Patogenecidad de hongos entomopatógenos en termitas en plantaciones de Moringa oleífera, Posoltega Nicaragua

Las termitas son plagas de importancia económica en sistemas agroforestales y agrícolas. La investigación se realizó en el Centro de Referencia Fidel Castro Ruz del Instituto Tecnológico Agropecuario del municipio de Posoltega en convenio con la UNAN-LEON. El objetivo fue determinar la incidencia e identificar la especie de termitas presente en la plantación Moringa oleífera y evaluar la patogenicidad de hongos entomopatógenos en condiciones de campo. La investigación es de tipo cuasi experimental, se evaluaron 3 tratamientos Beuveria bassiana con una concentración de 3.6 x 107 conidias/ml, Metarhizium anisopliae con una concentración de 2.28 x 106 conidias/ml y tratamiento químico (Cipermetrina), dosis de 6cc/ litro de agua. En una población de 16 plantas con colmenas de termitas por tratamientos para un total de 48 unidades experimentales. La aplicación de los tratamientos se realizó mediante la perforación de cada colmena, en sus cuatro puntos cardinales (norte, sur, este y oeste) asperjando con una bomba de mochila manual. La eficacia se determinó mediante la fórmula de la efectividad biológica. El 39% de población de marango Moringa oleífera se encontró infectada por termitas. La especie de termitas presente en las plantaciones Moringa oleífera fue Nasutitermes corníger. La efectividad de los tratamientos presentó sig. Estadística (P= 0.000) siendo Cipermetrina que presento los mejores porcentaje de efectividad con valores promedios de 96% seguido por M. anisopliae con efectividad de 24 % y B. bassiana con 7%. Los porcentajes de esporulación presentaron sig. Estadística. (P= 0.0033) B. Bassiana con un 31% y M. anisopliae presento 69%.

Preliminary Predictive Model of Termiticidal and Repellent Activities of Essential Oil Extracted from Ocotea quixos Leaves against Nasutitermes corniger (Isoptera: Termitidae) Using One-Factor Response Surface Methodology Design

Termites are one of the most challenging pests that agriculture and urban environments are faced with. They bring substantial losses in annual and perennial crops and damage wood components at construction sites. The development of natural products with biological activity for termite control is an ecological alternative in the search to replace conventional products. Hence, the aim of this research was to predict the termiticidal and repellent effects of the essential oil from Ocotea quixos leaves on Nasutitermes corniger using a one-factor response surface methodology design. The variable analysed was the concentration of essential oil in ethanol at an interval of 0.3–0.05% for anti-termite activity and between 0.12 and 0.01% for repellent action. A 100% mortality rate was found at concentrations higher than 0.12% and at the minimum concentration analysed, the effect was 22.2%. As for the repellent action, the concentration of 0.12% was able to repel 100% of the termites and at 0.01% it repelled 48.9%. The analysis of the essential oil from Ocotea quixos leaves by GC-MS resulted in the presence of 42 compounds, 39 of them elucidated. The main compounds were (E)-cinnamyl acetate (36.44%), (E)-cinnamaldehyde (27.03%), (E)-β-caryophyllene (5.21%) and (E)-methyl isoeugenol (4.18%).

Diversity structure of the microbial communities in the guts of four neotropical termite species

The termite gut microbiome is dominated by lignocellulose degrading microorganisms. This study describes the intestinal microbiota of four Argentinian higher termite species with different feeding habits: Microcerotermes strunckii (hardwood), Nasutitermes corniger (softwood), Termes riograndensis (soil organic matter/grass) and Cornitermes cumulans (grass) by deep sequencing of amplified 16S rRNA and ITS genes. In addition, we have performed a taxonomic and gut community structure comparison incorporating into the analysis the previously reported microbiomes of additional termite species with varied diets. The bacterial phylum Spirochaetes was dominant in the guts of M. strunckii, N. corniger and C. cumulans, whereas Firmicutes predominated in the T. riograndensis gut microbiome. A single bacterial genus, Treponema (Spirochaetes), was dominant in all termite species, except for T. riograndensis. Both in our own sequenced samples and in the broader comparison, prokaryotic α-diversity was higher in the soil/grass feeders than in the wood feeders. Meanwhile, the β-diversity of prokaryotes and fungi was highly dissimilar among strict wood-feeders, whereas that of soil- and grass-feeders grouped more closely. Ascomycota and Basidiomycota were the only fungal phyla that could be identified in all gut samples, because of the lack of reference sequences in public databases. In summary, higher microbial diversity was recorded in termites with more versatile feeding sources, providing further evidence that diet, along with other factors (e.g., host taxonomy), influences the microbial community assembly in the termite gut.

Influence of the amount of food resources in the foraging behavior of Nasutitermes corniger (Motschulsky)

Food scarcity or abundance are factors regulating termites’ foraging behavior in general. The aim of the present study is to evaluate the influence of four amounts of Eucalyptus grandis on foraging behavior events shown by worker and soldier of Nasutitermes corniger during laboratory tests. The tests were carried out with adult and active N. corniger colonies found in nests collected in the field, which were stored in glass cubes connected to the test arenas. Four different amounts of wood blocks were used in the tests and each amount concerned a treatment and defined a different experimental group: 1, 2, 3 and 4 blocks/arenas, with 5 repetitions. Each test lasted 60 minutes and consisted in observing, or not, the occurrence of behavioral events shown by foragers when they had contact with the treatment. The duration of each event was recorded, whenever it was observed. The number of recruited foragers and the number of workers consuming the blocks were recorded at the end of each test applied to each treatment. Nasutitermes corniger presented the three behavioral events in all treatments; however, there was not significant difference between treatments in the occurrence of the two first events, in the time taken from test start to the occurrence of a new event, in the number of recruited termites and in the number of gnawing workers. Only workers’ mass recruiting was influenced by the amount of wood available. The occurrence of this event was significantly higher in treatments with greater amounts of wood. Thus, N. corniger adjusts its mass recruitment behavior in response to available food amount, which should be considered when developing baiting system for its control.

Riqueza e composição de Térmitas (Blattodea, Isoptera) em manguezais do litoral amazônico

Among the varieties of insects present in mangroves, termites can easily colonize mangrove forests by their winged forms, and thus, build arboreal nests. In view of the presence of this order in mangroves, this work presents the results of a sampling of Termites (Blattaria, Isoptera) in mangrove forests on the Amazon coast, as well as highlighting ecological aspects of these insects. Two collections were carried out during an annual cycle (dry and rainy) at six sampling sites located in the mangroves of Soure on Marajó Island, Pará. In each sampling site, a 100 mx 3 m transection was delimited, subdivided into 10 plots of land. 5 mx 3 m, with an interval of 5 m between each plot, with a sampling effort of 1h / person in each plot in search of termites in the different microhabitats present in the mangrove. A total of seven species distributed in three genera and three families were found over an annual cycle. The most abundant species were Nasutitermes corniger (Motschulsky, 1855) (38.70%), Nasutitermes nigriceps (Haldeman, 1853) (25.00%) and Nasutitermes surinamensis (Holmgren, 1910) (20.16%). The xylophagous termites were dominant and the dry season the number of species and specimens was higher.