Sordidus Population Research Articles

Analysis of Genetic Diversity of Banana Weevils (Cosmopolites sordidus) (Coleoptera: Curculionidae) Using Transcriptome-Derived Simple Sequence Repeat Markers.

The banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) is an economically important insect pest of bananas. It causes up to 100% yield losses and substantial lifespan reduction in bananas. Advances in genomics, proteomics, and sequencing technologies have provided powerful pathways to genotyping disastrous pests such as C. sordidus. However, such technologies are often not available to the majority of rural subtropical African banana growers and pest control managers. This study was therefore motivated by the need to create cheap and easily accessible C. sordidus genotyping methods that could be deployed by banana pest control managers to the benefit of C. sordidus control programs in the tropics where such advanced technologies are not readily accessible. We used an in-house C. sordidus transcriptome from the an-ongoing study from which we mined an array of simple sequence repeat (SSR) markers. Of these, six highly polymorphic transcriptome-derived SSR markers were used to successfully genotype within and among banana weevil population genetic diversity of 12 C. sordidus populations collected from four banana-growing agro-ecological zones (AEZs) in Uganda. The developed transcriptome-derived SSR markers can be used by researchers in population genetics for characterization of the C. sordidus and identification of new genes that are linked to traits of particular interest. The significant genetic diversity revealed in C. sordidus provides pertinent information for integrated pest management strategies.

Suitability of Cordyceps bassiana and Metarhizium anisopliae for biological control of Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) in an organic Mexican banana plantation: laboratory and field trials

The banana root borer [Cosmopolites sordidus Germar (Coleoptera: Curculionidae)] is the most harmful insect pest currently affecting organic banana plantations in Mexico. The use of entomopathogenic fungi to control C. sordidus populations is a biological control method that presents a promising alternative to conventional means. This study aimed to evaluate the virulence of native isolates of entomopathogenic fungi Cordyceps bassiana and Metarhizium anisopliae against C. sordidus adults under laboratory and field conditions. In laboratory assays, 12 isolates of C. bassiana and nine isolates of M. anisopliae were tested. In field trials, Cb174 (C. bassiana) and Ma148 (M. anisopliae) isolates and their co-application were evaluated. Cordyceps bassiana isolates Cb171 and Cb174 resulted in adult mortalities of 80.2 and 77.5% and had the lowest median lethal concentrations (LC50) of 6.4 × 106 and 5.4 × 106 conidia mL−1, respectively. Regarding the median lethal time (TL50), the most virulent isolates of C. bassiana were Cb171 and Cb190 with 9.49 and 9.55 days, respectively. For M. anisopliae, the Ma148 isolate was the most virulent (LC50 = 8.6 × 106 conidia mL−1 and LT50 = 12.61 days) and led to an adult mortality of 76.9%. In field trials, two tested isolates (C. bassiana Cb174 and M. anisopliae Ma148) were both able to reduce C. sordidus populations by 48.5% and their co-application by 38.1%. Percentage of mycosis in captured adults was over 50% for the entire evaluation period (1.6 months), which confirms the efficacy of entomopathogenic fungi. Both Cb174 and Ma148 are good candidates for developing formulated products to use in the integrated pest management of C. sordidus in Mexican organic banana plantations.

Reducing Cosmopolites sordidus populations and damage using traps baited with pheromone and plantain corm

The banana weevil Cosmopolites sordidus is an important pest in plantain and banana crops throughout the world. The objective was to evaluate a mass trapping system based on traps baited with synthetic pheromone (sordidin) + plantain corm tissue to reduce C. sordidus populations and damage in the Centro-Chontalpa region of Tabasco state, Mexico. The experiment was carried out on plots of about two to three hectares of Horn plantain Musa AAB infested by C. sordidus. Treatments were four traps ha-1, eight traps ha-1 and a control (without traps). Population density and damage in corms of small plants (suckers) were reduced after six months of mass trapping, while damage in corms of mature plants (freshly harvested) only decreased signi cantly after 13 months of trapping. By doubling the number of traps, the reduction in the C. sordidus population and damage was not signi cant. The use of four traps ha-1 baited with synthetic pheromone + plantain corm is a technically feasible strategy that provides at least partial control of this pest under local Horn plantain production conditions.

Combination of the fungus Beauveria bassiana and pheromone in an attract‐and‐kill strategy against the banana weevil, Cosmopolites sordidus

AbstractAn attract‐and‐kill approach based on pellets from soybean or palm stearin fats blended with the entomopathogenic fungus Beauveria bassiana (Bals.) Vuill. sensu lato and the aggregation pheromone sordidin (Cosmolure®) was tested against the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae). The viability of B. bassiana conidia, blended with hydrogenated oil and exposed for up to 150 min to heating at 50 °C, was not affected and the aggregation pheromone did not undergo any decomposition. Conidial viability in pellets decreased by 50% after an average of 15.1 and 9.1 days at 25 and 40 °C, respectively, when packaged in polypropylene bags. Active packaging (hermetic bag + O2/moisture‐absorbing sachet) increased the shelf lives almost 10 and 6 times at 25 and 40 °C, respectively. In olfactometer bioassays, fat pellets amended with pheromone (sordidin, 1% wt/vol) were highly attractive to C. sordidus adults for up to 15 days, after which the pheromone release rate had decreased by about 90% and pellets were no longer attractive. Pellets with pheromone and conidia were as attractive to C. sordidus as banana rhizomes, and considerably more attractive than pieces of pseudostem. In no‐choice experiments conducted in boxes, survival of insects exposed to fungus‐impregnated pellets was affected by fat type (soybean fat vs. palm stearin) and bioassay temperature (25 vs. 30 °C), with results favoring soybean fat pellets at the higher temperature (96.9% of mortality after 18 days and ST50 of 7.7 days). However, mortality levels were low (21.7% for soybean fat pellets) or very low (1–5% for palm stearin pellets) in choice experiments carried out at 25 °C when fungus‐impregnated pellets were applied before or after exposure of pseudostem residues to insects, respectively. The potential of this delivery system to manage C. sordidus populations and other insect pests (including those with cryptic habits) is discussed.

Torta de mamona no controle da broca-do-rizoma (Cosmopolites sordidus) em bananeira-Terra

Objetivou-se avaliar o efeito da torta de mamona sobre a infestação por Cosmopolites sordidus e o desenvolvimento de mudas de bananeira cultivar Terra. Avaliaram-se diferentes dosagens da torta de mamona (0 g, 12 g, 15 g, 18 g e 24 g) aplicadas a cada dois meses, a partir do plantio em mudas de bananeira dispostas num delineamento inteiramente casualizado, com dez repetições. Avaliou-se a evolução vegetativa das mudas pela altura da planta, pelo diâmetro do pseudocaule e pelo número de folhas verdes. Efetuou-se a infestação das plantas com 25 adultos de C. sordidus em cada muda. Os danos causados foram avaliados por meio da percentagem de galerias no rizoma, número de adultos vivos e mortos, número de larvas e número de pupas. Determinou-se também o efeito dos tratamentos sobre o valor de absorbância relativo ao teor de clorofila nas folhas por meio do uso de um clorofilômetro. Observou-se baixa infestação da broca-do-rizoma nas mudas tratadas com a torta de mamona. O crescimento e a absorbância foram afetados positivamente pela aplicação da torta de mamona. Assim, a torta de mamona reduz a população de C. sordidus nos rizomas de bananeira cv. Terra, favorece o crescimento das plantas e aumenta o valor de absorbância.

Impact of Cultural Practice on the Control of Cosmopolites sordidus in Banana and Plantain Communities in Ore, Odigbo Local Government Area, Ondo State, Nigeria

In a study of the assessment of the banana weevil, Cosmopolites sordidus in an environment that sustains high production of banana and plantain in Ondo State, Nigeria, low levels of C. sordidus population and infestation were discovered. Population surveys of the weevil were conducted in randomly selected crop plots near living homes ( 500m). Investigation was done by the use of trapping systems, dissections of cut decaying pseudo stems and culturing of immature stages of insects to adulthood. A total number of 23 C. sordidus ( Coleoptera: Curculionidae ) were collected from 50 sampled plots that showed 10% infestation. Number of near – living home infested plots 2 (4%) did not significantly differ (P > 0.05) from number of far-from living home 3 (6%) infested plots. The result of this study also showed that the number of the pest found in banana and plantain crops in plots near living homes 11 (47.83%) did not significantly differ (P > 0.05) from those in plots far from living homes 12 (52.17%). This suggests that site of crop plot has no obvious impact on the prevalence of C. sordidus in banana and plantain communities. In this study, the relationship between backyard / kitchen waste and the population of C. sordidus needs further investigation while the low population and infestation levels recorded strongly indicate cultural practice effect. Key words: Banana weevil, high production, population, living homes, trapping systems.

Mucuna deeringiana (Bort) Merr. y el picudo del cormo, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), en plátano

Se estudió el efecto de la leguminosa Mucuna deeringiana sobre la densidad poblacional y daño al cormo por Cosmopolites sordidus en plátano. Se estudiaron dos sistemas de siembra: mucuna intercalada y mucuna como cobertera verde. Se estudió además la relación de la densidad de adultos de C. sordidus y el daño por la larva al cormo. La presencia de M. deeringiana afectó la densidad de C. sordidus. Los datos sugieren que M. deeringiana atrae los adultos de C. sordidus, pero se requieren estudios adicionales para entender esta relación. La presencia de M. deeringiana no afectó la altura, diámetro del tallo, ni el número de hijos del plátano cuando la leguminosa se eliminó a los cuatro meses de sembrada. Sin embargo, el establecimiento y manejo de la leguminosa aumentó los costos de producción. A pesar de que la densidad de C. sordidus fue baja durante casi todo el año, se observaron dos picos poblacionales, uno entre noviembre y enero y otro entre junio y agosto. La densidad insectil alcanzó un nivel máximo de 3.5 insectos por trampa.