulgurita. However more studies are necessary to recommend this predator as a biological control agent.