scholarly journals Can Generalist Predators Control Bemisia tabaci?

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 823
Author(s):  
Arash Kheirodin ◽  
Alvin M. Simmons ◽  
Jesusa C. Legaspi ◽  
Erin E. Grabarczyk ◽  
Michael D. Toews ◽  
...  
Keyword(s):  
Bemisia Tabaci ◽  
Natural Enemies ◽  
Cropping Systems ◽  
Review Literature ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Predator Species ◽  
Molecular Gut Content Analysis ◽  
Biocontrol Potential ◽  
Substantial Control

The whitefly, Bemisia tabaci, has developed resistance to many insecticides, renewing interest in the biological control of this global pest. Generalist predators might contribute to whitefly suppression if they commonly occur in infested fields and generally complement rather than interfere with specialized natural enemies. Here, we review literature from the last 20 years, across US cropping systems, which considers the impacts of generalist predators on B. tabaci. Laboratory feeding trials and molecular gut content analysis suggest that at least 30 different generalist predator species willingly and/or regularly feed on these whiteflies. Nine of these predators appear to be particularly impactful, and a higher abundance of a few of these predator species has been shown to correlate with greater B. tabaci predation in the field. Predator species often occupy complementary feeding niches, which would be expected to strengthen biocontrol, although intraguild predation is also common and might be disruptive. Overall, our review suggests that a bio-diverse community of generalist predators commonly attacks B. tabaci, with the potential to exert substantial control in the field. The key challenge will be to develop reduced-spray plans so that generalist predators, and other more specialized natural enemies, are abundant enough that their biocontrol potential is realized.

Non-pest prey do not disrupt aphid predation by a web-building spider

2015 ◽  
Vol 106 (1) ◽  
pp. 91-98 ◽  
Author(s):  
K.D. Welch ◽  
T.D. Whitney ◽  
J.D. Harwood
Keyword(s):  
Natural Enemies ◽  
Nutritional Quality ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Diversification Strategy ◽  
Molecular Gut Content Analysis ◽  
Foraging Tactics ◽  
Pest Suppression ◽  
The Cost ◽  
Web Building

AbstractA generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

scholarly journals Effects of Temporal Crop β Diversification of a Cereal-Based Cropping System on Generalist Predators and Their Biocontrol Potential

2021 ◽  
Vol 3 ◽  
Author(s):  
Giovanni Antonio Puliga ◽  
Jan Thiele ◽  
Hauke Ahnemann ◽  
Jens Dauber
Keyword(s):  
Crop Rotation ◽  
Pest Control ◽  
Cover Crops ◽  
Cropping Systems ◽  
Cropping System ◽  
Generalist Predators ◽  
Activity Density ◽  
Biocontrol Potential ◽  
Natural Pest Control ◽  
Predation Rates

In agroecosystems, crop diversification plays a fundamental role in maintaining and regenerating biodiversity and ecosystem services, such as natural pest control. Temporal diversification of cropping systems can affect the presence and activity of natural enemies by providing alternative hosts and prey, food, and refuges for overwintering. However, we still lack studies on the effects of temporal diversification on generalist predators and their biocontrol potential conducted at field scale in commercial agricultural settings. Here, we measured proxies of ecosystem functions related with biological pest control in 29 commercial agricultural fields characterized by cereal-based cropping system in Lower-Saxony, northern Germany. The fields differed in the number of crops and cover crops cultivated during the previous 12 years. Using the Rapid Ecosystem Function Assessment approach, we measured invertebrate predation, seed predation and activity density of generalist predators. We aimed at testing whether the differences in the crop rotations from the previous years would affect activity of predators and their predation rates in the current growing season. We found that the length of the crop rotation had neutral effects on the proxies measured. Furthermore, predation rates were generally lower if the rotation comprised a higher number of cover crops compared to rotation with less cover crops. The activity density of respective taxa of predatory arthropods responded differently to the number of cover crops in the crop rotation. Our results suggest that temporal crop diversity may not benefit the activity and efficiency of generalist predators when diversification strategies involve crops of very similar functional traits. Adding different resources and traits to the agroecosystems through a wider range of cultivated crops and the integration of semi-natural habitats are aspects that need to be considered when developing more diverse cropping systems aiming to provide a more efficient natural pest control.

Cursorial spiders retard initial aphid population growth at low densities in winter wheat

2008 ◽  
Vol 98 (3) ◽  
pp. 249-255 ◽  
Author(s):  
K. Birkhofer ◽  
E. Gavish-Regev ◽  
K. Endlweber ◽  
Y.D. Lubin ◽  
K. von Berg ◽  
...  
Keyword(s):  
Population Growth ◽  
Functional Groups ◽  
Arable Land ◽  
Aphid Population ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Molecular Technique ◽  
Predator Species ◽  
Web Building ◽  
The Impact

AbstractGeneralist predators contribute to pest suppression in agroecosystems. Spider communities, which form a substantial fraction of the generalist predator fauna in arable land, are characterized by two functional groups: web-building and cursorial (non-web-building) species. We investigated the relative impact of these two functional groups on a common pest (Sitobion avenae, Aphididae) in wheat by combining a molecular technique that revealed species-specific aphid consumption rates with a factorial field experiment that analyzed the impact, separately and together, of equal densities of these two spider functional groups on aphid population growth. Only cursorial spiders retarded aphid population growth in our cage experiment, but this effect was limited to the initial aphid-population growth period and low-to-intermediate aphid densities. The molecular analysis, which used aphid-specific primers to detect aphid DNA in predator species, detected the highest proportion of aphid-consuming individuals in two cursorial spiders: the foliage-dwelling Xysticus cristatus (Thomisidae) and the ground-active Pardosa palustris (Lycosidae). The results suggest that manipulating the community composition in favour of pest-consuming functional groups may be more important for improving biological control than fostering predator biodiversity per se. Agricultural management practices that specifically foster effective species or functional groups (e.g. mulching for cursorial spiders) should receive more attention in low-pesticide farming systems.

scholarly journals The influence of ecological infrastructures adjacent to crops on their carabid assemblages in intensive agroecosystems

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8094 ◽  
Author(s):  
Emilie Pecheur ◽  
Julien Piqueray ◽  
Arnaud Monty ◽  
Marc Dufrêne ◽  
Grégory Mahy
Keyword(s):  
Species Richness ◽  
Ecosystem Services ◽  
Functional Trait ◽  
Generalist Predators ◽  
Breeding Period ◽  
Generalist Predator ◽  
Weed Seed ◽  
Pitfall Trapping ◽  
Predator Species ◽  
Activity Density

Background Conserving biodiversity and enhancing ecosystem services of interest in intensive agroecosystems is a major challenge. Perennial ecological infrastructures (EIs), such as hedges and grassy strips, and annual EI under Agri-Environment Schemes appear to be good candidates to promote both. Our study focused on carabids, an indicator group responding both at the species and functional trait level to disturbances and supporting pest control and weed seed consumption services. Methods We compared carabid assemblages at the species and functional traits levels, sampled via pitfall trapping, in three types of EIs (hedges, grassy strips and annual flower strips) and crops. We also tested via GLMs the effect of (1) the type of EI at the crops’ border and (2) the distance from the crops’ border (two meters or 30 meters) on carabid assemblages of crops. Tested variables comprised: activity-density, species richness, functional dispersion metrics (FDis) and proportions of carabids by functional categories (Diet: generalist predators/specialist predators/seed-eaters; Size: small/medium/large/very large; Breeding period: spring/autumn). Results and Discussion Carabid assemblages on the Principal Coordinate Analysis split in two groups: crops and EIs. Assemblages from all sampled EIs were dominated by mobile generalist predator species from open-land, reproducing in spring. Assemblages of hedges were poor in activity-density and species richness, contrarily to grassy and annual flower strips. Differences in carabid assemblages in crops were mainly driven by the presence of hedges. The presence of hedges diminished the Community Weighted Mean size of carabids in crops, due to an increased proportion of small (<5 mm) individuals, while distance from crops’ border favoured large (between 10–15 mm) carabids. Moreover, even if they were attracted by EIs, granivorous carabid species were rare in crops. Our results underlie the importance of local heterogeneity when adapting crops’ borders to enhance carabid diversity and question the relevance of hedge implantation in intensive agrolandscapes, disconnected from any coherent ecological network. Moreover, this study emphasizes the difficulty to modify functional assemblages of crops for purposes of ecosystem services development, especially for weed seed consumption, as well as the role of distance from the crops’ border in the shaping of crop carabid assemblages.

scholarly journals Temporal variation in habitat use, co-occurrence, and risk among generalist predators and a shared prey

2016 ◽  
Vol 94 (3) ◽  
pp. 191-198 ◽  
Author(s):  
Guillaume Bastille-Rousseau ◽  
Nathaniel D. Rayl ◽  
E. Hance Ellington ◽  
James A. Schaefer ◽  
Michael J.L. Peers ◽  
...  
Keyword(s):  
Habitat Use ◽  
Rangifer Tarandus ◽  
Black Bears ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Predator Species ◽  
Prey Resources ◽  
Calving Season ◽  
Occurrence Patterns ◽  
The Relationship

Generalist predators typically have broad diets, but their diets may become constrained when one species of prey becomes disproportionately available. Yet there is poor understanding regarding whether generalist predators exhibit stereotypic relationships with pulsed prey resources. We used telemetry data from 959 woodland caribou (Rangifer tarandus caribou (Gmelin, 1788); 146 adult females, 813 calves), 61 coyotes (Canis latrans Say, 1823), and 55 black bears (Ursus americanus Pallas, 1780) to investigate how two generalist predators interacted with caribou neonates on the island of Newfoundland. We examined the similarity of patterns of habitat use between caribou and their predators across time and related this similarity to interspecific spatiotemporal co-occurrence and mortality risk for caribou neonates. The similarity in habitat use between coyotes and caribou mirrored variation in juvenile hazard risk, but had weak association with actual co-occurrence with caribou. Bears and caribou exhibited less similarity in habitat use during the calving season than coyotes and caribou. The relationship between habitat use of bear and caribou did not correspond with either co-occurrence patterns or overall risk for caribou neonates. Our work illustrates how risk for a prey species can be shaped differently based upon differences between the behavioural strategies of generalist predator species.

scholarly journals Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 321
Author(s):  
Stefan Cristian Prazaru ◽  
Giulia Zanettin ◽  
Alberto Pozzebon ◽  
Paola Tirello ◽  
Francesco Toffoletto ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Generalist Predators ◽  
Predator Species ◽  
Potted Plants ◽  
Naturally Occurring ◽  
Orius Majusculus ◽  
Limited Effectiveness ◽  
Pest Outbreaks ◽  
The Impact

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

scholarly journals Application of Trap Cropping as Companion Plants for the Management of Agricultural Pests: A Review

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 128 ◽  
Author(s):  
Shovon Chandra Sarkar ◽  
Endong Wang ◽  
Shengyong Wu ◽  
Zhongren Lei
Keyword(s):  
Pest Management ◽  
Natural Enemies ◽  
Natural Enemy ◽  
Insect Pests ◽  
Cropping Systems ◽  
Insect Pest ◽  
Critical Time ◽  
Trap Crops ◽  
Companion Plant ◽  
Trap Cropping

Companion planting is a well-known strategy to manage insect pests and support a natural enemy population through vegetative diversification. Trap cropping is one such type of special companion planting strategy that is traditionally used for insect pest management through vegetative diversification used to attract insect pests away from the main crops during a critical time period by providing them an alternative preferred choice. Trap crops not only attract the insects for feeding and oviposition, but also act as a sink for any pathogen that may be a vector. Considerable research has been conducted on different trap crops as companion plant species to develop improved pest management strategies. Despite this, little consensus exists regarding optimal trap cropping systems for diverse pest management situations. An advantage of trap cropping over an artificially released natural enemy-based biological control could be an attractive remedy for natural enemies in cropping systems. Besides, many trap crop species can conserve natural enemies. This secondary effect of attracting natural enemies may be an advantage compared to the conventional means of pest control. However, this additional consideration requires a more knowledge-intensive background to designing an effective trap cropping system. We have provided information based on different trap crops as companion plant, their functions and an updated list of trap cropping applications to attract insect pests and natural enemies that should be proven as helpful in future trap cropping endeavors.

The effects of intercropping and mixed varieties of predators and parasitoids of cassava whiteflies (Hemiptera: Aleyrodidae) in Colombia

1989 ◽  
Vol 79 (1) ◽  
pp. 115-121 ◽  
Author(s):  
Clifford S. Gold ◽  
Miguel A. Altieri ◽  
Anthony C. Bellotti
Keyword(s):  
Natural Enemies ◽  
Cropping Systems ◽  
Cropping System ◽  
Enemies Hypothesis ◽  
Natural Enemies Hypothesis ◽  
Combined Action

AbstractCassava intercropped with cowpea in Colombia had lower numbers of Aleurotrachelus socialis Bondar and Trialeurodes variabilis (Quaintance) per leaf and per plant than did monoculture cassava. These differences persisted for up to six months after harvest of the cowpea. These results are examined in light of the natural enemies hypothesis, which suggests that natural enemies may be favoured in diversified systems, thereby reducting herbivore load. In this regard, the effects of different cropping systems on the whitefly predator Delphastus pusillus (Le Conte) and on the combined action of the parasitoids Amitus aleurodinus Haldeman and Eretmocerus aleyrodiphaga (Risbec) are discussed. D. pusillus displayed a functional responce and was more abundant in monocultures than in intercrops. Predator:prey ratios were similar between treatments and so low that predation appeared to have little impact on whitefly numbers. Parasitism levels of Aleurotrachelus socialis were not affected by crop combinations. The data suggest that the activity of the natural enemies does not explain cropping system effects on cassava whitefly populations.

scholarly journals Conserving carnivorous arthropods: an example from early-season cranberry (Ericaceae) flooding

2018 ◽  
Vol 150 (2) ◽  
pp. 265-273
Author(s):  
J. van Zoeren ◽  
C. Guédot ◽  
S.A. Steffan
Keyword(s):  
Biological Control ◽  
Pest Management ◽  
Natural Enemies ◽  
Control Strategies ◽  
Cultural Control ◽  
Generalist Predators ◽  
Early Season ◽  
Insecticide Application ◽  
Insecticide Spray

AbstractBiological control plays an important role in many integrated pest management programmes, but can be disrupted by other control strategies, including chemical and cultural controls. In commercial cranberry (Vaccinium macrocarpon Aiton; Ericaceae) production, a spring flood can replace an insecticide application, providing an opportunity to study the compatibility of the flood (a cultural control) with biological control. We suspect that chemical controls will tend to reduce the number of natural enemies, while the flood, through removal of detritus and detritivores, may cause generalist predators to prey-switch to consume proportionally more pest individuals. We measured the abundance of herbivores (Lepidoptera), detritivores, Arachnida, and parasitoids (Hymenoptera) every week for six weeks in Wisconsin (United States of America) cranberry beds following either an insecticide spray or a cultural control flood. We found that detritivore populations rapidly declined in both flood and spray treatments; conversely, carnivore populations (spiders and parasitoids) were more abundant in the flooded beds than in sprayed beds. Populations of key cranberry pests were similar between flooded and sprayed beds. Our results showed that early-season flooding preserved more natural enemies than an insecticide application. This increase in natural enemy abundance after the flood may allow for greater continuity in herbivore suppression, potentially providing a basis for long-term cranberry pest management.

scholarly journals Eastern Coyotes (Canis latrans var.) consuming large ungulates in a multi-ungulate system

2020 ◽  
Vol 134 (1) ◽  
pp. 45-51
Author(s):  
Juliana Balluffi-Fry ◽  
Liane B. Nowell ◽  
Murray M. Humphries
Keyword(s):  
Prey Species ◽  
Canis Latrans ◽  
Feeding Habits ◽  
Castor Canadensis ◽  
Generalist Predators ◽  
Generalist Predator ◽  
Wide Range ◽  
Game Reserve ◽  
Varied Diet ◽  
American Beaver

The feeding habits of generalist predators often vary among populations and regions. For example, Coyote (Canis latrans), which is a generalist predator distributed across North America, occupies a wide range of habitats and has a highly varied diet. In this observational study, we quantified the presence of mammalian prey items in 50 Eastern Coyote (Canis latrans var.) scats collected in late spring and summer in a private game reserve in southwestern Quebec. Nearly all scats contained hair of White-tailed Deer (Odocoileus virginianus; 44%), Moose (Alces americanus; 38%), or American Beaver (Castor canadensis; 38%). Although all three species are known to be consumed by coyotes, such a high proportion of Moose and White-tailed Deer simultaneously occurring in the diet of coyotes has not been previously reported. The uniqueness of the study area, with its relatively high abundance of all three prey species, may account for the uniqueness of the diet of Eastern Coyotes living there.

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