Actividad fagodisuasiva de las plantas Tithonia diversifolia y Montanoa hibiscifolia (Asteraceae) sobre adultos del insecto plaga Bemisia tabaci (Homoptera: Aleyrodidae)

Abstract

Phagodeterrent activity of the plants Tithonia diversifolia and Montanoa hibiscifolia (Asteraceae) on adults of the pest insect Bemisia tabaci (Homoptera: Aleyrodidae). Bemisia tabaci (Gennadius) is a polyphagous, cosmopolitan and worldwide relevant pest, mainly acting as a virus vector on many crops. A sound preventive approach to deal with it would be the application of repellent or deterrent substances hopefully present in tropical plants, which in turn may contribute to take advantage of the remarkable rich Mesoamerican biodiversity. Therefore, extracts of two wild plants belonging to family Asteraceae, titonia (Tithonia diversifolia) and "tora" (Montanoa hibiscifolia), were tested for phagodeterrence to B. tabaci adults. The crude leaf extract of each one, as well as four fractions thereof (hexane, dichlorometane, ethyl acetate, and methanol) were tested under greenhouse conditions; in addition, the extracts were submitted to a phytochemical screening to determine possible metabolites causing phagodeterrence. Both restricted-choice and unrestricted-choice experiments were conducted. In the former ones, each fraction was tested at four doses (0.1, 0.5, 1.0 and 1.5% v/v), which were compared with four control treatments: distilled water, endosulfan, an agricultural oil (Aceite Agrícola 81 SC), and the emulsifier Citowett. Tomato plants were sprayed and placed inside sleeve cages, where 50 B. tabaci adults were released. The criterion to appraise phagodeterrence was the number of landed adults on plants at 48h. For the unrestricted-choice experiments, only the two highest doses (1.0 and 1.5%) of the crude extracts of each species were tested, and compared to distilled water and the agricultural oil. The titonia and "tora" crude extracts caused phagodeterrence, and for both plant species the methanol fraction stood out. Results suggest that metabolites causing phagodeterrence are several sesquiterpenic lactones, polyphenolic compounds (flavonoids and tannins) and saponins.

Invasive weeds with pesticidal properties as potential new crops

“…Furthermore, in order to reflect common bean growing practices in Tanzania, half of the farmers 20planted beans as a mono-crop whilst the other half (20) planted beans as an intercrop with maize (Zea mays). These six species were chosen due to their wide abundance around farms, roadsides and bushland, their familiarity to farmers and considerable existing knowledge on their efficacy, bioactive constituents and safety (Adedire and Akinneye, 2004;Adeniyi et al, 2010;Ambrósio et al, 2008;Asawalam et al, 2008;Bagnarello et al, 2009;Belmain et al, 2012;Gadzirayi et al, 2009;Ganjian et al, 1983;Gu et al, 2002;Kawuki et al, 2005;Madzimure et al, 2011;Mujovo et al, 2008;Oyewole et al, 2008;Pereira et al, 1997;Stevenson et al, 2012;Viljoen et al, 2005). To ensure uniformity, the leaves from each seasonal collection were mixed together for each species before drying.…”

Desempeño agronómico y valor nutritivo de Tithonia diversifolia (Hemsl.) A Gray para la alimentación de bovinos

“…Diferentes autores reportan que existen especies arbóreas y arbustivas que además de ser fuente de alimento para animales, pueden ser utilizadas como combustible, y material de construcción (35), biocontroladores de plantas e insectos (36,37), fitorremediadores de suelos (38,39), coadyuvantes en la detención de la erosión, mejoradores de la fertilidad y rendimiento de cultivos como maíz (40), arroz (41), yuca (42), pasto elefante (P. purpureum) (43), encontrándose dentro de este grupo Tithonia diversifolia. Esta especie posee una cantidad apreciable de nutrientes y produce abundante materia seca por unidad de área, la cual se descompone rápidamente en el suelo convirtiéndose en una fuente de nutrientes para las plantas (44), aumentado de forma significativa el rendimiento y la calidad de los cultivos.…”

Aktivitas Antifeedant dan Antioviposisi Ekstrak Daun Tithonia terhadap Kutu Kebul

“…Upaya pemenuhan standar tersebut dapat dilakukan dengan menggunakan pestisida atau insektisida nabati. Insektisida nabati merupakan alternatif pengembangan pengendalian hama dan penyakit yang murah, ramah lingkungan dan mudah didapatkan dengan cara memanfaatkan keanekaragaman flora yang melimpah (Oyedokun et al 2011 (Bagnarello et al 2009). Bunga, daun, batang dan akar Tithonia mengandung minyak atsiri.…”

“…Analisis data dilakukan dengan menggunakan One-Way ANOVA dengan taraf 5% dan apabila terdapat beda nyata dilanjutkan dengan uji DMRT 5%. Bagnarello et al (2009), menggunakan metode ekstraksi maserasi dengan menggunakan pelarut 70% etanol dan menggunakan metode no-choice test untuk menentukan antifeedant dan anti-oviposisi dengan waktu pengamatan 48 jam.…”

“…Perilaku tersebut menunjukkan bahwa kutu kebul menghindari daun yang telah diaplikasi ekstrak Tithonia karena adanya kandungan senyawa metabolit sekunder. Hal ini sesuai dengan penyataan Bagnarello et al (2009), bahwa kriteria penentu aktivitas antifeedant adalah jumlah hinggapan kutu kebul dewasa pada bagian tanaman yang telah diaplikasi sesuai perlakuan. Metabolit sekunder yang terdapat dalam Tithonia berupa sesquiterpene laktone, senyawa polifenol berupa flavonoid dan tannin berperan sebagai antifeedant.…”