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.
O açaizeiro (Euterpe oleraceae) é a mais importante palmeira do gênero Euterpe conhecida no Brasil, que é cultivada em sistemas de cultivo solteiro e consorciado. Apesar da grande utilidade, esta palmeira se destaca no fornecimento de dois produtos alimentares economicamente rentáveis, os frutos e o palmito. Em razão da sua importância, objetivou-se com este trabalho realizar o levantamento da acarofauna presente em cultivos de açaizeiro no município de São Luís - Maranhão. As amostragens foram realizadas mensalmente, no período de agosto de 2012 a julho de 2013, em açaizeiros cultivados em dois sistemas plantio: solteiro e consorciado. A análise faunística foi feita pelo programa ANAFAU, no qual foram determinados os índices de abundância, frequência, dominância, constância e diversidade. Foram encontrados 6.274 ácaros, sendo 4.748 no sistema de consórcio e 1.526 no cultivo solteiro. Entre a ocorrência de ácaros fitófagos, as famílias Tenuipalpidae e Tetranychidae se destacaram nos dois cultivos. Em relação às famílias de ácaros predadores, a Phytoseiidae foi considerada superdominante, superabundante, superfrequente e constante; as espécies Amblyseius largoensis, Euseius concordis e Iphiseiodes zuluagai foram dominantes em ambos os sistemas de cultivo, porém o cultivo consorciado apresentou maior diversidade em relação ao cultivo solteiro. Na flutuação populacional, observaram-se maiores populações de ácaros nos períodos de menor precipitação pluviométrica nos dois sistemas estudados.
Citrus black fly Aleurocanthus woglumi Asbhy is an important citrus pest because it causes significant losses in production. The objective of this study was to evaluate the incidence and distribution of A. woglumi egg laying, eggs and nymphs on Citrus latifolia (Tahiti acid lime) plants grown under different fertilizer applications. The experiment was carried out in a citrus orchard in the municipality of Paço do Lumiar, MA, Brazil. A randomized block design in a 3×5×3 factorial arrangement (three evaluation times, five treatments, and three plant strata) was used with 4 replications. The experimental unit consisted of three plants and treatments with different fertilizations were applied to the soil: T1: control (no fertilizer application); T2: organic fertilizer (bovine manure); T3: organic fertilizer + potassium silicate (K2O3Si); T4: NPK; T5: NPK + K2O3Si. The number of egg laying, eggs and nymphs of A. woglumi was evaluated in the basal, mid and apical strata of C. latifolia plants at 30, 60 and 90 days after fertilizer application. Reductions in the number of eggs and nymphs were observed in treatments with organic fertilization + K2O3Si and NPK + K2O3Si. Citrus latifolia plants treated with K2O3Si were less susceptible to A. woglumi and plants fertilized with NPK present higher susceptibility (p<0.05). There was a higher incidence of egg laying, eggs and 1st instar nymphs in the apical stratum and 2nd, 3rd and 4th instar nymphs in the basal and mid strata in C. latifolia (p<0.05). The addition of K2O3Si to organic and mineral fertilization is recommended as a viable alternative to reduce the population level of A. woglumi in citrus plants
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