•A ten-fold higher abundance of T. urticae was found in conventional strawberry sites than in organic sites.•The ratio of spider mites to predatory mite was 9.5 times lower in organic sites.•Natural ...enemy abundance was higher in the surrounding vegetation than in the crop.•Species richness was highest in the edges of organic fields and surrounding vegetation.
Cropping practice influence arthropod species abundance and diversity in agroecosystems, thus impacting populations of insect pests and their natural enemies. A field study was conducted to investigate whether pest and natural enemy abundance was higher in organic compared with conventional strawberry fields, and whether the non-managed vegetation surrounding the field impacted natural enemy abundance and diversity in and around the field sites. The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), and predatory mites were sampled from strawberry leaflets and the leaves of wild herbaceous plants from the surrounding vegetation. Insect predators, hymenopteran parasitoids, spiders and herbivores were collected from the same habitats. Abundance of T. urticae was ten-fold higher in conventional compared to organic strawberry fields, whereas the ratio of spider mite to predatory mites was 9.5 times lower in organic compared with conventional strawberry fields. The 14 species of predatory mites identified were all from the family Phytoseiidae, and predominantly found on stinging nettle, Urtica dioica L. (Rosales: Urticaceae) (> 80% of individuals), in the surrounding vegetation. There was no significant effect of cropping practice on the density of insect predators and spiders, while the density of insect parasitoids and insect herbivores was higher in the organic compared to the conventional sites. Total species richness at the edge of organic fields and in the surrounding vegetation of both organic and conventional sites was higher than in the other sampling sites. This study demonstrates the major impact of cropping practice on T. urticae abundance and on the prey to predator ratio, whilst also emphasizing the importance of the surrounding vegetation as a source of natural enemies of phytophagous arthropods.
Phytoseiid mites are commonly used as biological control agents of mite and small insect pests. To facilitate the production of phytoseiids, alternative food sources have been evaluated. The aim of ...this study was to evaluate the suitability of different food sources for the rearing of the phytoseiids
Amblyseius tamatavensis
Blommers,
Euseius concordis
(Chant) and
Neoseiulus anonymus
(Chant and Baker). This study evaluated the levels of oviposition of these predators when fed with 15 Astigmatina (Sarcoptiformes) mite species, one species of a bacteriophagous nematode, and pollen from five plant species. The highest oviposition rates of
A. tamatavensis
were obtained when fed on the mites
Thyreophagus cracentiseta
Barbosa, OConnor & Moraes and
Aleuroglyphus ovatus
(Troupeau) (2.6 and 2.1 eggs/female/day, respectively). The five highest oviposition levels of
E. concordis
occurred when the food source was pollen, especially of
Ricinus communis
L. (1.7 eggs/female/day). The evaluated oviposition levels of
N. anonymus
were at most 0.5 eggs/female/day on all food sources. The construction of life tables of
A. tamatavensis
and
E. concordis
with the two most favorable food sources showed that in both cases the values of r
m
were higher when the predator was fed with
T. cracentiseta
and
R. communis
, respectively. The possible use of pollen of
Elaeis guineensis
L. should be further evaluated, given the acceptance of this type of pollen by
E. concordis
and the ease of obtaining large amounts of this pollen in areas where this crop is grown.
•Amblyseius tamatavensis is a promising predator for the control of Bemisia tabaci.•Functional response of A. tamatavensis to B. tabaci eggs on five plants was evaluated.•Predation was higher on ...potato and cotton and lower on tomato and melon.•Amblyseius tamatavensis had type II functional response on all plants.•Attack rate and handling time were not influenced by plant species.
Amblyseius tamatavensis Blommers is a promising predator for the control of the whitefly Bemisia tabaci (Gennadius), a polyphagous pest. Since the architecture of the host plant may affect prey consumption by predatory mites, this work evaluated the consumption of eggs of B. tabaci by A. tamatavensis on different plants (cotton, bean, potato, melon and tomato). Functional responses were determined by logistic regression of eggs consumed as a function of initial number of prey using a polynomial logistic regression; the random predator equation was used to describe functional response parameters. Predation was higher on cotton and potato leaves, whereas the lowest prey consumption was obtained on tomato and melon. Amblyseius tamatavensis had functional response of type II on all plants and attack rate and handling time were not influenced by plant species. The results obtained confirm that A. tamatavensis is a promising predator of B. tabaci, but its efficacy may vary with leaf surface texture, especially trichome density.
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•Thrips eggs imbedded in leaf tissue are vulnerable to attack by certain phytoseiids.•The generalists Amblyseius largoensis and A. swirskii most readily fed on thrips eggs.•Egg ...predation should be considered when evaluating phytoseiids for thrips control.
It is generally assumed that predation by phytoseiid mites (Acarina: Phytoseiidae) on thrips is mainly limited to the first and, to a lesser extent, the second thrips instars. Thrips eggs are imbedded in plant tissue and are supposed to be out of reach of most predators. Using a dual approach combining feeding trials with molecular gut content analysis, we confirmed that eggs of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), can be vulnerable to attack by a subset of phytoseiid species. Of the five species investigated, the generalist predators Amblyseius largoensis and Amblyseius swirskii were shown to most readily feed on thrips eggs, followed by Neoseiulus californicus, which is classified as a selective predator of tetranychid mites. Neoseiulus longispinosus and Proprioseiopsis lenis did not or very rarely consume thrips eggs. As substantial reductions of hatching (up to 30%) were observed, predation on eggs should not be ignored when assessing the efficacy of phytoseiids as biological control agents against thrips.
Raoiella indica Hirst (Acari: Tenuipalpidae), a pest of coconut and other species of palms, recently invaded the Western Hemisphere. Amblyseius largoensis (Muma) (Acari: Phytoseiidae), is a predatory ...mite found associated with R. indica in different parts of the world. Exclusion and release tactics were used to obtain coconut palms with varying levels of A. largoensis in order to quantify their effects on R. indica densities. Four treatments consisting of 4 rates of release of A. largoensis females (0 = control, 1:10, 1:20 and 1:30 A. largoensis: R. indica) were tested. The releases of A. largoensis resulted in a significant reduction of R. indica densities and less damaged leaf area in the treated coconut palms compared to the controls within 3 months. The largest pest density reduction ( similar to 92%) was observed at the highest predator release rate (1:10 A. largoensis: R. indica). The other 2 release rates (1:20 and 1:30 A. largoensis: R. indica) caused significant and equivalent reductions in pest densities (55 and 43%, respectively). Results of this study support the hypothesis that A. largoensis is an important mortality factor of R. indica and should be considered as a key biological control agent in IPM programs targeting R. indica.
Debido al uso irracional de productos químicos para el control de plagas en los cultivos intensivos, se han disminuido de manera alarmante la diversidad de comunidades de organismos benéficos, tal es ...el caso de los ácaros depredadores del orden Mesostigmata. Estos arácnidos han tomado relevancia agrícola debido a que, la mayoría de sus miembros presentan hábitos alimentarios zoofágicos y regulan de manera natural poblaciones perjudiciales de insectos, nematodos y otros ácaros que habitan las plantas. De manera regular, desde hace más de 40 años se introducen los ácaros depredadores para los trabajos de biocontrol y se estima que más de 60% de los programas utilizan estos organismos; sin embargo, los productos comerciales disponibles están limitados a unas pocas especies, las cuales varían en efectividad según las condiciones del cultivo, disponibilidad de presas y competencia de nichos con otros organismos también depredadores, además, su producción está resguardada bajo secreto empresarial en la mayoría de los casos. Con esto, se abre la oportunidad para explorar especies nativas o incluso ya comercializadas, con el fin de evaluar su capacidad depredadora a nivel de investigación o como herramientas habituales para la regulación de plagas, un primer reto para este fin es la propagación y los métodos de cultivo. Los métodos para cultivar ácaros se pueden dividir en dos: mantenimiento sobre plantas y en confinamiento, aunque cada técnica se ha desarrollado para una especie en particular o un fin determinado, el conocer su diseño básico, promete acercarnos a una nueva línea de estudio para su introducción y reintroducción en los sistemas agrícolas.
•Natural enemies can regulate populations of Brevipalpus yothersi.•Phytoseiid and cheyletid predators were evaluated for control of Brevipalpus yothersi.•Amblyseius largoensis suppressed Brevipalpus ...yothersi on citrus plants.•Predatory mites can be important in IPM programs tailored to manage citrus leprosis.
Citrus leprosis is a serious viral disease of citrus transmitted by Brevipalpus mites. The disease is present in South America, Central America, and Mexico, but not in the United States. One of its primary vectors, however, is present in Florida and other southern states. Non-viruliferous Brevipalpus yothersi (Acari: Tenuipalpidae) are present in Florida and could facilitate the spread of the disease if citrus leprosis viruses (CiLVs) are introduced into the state. In preparation for the possible incursion of CiLVs, we evaluated the biological control potential of four predatory mite species (Neoseiulus longispinosus, N. californicus, Amblyseius largoensis; Acari: Phytoseiidae) and Hemicheyletia bakeri (Acari: Cheyletidae) that are naturally associated with Brevipalpus spp. in citrus. In laboratory no-choice assays, the phytoseiid mites preyed mostly upon immature stages of B. yothersi, while H. bakeri preyed mainly on adults. In dual choice assays, all predators preferred Tetranychus urticae (Acari: Tetranychidae) over B. yothersi, but A. largoensis consumed more B. yothersi than the other three predators. A greenhouse experiment was performed to evaluate the potential of A. largoensis and H. bakeri to suppress B. yothersi populations on citrus trees. Four predator release treatments consisting of single or combined releases of A. largoensis and H. bakeri at a 1:10 (predator: B. yothersi) ratio were tested. Releases of A. largoensis alone or in combination with H. bakeri effectively suppressed B. yothersi and reduced damage to citrus plants. Release of H. bakeri alone, however, had no suppressive effect on B. yothersi populations. Overall, our results show that A. largoensis could be an efficient biological control agent of B. yothersi and could play an important role in citrus IPM programs tailored to manage citrus leprosis.
Mitochondrial (mt) gene sequences have been widely used to infer phylogeny in animals. The relative order of mt genes in the mitogenome can also be a useful marker for evolution, but the propensity ...of mt gene rearrangements vary tremendously among taxa. Ticks and mites in Acari exemplify this trend as some families retain the ancestral arthropod gene order, while others show highly divergent gene orders. Mites in Phytoseiidae, many of which are effective biological control agents, show some of the most divergent gene orders. However, the diversity of mitogenome order within this family is little known. We thus sequenced three mt genomes of phytoseiid mites from two of the most speciose genera: Amblyseius swirskii (Athias-Henriot), Amblyseius tsugawai (Ehara) and Neoseiulus womersleyi (Schicha). We find differences in mt GC skew and nucleotide composition, especially between N. womersleyi and the two Amblyseius species. Each species within Phytoseiidae (including three previously available sequences) present a unique gene order. Phytoseiid mitogenomes show some of the highest numbers of breakpoints when compared to the ancestral arthropod order (up to 33), as well as high numbers of breakpoints within the family (14-30). This suggests a history of massive, ongoing mitogenome rearrangements in the family. Phylogenetic analyses of mt sequences confirm that the degree of gene rearrangements follows phylogenetic relatedness. We discuss possible causes for the high degree of mt gene rearrangement within phytoseiid mites as well as selection in the mt and nuclear genome tied to the independent evolution of many diverse feeding strategies in the family. Finally, we suggest N. womersleyi should be used instead of the synonym Amblyseius pseudolongispinosus.
•Each phytoseiid mitogenome shows a unique mt gene order.•Phytoseiids have highest number of mt breakpoints in Mesostigmata.•Phylogenetic analyses of mt genes supports gene order as a marker of relatedness.•Diverse feeding strategies have likely evolved independently in phytoseiids.•Characteristics of mt genome facilitates taxonomy of Neoseiulus and Amblyseius.
Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an economically important biocontrol agent, was reared on almond pollen for 50 generations. We evaluated the effect of rearing predators on this ...pollen by comparing biological parameters at different generations (G1–G50). The shortest and longest development time occurred in G5 and G10, respectively. Females at the fifth and 50th generations laid eggs earlier than those of other generations. Females at G50 laid eggs over a longer period and produced more eggs than females of other generations, although females in the earlier generations had a higher gross reproductive rate and net reproductive rate than later generations. The intrinsic rate of increase, as well as the finite rate of increase of N. cucumeris in the fifth and 50th generations was significantly greater than those in other generations, while the first generation had the lowest values of these parameters. The dorsal shield length of both females and males and the width of females were found to be unaffected by their constant feeding on almond pollen. However, the number of rearing generations significantly affected the width of males. Long-term rearing of N. cucumeris for at least 50 generation on almond pollen did not substantially affect the predator's quality and this food source could be used for the mass production of this predator. Almond pollen should be assessed in rearing other phytoseiid mites that are important in biocontrol strategies.
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