In Vitro Evaluation of Acute Toxicity of Five Citrus spp. Essential Oils towards the Parasitic Mite Varroa destructor

Varroa destructor is the most important ectoparasitic mite of honey bees that has a negative impact on bee health and honey production. The control programs are mainly based on the use of synthetic acaricides that are often administered indiscriminately. All this has led to drug resistance that now represent a great concern for honey bee farming. The research for alternative products/methods for mites’ control is now mandatory. The aim of this study was to test whether Citrus spp. essential oils could diminish the growth of the V. destructor mite. In Calabria (southern Italy), plants of the Citrus genus are very common and grow both spontaneously and cultured. The essential oils used in this study were extracted from bergamot (Citrus bergamia), grapefruit (Citrus paradisi), lemon (Citrus limon), orange (Citrus sinensis), and mandarin (Citrus reticulata) by hydrodistillation. Every EO was in vitro tested against V. destructor. Each experimental replicate was performed using 35 viable adult female mites (5 for each EO) collected the same day from the same apiary and included negative controls (5 individuals exposed to acetone only) and positive controls (5 individuals exposed to Amitraz diluted in acetone). The essential oils (Eos) were diluted (0.5 mg/mL, 1 mg/mL, and 2 mg/mL) in HPLC grade acetone to obtain the working solution to be tested (50 µL/tube). Mite mortality was manually assessed after 1 h exposure under controlled conditions. The essential oils that showed the best effectiveness at 0.5 mg/mL were bergamot, which neutralized (dead + inactivated) 80% (p ≤ 0.001) of the parasites; grapefruit, which neutralized 70% (p ≤ 0.001); and lemon, which neutralized 69% of them. Interestingly, the positive control (Amitraz) at the same concentration neutralized 60% of the parasites. These results demonstrate that Calabrian bergamot, grapefruit, and lemon Eos consistently reduced V. destructor viability and open the possibility for their utilization to control this parasite in honey bee farming.

Plagas asociadas a los cítricos en Chinandega, Nicaragua, 2018

Los cítricos (Citrus spp. L.) representan en Nicaragua una fuente de divisa y generación de empleo porque, no existe un reporte formal sobre la ocurrencia poblacional de insectos asociados a los cítricos. El presente estudio tuvo el propósito de determinar la fluctuación poblacional de insectos plagas y benéficos en cítricos. El estudio se realizó en los municipios de Chinandega y Chichigalpa, departamento de Chinandega, en el período de abril a septiembre del 2014, el levantamiento de datos fue en seis fincas, en cada finca se ubicaron seis trampas, tres trampas de caída libre (Pitfall traps) para la captura de insectos rastreros, y tres trampas de galón con melaza para la captura de insectos voladores, los insectos colectados se enviaron al laboratorio de entomología de la UNA para su identificación hasta el nivel de especie, se evaluó el número de insectos por familia y a los datos se le realizó un análisis de varianza, la diversidad y abundancia se estimó utilizando el índice de diversidad Shannon-Weaver, para las diferentes familias de la población. Los resultados obtenidos demostraron que las principales familias de insectos asociados al cultivo de cítricos son, Formicidae, Syrphidae, Vespidae, Tachinidae, Carabidae, Apidae, Tenebrionidae, Chrysopidae, Sarcophagidae y de los arácnidos se encontró a la familia Araneidae, se concluye que La mayor riqueza de insectos asociados a los cítricos fue encontrada en la finca Farid seguida de las fincas Mariaelsa y Pañueleta, esto es debido a baja aplicación de pesticida, presencia de abundante vegetación silvestre y cercanía con otras especies de cultivadas en la zona .

Unusual Stylar-End Breakdown and Sour Rot on Key Lime (Citrus aurantiifolia) in Pre-Harvest Condition in Italy

Key lime (Citrus aurantiifolia) is an emerging crop in Italy, especially in the Southern regions, where the environmental conditions are suitable for its cultivation. A field survey in Sicily in a commercial orchard of Key lime revealed the widespread presence of water-soaked spots and sunken/dry lesions at the stylar-end, mainly in pre-harvest condition. Water-soaked spots were attributed to Geotrichum citri-aurantii, an agent of sour rot on Citrus spp., whereas the sunken/dry lesion was attributed to the physiological disorder known as stylar-end breakdown. Sour rot and stylar-end breakdown are usually considered post-harvest diseases and rarely found in the field on fruit still attached to the tree. Although Geotrichum citri-aurantii is not responsible for the stylar-end breakdown, its association with this alteration reveals the importance of the environmental conditions and the agronomic practices in diseases/disorders development. In addition, to our knowledge, this is the first report of Geotrichum citri-aurantii on Key lime in Europe.

Các phương pháp tạo màng bảo quản trái cây họ cam quýt

Cam qu‎‎ýt (Citrus spp., Rutaceae) là họ cây ăn trái có vai trò rất quan trọng trong thành phần thực phẩm của con người. Sau khi thu hoạch, trái cây thường bị thay đổi sinh lý‎, mất khối lượng, dễ nhiễm bệnh làm hư hao cũng như làm giảm chất lượng của trái ảnh hưởng rất lớn đến kinh tế. Các bệnh xảy ra với trái cam quý‎t chủ yếu là do các loại nấm bệnh trên cây gây ra như: Penicillium digitatum, Penicillium italicum, Colletotrichum, Lasiodiplodia, Phomopsis, Alternaria và Phytophthora. Do vậy để bảo quản trái, các loại màng polymer sinh học hoặc tổng hợp để bao phủ trái thường được sử dụng nhằm ngăn cản sự tấn công của mầm bệnh, ngoài ra để tăng cường khả năng chống nhiễm bệnh của trái, có thể bổ sung vào màng bao phủ trái các chất kháng nấm bệnh an toàn được cho phép là các hóa chất tổng hợp hoặc chiết xuất từ tự nhiên có thể ăn được. Bài viết này trình bày các công trình bảo quản trái bằng phương pháp tạo màng đã được nghiên cứu và ứng dụng cho đến nay để đảm bảo chất lượng quả cam sau thu hoạch.

Pseudocercospora angolensis (leaf spot of Citrus spp.).

P. angolensis is a dematiaceous hyphomycete occurring in sub-Saharan Africa and Yemen. This fungus requires moisture for infection and the production of wind-borne conidia and causes a devastating fruit and leaf spot disease of cultivated species of Citrus. Losses of 50-100% of yield can occur and growers may cease production where the disease is endemic. Although species and cultivars of Citrus vary in susceptibility, no source of resistance is known (Kuate, 1998). An A1 quarantine pest for Europe and the Mediterranean region (EPPO, 2009), this fungus is also of concern for other warm humid regions where citrus is grown, such as Florida, USA. Other than by wind, conidia can be transported on infected fruit or propagated material.