-Aceria guerreronis Keifer is considered one of the main pests of coconuts around the world. Amongst the Phytoseiidae recorded on this crop, Amblyseius largoensis (Muma) has been reported in association with A. guerreronis. In order to verify whether A. largoensis feeds on A. guerreronis, the biology of this predator was evaluated on different food sources, including A. guerreronis. Three types of diet were tested [Tetranychus urticae Koch + castor bean (Ricinus communis L.) pollen + honey at 10%, A. guerreronis + pollen + honey, and only A. guerreronis], determining its development, survivorship, oviposition, sex ratio and longevity at 27ºC, 60 ± 5% RH 12 h photophase. Fertility life tables were constructed. The duration of the immature phase was lower when feeding only on A. guerreronis, while fecundity was higher when feeding on a prey + pollen + honey. There was no difference in relation to survivorship of the immature stages between the three diets. Parameters of fertility life tables were higher when the diet included A. guerreronis or T. urticae + pollen + honey, although the predator was able to complete its life cycle and reproduce when feeding exclusively on A. guerreronis. The results suggest that A. largoensis preys upon A. guerreronis under natural condition and that it might play some role in the control of the latter.KEY WORDS: Mite, biological control, Cocos nucifera RESUMO -Aceria guerreronis Keifer é considerada uma das principais pragas do coqueiro no mundo. Dentre os Phytoseiidae relatados nessa cultura, Amblyseius largoensis (Muma) tem sido encontrado associado a A. guerreronis. Com o intuito de verificar se A. largoensis se alimenta de A. guerreronis, foi estudada a biologia desse predador com diferentes fontes de alimento, incluindo A. guerreronis. Foram avaliadas três dietas [Tetranychus urticae Koch + pólen de mamona (Ricinus communis L.) + mel a 10%, A. guerreronis + pólen + mel e A. guerreronis isoladamente], avaliando-se o desenvolvimento, sobrevivência, oviposição, razão sexual e longevidade de A. largoensis a 27ºC, 60 ± 5% de umidade relativa e fotofase de 12h. Tabelas de vida de fertilidade foram construídas. A duração da fase imatura foi menor na dieta constituída apenas por A. guerreronis, enquanto que a fecundidade foi maior nas dietas à base de presa + pólen + mel. Não houve diferença entre os valores de sobrevivência das formas imaturas submetidas a diferentes dietas alimentares. Os parâmetros da tabela de vida de fertilidade foram superiores quando a alimentação foi constituída por A. guerreronis ou T. urticae + pólen + mel, embora o predador tenha sido capaz de completar seu ciclo biológico e se reproduzir quando alimentado exclusivamente com A. guerreronis. Os resultados sugerem que A. largoensis seja um predador de A. guerreronis em condições naturais e que possa estar desempenhando algum papel no controle dessa praga.
The coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), is a major pest of coconut plantations. In Brazil, the control of A. guerreronis, when accomplished, is heavily dependent on applications of conventional acaricides, which further increases the risks associated with pest resistance, hazards to human health and environmental contamination. Therefore, the development of alternatives to the chemical control concerns outlined above is urgently needed. Here, we assessed the composition, toxicity and repellent activities of cottonseed oil to A. guerreronis and its naturally occurring predator Typhlodromus ornatus Denmark & Muma (Acari: Phytoseiidae). Our results revealed that the major compounds in cottonseed oil were linoleic and oleic acids, which have been shown to be bioactive against pests. Concentration-mortality bioassays revealed that A. guerreronis (LC50 = 0.65 μL/cm2) was more susceptible to cottonseed oil than its predator (LC50 = 5.11 μL/cm2). Similarly, as demonstrated for the conventional acaricides (i.e., abamectin, azadirachtin, espirodiclofen, and fenpyroximate), cottonseed oil was shown to repel A. guerreronis and its predator. Overall, our findings support the use of cottonseed oil as a desirable tool to be integrated in management programs aimed at controlling A. guerreronis.
-Aceria guerreronis Keifer is an important pest of coconut worldwide. Due to the lack of standardized methods to quantify damage of this eryophyid, a diagrammatic scale with indices of 1, 2, 4, 8, 16, 32, 48 and 70% of damage caused by A. guerreronis was elaborated and tested to accuracy, precision and reproduction of the estimations. To validate the scale, fruits with different levels of damage were previously measured with the program Assess and submitted to 10 inexperienced evaluators with or without the scale (1ª evaluation) and seven days after (2ª evaluation) with the same evaluators, using digitized pictures of the same fruits in a different sequence. The accuracy and precision of each evaluator was determined through linear regression between observed and estimated damage. Without using the scale, evaluators were less precise as seven out of 10 overestimated the damage, while evaluators provided with the scale were much more accurate. Also, evaluations with the aid of the scale were much more reproducible than without the scale. The scale was used to determine the relationship between infestation and damage levels caused by A. guerrerronis. The relationship between infestation and damage fi tted by the equation lny = 4.948 -0.121x + 1.789 lnx (R 2 = 99.87%, P < 0.0001). Therefore, these fi ndings show that it is possible to estimate A. guerreronis population density on infested coconut fruits by using the diagrammatic scale.KEY WORDS: Cocos nucifera, coconut mite, eriophyid, scale of damage, damage evaluation, damage estimation RESUMO -Aceria guerreronis Keifer é importante praga do coqueiro no mundo. Dada a falta de métodos padronizados para a quantifi cação dos danos causados por esse eriofi ídeo, uma escala diagramática com níveis de 1, 2, 4, 8, 16, 32, 48 e 70% de danos foi elaborada e testada para precisão e reprodutibilidade das estimativas. Para validar a escala, frutos com diferentes níveis de dano foram previamente avaliados com o programa Assess e submetidos à avaliação por 10 avaliadores inexperientes com e sem a escala (1ª avaliação) e sete dias após (2ª avaliação) com os mesmos avaliadores, empregandose as fotos digitalizadas dos mesmos frutos com seqüência diferente. A acurácia e a precisão de cada avaliador foram determinadas por regressão linear simples entre o dano observado e estimado. Sem a utilização da escala, sete de 10 avaliadores superestimaram o nível de dano, sendo pouco precisos. No entanto, avaliadores utilizando a escala obtiveram melhores níveis de acurácia e precisão. Os avaliadores apresentaram níveis mais elevados de reprodutibilidade das estimativas com a utilização da escala comparada às avaliações sem a escala. A escala foi utilizada para determinar a relação entre a infestação e o dano causado por A. guerreronis. A relação entre infestação e níveis de dano apresentou elevada precisão (R 2 = 99,87%, P < 0,0001) pela equação lny = 4,948 -0,121 x + 1,789 lnx. Portanto, os resultados comprovam que é possível estimar a população de A. guerreronis nos frutos de co...
The dispersal of plant-feeding mites can occur involuntarily, through transportation of infested plant parts, or voluntarily, by walking to new plant parts or to suitable spots where biotic (phoresis) or abiotic (wind, agricultural tools, etc.) factors carry them over long distances. Elucidating the dispersal mechanisms of the coconut mite, Aceria guerreronis Keifer, is important for understanding the process of colonization of new fruits of a same or different plants, essential for the improvement of control strategies of this serious coconut pest. Thus, the objective of this work was to investigate the voluntary dispersal mechanisms of this mite. The hypothesis that the coconut mite disperses by walking, phoresis or wind were tested. The coconut mite was shown to be able to walk short distances between fruits of the same bunch or between bunches of the same plant. Phoresis on insects of the orders Hymenoptera (Apidae), Coleoptera (Curculionidae) and Lepidoptera (Phycitidae) was evaluated in the laboratory and in the field. Although in the laboratory mites were shown to be able to climb onto honeybees, field investigations failed to show these insects as important carriers of the pest, corroborating findings of previous works; however, both laboratory and field investigations suggested the curculionid Parisoschoenus obesulus Casey to be able to transport the coconut mite between plants. Similarly, laboratory and field investigations suggested wind to be important in the dispersal of the coconut mite between plants.
The coconut mite, Aceria guerreronis (Acari: Eriophyidae), is a major tropical pest of coconut. Here, we assessed the chemical profiles and the potential use of babassu, degummed soybean, and coconut oils to control A. guerreronis as well as their side-effects on the predatory mite Neoseiulus baraki (Acari: Phytoseiidae), a key natural enemy of the coconut mite. Babassu and coconut oils had similar fatty acids chemical profiles. All vegetable oils showed toxicity to A. guerreronis; degummed soybean oil exhibited the highest toxicity (LC = 0.15 µL/cm). Although all oils were less toxic to N. baraki, their potential to attract/repel this predatory mite differed. Whereas N. baraki females were unresponsive to coconut oil at both concentrations (i.e., LC and LC estimated for A. guerreronis), irrespective of exposure period (i.e., 1 or 24 h), the babassu oil repelled the predator, independent of exposure period, when applied at its LC (1.48 µL/cm). Intriguingly, this oil also exhibited attractiveness to N. baraki 24 h after exposure when applied at its LC (0.26 µL/cm). A similar attractiveness pattern was recorded 24 h after N. baraki was exposed to degummed soybean oil at both concentrations tested (LC = 0.15 µL/cm; LC = 1.39 µL/cm). However, N. baraki was repelled by degummed soybean oil at its LC after 1 h of exposure. Therefore, the present study demonstrated that all the vegetable oils used here had higher toxicity to the coconut mite and considerable selectivity to the predator N. baraki, indicating they are promising tools that can potentially be included in management programs to control A. guerreronis in commercial coconut plantations.
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