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"predatory insects"
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Bugs bugs bugs!
Describes the hunting activities of various bugs, including the praying mantis, wood ant, and dragonfly.
Book
Do Development and Diet Determine the Degree of Cannibalism in Insects? To Eat or Not to Eat Conspecifics
Cannibalism in insects plays an important role in ecological relationships. Nonetheless, it has not been studied as extensively as in other arthropods groups (e.g., Arachnida). From a theoretical point of view, cannibalism has an impact on the development of more realistic stage-structure mathematical models. Additionally, it has a practical application for biological pest control, both in mass-rearing and out in the field through inoculative releases. In this paper, the cannibalistic behavior of two species of predatory bugs was studied under laboratory conditions—one of them a generalist predator (strictly carnivorous), Nabis pseudoferus, and the other a true omnivore (zoophytophagous), Nesidiocoris tenuis—and compared with the intraguild predation (IGP) behavior. The results showed that cannibalism in N. pseudoferus was prevalent in all the developmental stages studied, whereas in N. tenuis, cannibalism was rarely observed, and it was restricted mainly to the first three nymphal stages. Cannibalism and intraguild predation had no linear relationship with the different cannibal–prey size ratios, as evaluated by the mortality rates and survival times, although there were variations in cannibalism between stages, especially for N. pseudoferus. The mathematical model’s implications are presented and discussed.
Journal Article
5 wild creature adventures! : a collection of five early readers /
A collection of five previously released Wild Kratts animal adventures.
Book
Relationships between predatory aquatic insects and mosquito larvae in residential areas in northern Thailand
In order to elucidate the poorly understood relationships between mosquito larvae and their predatory aquatic insects in urban and suburban areas of tropical Southeast Asia, where vector-borne diseases are prevalent, aquatic insects were sampled from 14 aquatic habitats in residential areas of Chiang Mai, northern Thailand, during the rainy season (July to November) in 2016. Correlations among biological variables, densities of major predatory aquatic insect groups (i.e., Odonata, Coleoptera, and Hemiptera: OCH group) in wetlands and artificial lentic habitats, and the density of mosquito larvae were analyzed. Among the sampled mosquito larvae, Culex spp. were the most abundant, and both OCH density and water quality were major determinants of Culex spp. density (rs = -0.302 and -0.396, respectively). Logistic regression analyses indicated that the probability of Culex spp. occurrence was significantly and negatively correlated with OCH density. Furthermore, high macrophyte abundance was associated with higher predator density, potentially reducing mosquito density. Hemipteran predators were most negatively correlated with Culex spp. density, regardless of whether macrophyte abundance was high or low (rs = -0.547 and -0.533, respectively). Therefore, hemipteran predators were the most important aquatic insect predators in the urban and suburban residential areas of Chiang Mai, Thailand, and OCH species, such as the hemipteran Micronecta scutellaris, could be used as biological control agents against mosquitoes in the region.
Journal Article
Mina
Mina est une mignonne petite souris blanche, qui habite dans un antre douillet et chaleureux dans lequel son père ne cesse de rapporter des trouvailles biscornues. Cette fois, c'est avec une joie non dissimulée qu'il lui présente ce qu'il croit être un écureuil, mais qui s'avère plutôt être un gigantesque chat noir et blanc! Son papa a beau lui dire qu'il n'y a aucune inquiétude à avoir, Mina ne peut s'empêcher de craindre cette énorme bête aux griffes acérées et au regard peu amène, qui prend énormément de place dans leur petite bulle. Si la cohabitation se passe plutôt bien au départ, le papa de Mina s'inquiète bientôt du fait que le félin ne manque pas. Que dira de tout cela le docteur appelé à la rescousse? [SDM].
Book
Diving beetle assemblages of flooded wetlands in relation to time, wetland type and Bti-based mosquito control
We investigated the abundance and taxonomic composition of the aquatic predatory insect fauna, with focus on adult diving beetles (Coleoptera: Dytiscidae), in eight temporary flooded wet meadows and two alder swamps in the River Dalälven floodplains, central Sweden from 2002 to 2006. Diving beetles are generalist predators and often abundant in various waters, including temporary wetlands. In the River Dalälven floodplains, recurrent floods induce massive hatching of flood-water mosquitoes (Diptera: Culicidae), which constitute a superabundant patchy and irregular food resource for aquatic predatory insects. Our aims were (1) to characterize the assemblage of adult diving beetles occurring in the wetlands during floods in relation to time and wetland type and (2) to evaluate the effect on the aquatic predator assemblage of strongly reducing the abundance of a potential prey, flood-water mosquito larvae with Bacillus thuringiensis var. israelensis (Bti) during floods. We found diving beetles to be the dominating aquatic predatory insect taxa in all 10 wetlands. There was a difference in Dytiscidae species richness but not in diversity between wet meadows and alder swamps after rarefaction. The cluster analysis based on dytiscid species and abundances showed very high similarities between the wetlands. The variance component analysis was unable to distinguish any factor that could explain more than 7.4% of the variation in the dytiscid species assemblages. The only effect of Bti-treatment against flood-water mosquito larvae, potential food for the predatory dytiscids, was a slight increase in abundance of the medium-sized dytiscid species. Our results are in accordance with previous studies, suggesting that irregular and recurrent flood dynamic structure the dytiscid fauna more than food limitations and environmental factors.
Journal Article
Body size and substrate association of littoral insects in relation to vegetation structure
Variation in substrate association types and maximum size of aquatic insects were studied in a vegetated littoral zone of three lake basins. The basins differed from each other in trophic status, biomass of benthivorous fish, and abundance of macrophytes. Four types of substrate association - swimmers, crawlers, semisessiles and burrowers, respectively - were assumed to represent decreasing vulnerability to fish predators. Large-sized species were also hypothesised to be more vulnerable to fish predators. The distributions of species traits were examined in relation to vegetation density. Inferring from ``predation hypothesis'' opposite selection pressures on the species traits were expected along the vegetation density. Dense macrophyte beds were thought to be dominated by invertebrate predators and open water by fish predators, since the predation efficiency of fish decreases in complex environments. In the case of invertebrate predator domination, large size and higher activity should be favoured traits among the prey species. Distribution patterns of modes of the two studied traits were explored separately for predatory and non-predatory insects. As expected, swimmers and large-sized crawlers were characteristic of the insect assemblages of dense macrophyte beds. The densities of Odonata, Corixidae, Dytiscidae, Ephemeroptera and Sialidae were higher among macrophytes than in open water, where these insect taxa were possibly depleted by fish. On the other hand, the small-sized and fairly immobile Chironomidae were the most abundant group in open water. These results support the existence of a predator transition zone among littoral vegetation, ranging from domination of invertebrate predation among the dense beds to that of fish predation in open water.[PUBLICATION ABSTRACT]
Journal Article
Effects of Natural Enemy Biodiversity on the Suppression of Arthropod Herbivores in Terrestrial Ecosystems
Claims about the role of predator diversity in maintaining ecosystem function and providing ecosystem services such as pest control are controversial, but evaluative tests are beginning to accumulate. Empirical and experimental comparisons of species-rich versus species-poor assemblages of entomophagous arthropods and vertebrates range from strong suppression to facilitative release of herbivorous arthropod prey. Top-down control can be strengthened when natural enemies complement each other, dampened by negative interactions, balanced by both factors, and driven by single influential species. A meta-analytic synthesis shows a significant overall effect of enemy richness increasing top-down control of herbivores, which is consistent in agricultural studies conducted in tropical versus temperate zones, in studies using caged versus open-field designs, but not so in nonagricultural habitats. Synthetic analyses address theory and help set precautionary policy for conserving ecological services broadly, while characterizing uncertainty associated with herbivore response to changes in enemy diversity.
Journal Article
Organic management in apple orchards: Higher impacts on biological control than on pollination
1. Intensive agricultural management negatively affects both natural enemies of pests and pollinators. Such management also has the potential to adversely affect the ecosystem services that these communities confer. Organic management has been proposed as an alternative method to mitigate such problems by restoring the services provided by arthropod communities. 2. We evaluated the effect of organic management on two ecosystem services provided by arthropods in apple orchards: pollination and biological control. We used relative decrease in colonies to assess biological control of the major apple aphid pest, and measured pollination through fruit set, number of seeds per apple and pollinator visitation. Additionally, we monitored the organisms responsible for pollination and biological control services and established the impact of pollination on apple quality. 3. Our results show a strong effect of organic management on biological control and on the temporal dynamic of natural enemy-pest interactions. Parameters such as aphid colony suppression, first and repeated occurrence of natural enemies, natural enemy species evenness and natural enemy abundance were significantly higher in organic compared to conventional orchards. Predatory bugs were the natural enemies best-affected by organic management and played a key role in early predation of aphids preventing colony growth. 4. In this instance, pollination was not influenced by organic management. It is likely due to the temporal scale at which this service is delivered, a scale that differs greatly from biological control, combined with differences in the dispersal capacity of the organisms involved. Fruit weight, calcium, potassium and magnesium content were positively affected by pollination success. 5. Synthesis and applications. We found that organic management in apple orchards preserves the local natural enemy community, and specifically predatory bug populations, essential for early aphid colony suppression. Our results suggest that, in conventional orchards, local management options that decrease or even eliminate pesticide use early in the season would increase the biological control of aphids. This would lead to reduction in apple damage at harvest. Our results on pollination success indicate that the implementation of organic management at orchard scale does not enhance pollination services for apple growers.
Journal Article
Unravelling changing interspecific interactions across environmental gradients using Markov random fields
Inferring interactions between co-occurring species is key to identify processes governing community assembly. Incorporating interspecific interactions in predictive models is common in ecology, yet most methods do not adequately account for indirect interactions (where an interaction between two species is masked by their shared interactions with a third) and assume interactions do not vary along environmental gradients. Markov random fields (MRF) overcome these limitations by estimating interspecific interactions, while controlling for indirect interactions, from multispecies occurrence data. We illustrate the utility of MRFs for ecologists interested in interspecific interactions, and demonstrate how covariates can be included (a set of models known as Conditional Random Fields, CRF) to infer how interactions vary along environmental gradients. We apply CRFs to two data sets of presence–absence data. The first illustrates how blood parasite (Haemoproteus, Plasmodium, and nematode microfilaria spp.) co-infection probabilities covary with relative abundance of their avian hosts. The second shows that co-occurrences between mosquito larvae and predatory insects vary along water temperature gradients. Other applications are discussed, including the potential to identify replacement or shifting impacts of highly connected species along climate or land-use gradients. We provide tools for building CRFs and plotting/interpreting results as an R package.
Journal Article