Functional and numerical responses of the predatory mite Amblyseius aerialis (Acari: Phytoseiidae) to Aceria guerreronis (Acari: Eriophyidae)

The coconut mite, Aceria guerreronis Keifer, is one of the main pests of the coconut tree (Cocos nucifera L.) worldwide. Its control is mainly based on the use of acaricides. However, due to the habitat of this pest mite, which is protected by fruit bracts that act as a physical barrier, chemical control is often inefficient. Thus, natural enemies have been studied as an alternative to acaricides. We evaluated the functional and numerical responses of Amblyseius aerialis (Muma) to increasing densities of A. guerreronis (40, 80, 160, 240 and 360) and additionally the oviposition rates of the phytoseiid A. aerialis over 11 days on different food sources: coconut pollen, A. guerreronis and a mix of pollen and A. guerreronis. Our results showed that Amblyseius aerialis showed a type III functional response, where prey consumption increasing as the density of A. guerreronis increased, with a maximum consumption of up to 175 prey per predator. All the prey densities allowed female oviposition. The number of eggs laid by A. aerialis increased with increasing prey density and stabilized between 240 and 360 A. guerreronis individuals, with an average oviposition of 1.7 eggs/female. Furthermore, our results showed that all the food sources (coconut pollen, A. guerreronis and a mix of pollen and A. guerreronis) supported oviposition. The mean oviposition was approximately 1.5 eggs/female on all the food sources. Our study suggests that A. aerialis can be effective in the biological control of A. guerreronis. However, further studies are needed to investigate whether A. aerialis can explore the habitat of A. guerreronis and if that prey can support the development of immature stages and the reproduction of A. aerialis.

Composition and Bioactivity of Essential Oil From the Leaves of Genipa americana Against the Coconut Mite Aceria guerreronis

Genipa americana L. has a diversity of secondary metabolites, including iridoids, phenolic compounds, and alkaloids. Pharmacological and biological properties have also been reported. This study has aimed to evaluate the chemical composition of the essential oil (EO) obtained from the leaves of G. americana and its bioactivity against Aceria guerreronis Keifer (Acari: Eriophyidae), a serious pest of coconut production areas worldwide. EO from the leaves was extracted and analyzed by Gas Chromatography-Mass Spectrometry and flame ionization detection (GC-MS/FID). For the bioassays, the adult coconut mites were subjected to increasing concentrations of EO. The analyses showed a predominance of sesquiterpenes, followed by monoterpenes, aldehydes, and fatty acids. The EO (LC50 = 0.41 mg mL-1; LC90 = 6.43 mg mL-1) showed toxicity and repellent effects against the coconut mite. The tested EO has the potential to develop as a natural product, with acaricidal activities against A. guerreronis, in order to assist in the control of the coconut mite.

Adoption of Recommended Plant Protection Measures for the Management of Major Coconut Pests by Coconut Growers in Kurunegala District, Sri Lanka

Coconut production in Sri Lanka is threatened by pest and diseases. Therefore, different remedial measures have been introduced by Coconut Research Institute (CRI) to safeguard the plantations. This study was carried out to determine the adoption of recommended plant protection measures to manage major pests of coconut by the growers in different land categories. The growers were selected from Kurunegala district, which is the major coconut growing district in coconut triangle in Sri Lanka. Findings of the study revealed that more than 70 percent of the growers in all land categories above 2Ac had adopted technologies recommended by CRI to control black beetle. Technology adoption was around 60 percent for red weevil control, around 30 percent for coconut mite and around 65 percent for plesispa beetle. It was also noted that the decision making on the adoption of different technologies is affected by the perceptions of the growers. Growers’ perception was determined by two factors, information receiving sources and occurrence of pest attacks in their fields. Further, it was found that the growers are having limited access to latest technologies in pest control. In addition, the study revealed that unawareness of technologies and low attention for coconut farming was the two major reasons for poor adoption of the recommended technologies. It is concluded that coconut growers in Kurunegala district require more awareness regarding recommended plant protection measures to manage major coconut pests and strengthen extension programes.

Perceptions of Farming Community in Relation to Problems in Farming and Prospects of Coconut Mite Management in Bangladesh

A study was conducted to analyze community perception on homestead agro-biodiversity and conservation of coconut genetic resources at Bagharpara Upazila (Sub district) of Jashore district, Bangladesh in October 2011. Tools and techniques of Participatory Rural Appraisals (PRA) were utilized to identify the socio-economic factors and agronomic practices influencing homestead agro-biodiversity. The participants identified coconut as a leading species in the homesteads. Communities suspected that the wave (electro-magnetic) generating from mobile phone towers was the cause of damaging coconut in their villages. Being disheartened with continuous yield loss, the farmers have resorted to fell down their coconut trees and shifted to cultivating fruit trees or suitable field crops. The research team used the matrices of PRA to develop a problem tree, which marked mite infestation in coconut as the focal problem. The developed problem-tree was transposed into an objective tree. Based on the objective tree, the research team was able to develop and implement a three-year research project on mite management in coconut involving farmers as implementers. The intervention stimulated community knowledge and skills towards mite management and conservation of unique traditional coconut varieties.

Acute and non-lethal effects of coconut oil on predatory mite Typhlodromus ornatus (Acari: Phytoseiidae)

Typhlodromus (Anthoseius) ornatus Denmark & Muma (Acari: Phytoseiidae) is one of the predatory mites associated with the coconut mite Aceria guerreronis (Acari: Eriophyidae), a serious coconut pest in Africa, Asia and America. Vegetable oils such as coconut oil have been shown to efficiently control A. guerreronis, however their side effects on predatory mites remain poorly investigated. Here, we evaluated the lethal and non-lethal effects of coconut oil on repellence and functional response of the predatory mite T. ornatus, a natural enemy of A. guerreronis. Based on LC50 estimates, coconut oil was over 6-fold less toxic to T. ornatusthan to its prey, A. guerreronis. Additional repellence and predation bioassays show that the coconut oil neither repels nor interferes in the functional response of T. ornatus preying upon A. guerreronis. According to our selectivity approach, the coconut oil is compatible with the predatory mite T. ornatus.

Management of Coconut Mite in Bangladesh Involving Communities as Implanter

A study on management of coconut mite (Aceria guerreronis Keifer, Acari: Eriophyidae) was carried out in farmers fields at Bagharpara Sub-district of Jashore district, in an area of about 696 ha during May 2011 to June 2014. The mite attacking coconut in Bangladesh remained unidentified until 2008. Field and laboratory studies on morpho-anatomy revealed that 2-6 month old nuts hosted colonies of mites while no mites were found on unfertilized button (flowers) and nuts of more than 06 months old. Colonization was found maximum in younger nuts of 3 -4 month old. Mites were found to reside under the perianth near the stalk of young coconut. Six different treatments viz, removing of infested young nuts and foliar application of Omite @ 0.2% adjacent to the bunch region (T1); removing of infected young nuts and foliar application of Neem-oil @ 0.3% adjacent to the bunch region (T2); T1 & soil incorporation of Neem cake @ 500g/tree (T3); T1 & soil incorporation of tricho-compost @ 2000g/tree (T4); T2 & soil incorporation of Neem cake @ 500g/tree (T5) and T2 & incorporation of tricho-compost 2000g/tree (T6). Results of three consecutive years showed that all the treatments were equally effective in controlling mite attack in coconut. Edible portion of mature nuts was found to improve by the treatments T3 and T5, containing soil incorporated Neem cake. Days to spath opening, male phase, number of bunch and nut per bunch were not influenced by any one of the treatments. On an average 77 nuts were harvested/palm/year and their estimated market value was Taka 1540. Income augmented due to technology was Taka 1339.80 with BCR value 6.

Bioactivity of cottonseed oil against the coconut mite Aceria guerreronis (Acari: Eriophyidae) and side effects on Typhlodromus ornatus (Acari: Phytoseiidae)

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.