The lacewing Ceraeochrysa caligata as a potential biological agent for controlling the red palm mite Raoiella indica.

BACKGROUND: Compared to chemical control, the use of naturally occurring biological agents to control invasive pests is less threatening to the environment and human health. OBJECTIVES: Here, we assessed the ability of immature stages of the lacewing Ceraeochrysa caligata (Neuroptera: Chrysopidae) to prey upon different developmental stages of the red palm mite Raoiella indica (Acari: Tenuipalpidae), one of the most destructive invasive pests of palm trees in Neotropical regions. METHODS: Increasing densities of three stages of R. indica (eggs, immature stages, and adult females) were offered to C. caligata in coconut leaf arenas. The immature stages of C. caligata were less than 24 h old and were starved before being transferring to the arenas. The amount of prey consumed was recorded 6 h after releasing the C. caligata. RESULTS: Our results indicated that the ability of C. caligata to feed upon R. indica increased with the larval development of the predator. Higher feeding levels and shorter handling times were recorded for the first and second instars of C. caligata when preying upon the eggs and immature stages of R. indica. Furthermore, C. caligata individuals of different stages exhibited differential functional responses according to prey type (i.e., eggs, immatures, or adult females of R. indica). Ceraeochrysa caligata second instar individuals exhibited a sigmoid increase in consumption rate with increasing prey availability (i.e., a type III functional response) when preying upon immature stages of R. indica. However, when preying upon R. indica adult females, C. caligata second instar individuals exhibited a type II functional response (i.e., an increase in consumption rate with increasing prey availability, before reaching a plateau). Predator individuals of the first and third instar stages exhibited a type II functional response for all prey types. CONCLUSIONS: Collectively, our findings demonstrate that C. caligata, especially at the second instar stage, has potential as a tool for ecological management of the red palm mite.

Toxicity of vegetable oils to the coconut mite Aceria guerreronis and selectivity against the predator Neoseiulus baraki.

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 (LC50 = 0.15 µL/cm2). 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., LC50 and LC99 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 LC99 (1.48 µL/cm2). Intriguingly, this oil also exhibited attractiveness to N. baraki 24 h after exposure when applied at its LC50 (0.26 µL/cm2). A similar attractiveness pattern was recorded 24 h after N. baraki was exposed to degummed soybean oil at both concentrations tested (LC50 = 0.15 µL/cm2; LC99 = 1.39 µL/cm2). However, N. baraki was repelled by degummed soybean oil at its LC50 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.

Dispersal strategies of Aceria guerreronis (Acari: Eriophyidae), a coconut pest.

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.

Distribution of Aceria guerreronis and Neoseiulus baraki among and within coconut bunches in northeast Brazil.

Aceria guerreronis Keifer (Acari: Eriophyidae) is considered a major pest of coconut in many countries in the Americas, Africa and parts of Asia. Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) is one of the predatory mites most commonly found in association with A. guerreronis in parts of northeast Brazil. The objective of this work was to study the distribution of A. guerreronis and N. baraki among and within coconut bunches. The hypothesis was tested that A. guerreronis and N. baraki are homogenously distributed over the fruits in a bunch, independent of the fruits' age and position. Five collections of bunches, each corresponding to leaves 12-16 from apex (about 2-6 month-old), were conducted in each of three fields in northeastern Brazil, from February to October, 2007. A total of 1,986 fruits were examined. The number of mites, the percentage of fruits hosting them and the level of damage caused by A. guerreronis were evaluated. The highest density of A. guerreronis was observed on fruits of bunch 4 whereas the highest density of N. baraki was observed on bunch 5. Considering all fruits together, no significant differences were observed between densities of either A. guerreronis or N. baraki among the basal, median and apical thirds of the bunches. In younger bunches, fruits of the apical region tend to have lower densities of both mites than fruits of the basal region. This pattern, in association with a similar pattern for the percentage of fruits hosting N. baraki, suggests that the predator initially reaches the basal bunch region, from where it moves to the apical region. The results of the present study suggest that the pest population reduction in bunches older than bunch 4 could be due to (1) an effect of the predator, (2) reduction of the proportion of undamaged tissues amenable to attack, and/or (3) less favorable characteristics of the fruits to attack by A. guerreronis, as indicated by their increasing lignin content as they get older.

Life history of Proctolaelaps bulbosus feeding on the coconut mite Aceria guerreronis and other possible food types occurring on coconut fruits.

Aceria guerreronis Keifer (Acari: Eriophyidae) is a major pest of coconut fruits (Cocos nucifera L.) in many countries of the Americas, Africa, and parts of Asia. Considerable attention has been given to studies of biological control agents of A. guerreronis. Proctolaelaps bulbosus Moraes, Reis and Gondim Jr. is a predator recently discovered in association with A. guerreronis. Nothing is known about its biology. The aim of this study was to determine suitable food sources for P. bulbosus, among items commonly found on coconut fruits, including A. guerreronis. Food sources evaluated included the mites A. guerreronis, Steneotarsonemus concavuscutum Lofego and Gondim Jr., and Tyrophagus putrescentiae (Schrank), the fungus Rhizopus aff. stolonifer (Ehrenb.) Vuill and coconut pollen; the mite Tetranychus urticae Koch was also included in the assessments, for being a commonly used prey for mass production and laboratory rearing of predatory mites. Proctolaelaps bulbosus was able to develop up to adulthood when fed A. guerreronis, R. aff. stolonifer and T. putrescentiae. It had the highest population growth rates when feeding on the former (R (o) = 17.5; r (m) = 0.392). These results indicate that A. guerreronis is the most suitable food for P. bulbosus among the possible food sources found on coconut fruits and that P. bulbosus can survive in the absence of eriophyid using R. aff. stolonifer as a food source.

Escala diagramática de dano de Aceria guerreronis Keifer (Acari: Eriophyidae) em coqueiro / Diagrammatic scale of Aceria guerreronis Keifer (Acari: Eriophyidae) damage in coconut

Aceria guerreronis Keifer é importante praga do coqueiro no mundo. Dada a falta de métodos padronizados para a quantificação dos danos causados por esse eriofiídeo, 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. Osavaliadores 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 (R2 = 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 coco infestados com a utilização da escala diagramática.

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 relationshipbetween infestation and damage fi tted by the equation lny = 4.948 - 0.121x + 1.789 lnx (R2 = 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.

[Diagrammatic scale of Aceria guerreronis Keifer (Acari: Eriophyidae) damage in coconut]. / Escala diagramática de dano de Aceria guerreronis Keifer (Acari: Eriophyidae) em coqueiro.

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(R) and submitted to 10 inexperienced evaluators with or without the scale (1 feminine evaluation) and seven days after (2 feminine 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 fitted by the equation lny = 4.948 - 0.121x + 1.789 lnx (R(2) = 99.87%, P < 0.0001). Therefore, these findings show that it is possible to estimate A. guerreronis population density on infested coconut fruits by using the diagrammatic scale.

[Biology of Amblyseius largoensis (Muma) (Acari: Phytoseiidae), a potential predator of Aceria guerreronis Keifer (Acari: Eriophyidae) on coconut trees]. / Biologia de Amblyseius largoensis (Muma) (Acari: Phytoseiidae), um potencial predador de Aceria guerreronis Keifer (Acari: Eriophyidae) em coqueiro.

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 27 degrees C, 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.

Biologia de Amblyseius largoensis (Muma) (Acari: Phytoseiidae), um potencial predador de Aceria guerreronis Keifer (Acari: Eriophyidae) em coqueiro / Biology of Amblyseius largoensis (Muma) (Acari: Phytoseiidae), a potential predator of Aceria guerreronis Keifer (Acari: Eriophyidae) on coconut trees

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 por cento, A. guerreronis + pólen + mel e A. guerreronis isoladamente], avaliando-se o desenvolvimento, sobrevivência, oviposição, razão sexual e longevidade de A. largoensis a 27°C, 60 ± 5 por cento 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.

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 percent, A. guerreronis + pollen + honey, and only A. guerreronis], determining its development, survivorship, oviposition, sex ratio and longevity at 27°C, 60 ± 5 percent 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.