Sugarcane stem borers of the genus of Diatraea (Lepidoptera: Crambidae) form a species complex that causes serious economic losses to sugarcane production in the Cauca River Valley and other regions of Colombia. Two primary species, Diatraea saccharalis (F.) and D. indigenella Dyar and Heinrich, have been effectively managed for more than 4 decades through augmentative releases of the tachinid flies Lydella minense (Townsend) and Billaea claripalpis (Wulp) (Diptera: Tachinidae) and the egg parasitoid Trichogramma exiguum Pinto & Platner (Hymenoptera: Trichogrammatidae). Here we review the current pest status of Diatraea species, damage assessment protocols, management tactics, and the environmental factors and cultural practices that can affect biological control outcomes. Recent changes in the cultivars grown have the potential to increase pest populations and diminish biological control efficacy. Additionally, recent outbreaks of new Diatraea species may further increase overall pest pressure. Thus, there is a need to develop supplementary tactics for the management of these pests that will be compatible with biological control, as well as more reliable protocols for assessing host plant resistance against the increase in infestation intensity.

No abstract

No abstract

S U M M A R YThe presence of free water on both surfaces of the leaves of shaded and unshaded coffee trees was evaluated at Cenicafe, Colombia. Rainfall was the main source of humidity and dew was not registered during the experiment. Five mm of rain caused canopy saturation and water began to reach the underside of the leaves. The period of wetness lasted 9.7 hours on average and no significant moisture differences were found between leaves on east or west facing branches, at different levels within the tree, or externally or internally positioned on the branches, either for exposed or shaded trees. Between 1700 and 0500 h (local time), a close relation was found between the time of rain initiation and the duration of the period of wetness. Leaves dried out at approximately 1000 h.O. Guzman y L. Gomez: La permanencia del agua libre en hojas de cafe.R E S U M E N La presencia de agua libre en ambas superficies de las hojas de cafetos sombreados y no sombreados fue evaluada en Cenicafe, Colombia. La fuente principal de la humedad era la Uuvia, y no se registro roci'o durante el experimento. El follaje se saturo con 5 mm de Uuvia, y el agua comenzo a alcanzar la parte inferior de las hojas. El periodo de humedad duro un promedio de 9,7 horas, y no se vieron diferencias significativas en la humedad entre hojas de ramas de orientacion este u oeste a diferentes niveles dentro de la planta, o de posicion externa o intema en las ramas, ni para plantas expuestas ni sombreadas. Entre las 1700 y 0500 h (hora local), se vio una relacion estrecha entre el momento del comienzo de la Uuvia y la duracion del periodo de humedad. Las hojas se secaron a las 1000 h (hora local) aproximadamente.Coffee leaf rust (Hemileia vastatrix Berk, and Br.) was first detected in Colombia in September 1983. This event, a real threat to the Colombian economy, created a need for research into the different aspects concerning the development of the fungus.Climatic conditions can affect the geographical distribution and seasonal severity of plant diseases. Therefore, a knowledge of the conditions prevailing during the course of a specific disease can lead to a better understanding of its nature and behaviour and at the same time contribute to more economic and efficient control. Although the relation between climate and disease is complex, there are two stages in the life cycle of the majority of pathogenic fungi that are very susceptable to environmental conditions, namely: spore dispersion which requires a minimal amount of water, and spore germination which is a function of temperature and humidity (Waller, 1973).

No abstract

Bean plants (Phaseolus vulgaris L.) variety Diacol‐Calima, were protected with insecticides from Empoasca kraemeri R. & M. attack during various growth stages. When the leafhopper attack occurred late in the growing season, the most critical period for control was from 45–62 days after planting. When leafhopper attack was severe during the entire growing season, the period from 27–44 days was most critical, followed in importance by the 45–62‐day period. Insecticidal control before 27 days and after 62 days after planting did not influence final seed yield. Leafhopper attack affected four components of yield, i.e., (1) by reducing the number of pods per plant, (2) number of seeds per pod, (3) 100‐seed weight, and (4) number of empty pods per plant. ZUSAMMENFASSUNG DER EINFLUSS VON ZIKADENBEFALL (EMPOASCA KRAEMERI) WÄHREND VERSCHIEDENEN WACHSTUMSSTADIEN DER BOHNE (PHASEOLUS VULGARIS) AUF DEN SAMENERTRAG Zikaden, deren wichtigste Art Empoasca kraemeri ist. sind die bedeutendsten Bohnenschädlinge in Lateinamerika. Es wurden zwei Experimente durchgeführt um festzustellen, in welchem Wachstumsstadium der grösste Schaden auftritt. Dazu wurde der Wachstumszyklus in vier Abschnitte unterteilt, beginnend 8 Tage nach der Saat. Die Pflanzen wurden in den verschiedenen Wachstumsstadien mit Monocrotophos (0.05%) behandelt oder zum Vergleich unbehandelt gelassen. Die Insektenpopulationen der Adulten und der Larven wurden wöchentlich (1. Experiment) und zweimal wö;chentlich (2. Experiment) gemessen. Die Bohnen, die in der Zeit zwischen 8 und 26 Tagen nach der Pflanzung und nach 62 Tagen ohne Insektizidschutz gelassen wurden, erbrachten den gleichen Ertrag wie die Bohnen, die über alle vier Wachstumsstadien geschützt wurden. Im ersten Experiment, in dem der Befall durch Zikaden erst spät einsetzte, war die Zeitspanne zwischen 45 und 62 Tagen besonders kritisch. Im zweiten Experiment, in dem der Insektenbefall schon vom Saatzeitpunkt an stark war, waren die Pflanzen in der Zeitspanne von 27–44 Tagen besonders gefährdet, gefolgt von der Periode von 45–62 Tagen. Im zweiten Experiment waren alle Ertragskomponenten vom Insektenbefall beeinflusst. Der Ertrag war streng mit dem 100‐Samengewicht korreliert. Wenn man zwei Ertragskomponenten berücksichtigt. war der Ertrag sehr streng korreliert mit der Anzahl voller und Prozent leerer Hülsen pro Pflanze.

Ten common bean genotypes (Jamapa, APN18, Carioca, Río Tibají, Porrillo, Pot 51, Bat 271, Bolita 42, Calima y CC25-9N) were grown in an intensively aereated nutritive solution with 5 weekly doses of phosphorus (0; 62,5; 125; 187,5 and 1875 mM/plant) and 2 mM of N in the form of KNO3. The objective was to evaluatefoliar biomass and its P content, as well as, to calculate the P Use Efficiency (PUE) parameter based on these and relate them with the concentration levels with which plants were nourished. The optimum requirement level obtained fromboth biomass and PUE criteria ranged between 62,5 - 187,5 mM/plant/week; this supported differences for P nutrition within the genera. Pot 51 showed the lowest requirement and Carioca the highest for optimum yielding; but Bat 271 exhibited the highest efficiency index even at a suboptimum level. Among these genotypes, CC25-9N showed the lowest efficiency and Porrillo showed no variation for this parameter. It may be concluded that the highest efficiency point coincided in 80 % of the cases with the maximum biomass production point.

En el Valle del Cauca (Colombia), se estudió la distribución e identificación de las especies más abundantes de crisópidos en zonas donde se cultiva la caña de azúcar (Saccharum spp.) con mayor intensidad. Así, se han determinado las especies que podrían ser utilizadas para contrarrestar el efecto del pulgón amarillo Sipha flava (Hemiptera: Aphididae) sobre la producción total de la caña de azúcar. Aunque las especies y morfotipos del presente estudio son separados utilizando caracteres morfológicos, se evaluó la validez de dichos caracteres. Para esto, se realizó una diferenciación morfológica mediante genitalia interna y una diferenciación molecular, empleando la técnica PCR-RFLP sobre la región 18S del ADN ribosomal, de 11 especies de tres géneros de la familia Chrysopidae (Ceraeochrysa, Chrysoperla y Leucochrysa), algunas de las cuales podrían ser importantes como agentes de control biológico del pulgón amarillo de la caña de azúcar, S. flava. Los caracteres empleados resultaron ser útiles para distinguir las especies. En el caso de la genitalia interna, mostraron diferentes patrones de las estructuras. En el caso de los datos moleculares, las especies fueron diferenciadas utilizando solo una combinación de iniciadores NS para la amplificación del ADN y la digestión del amplificado producida con una enzima de restricción (NS5-NS6+DraI). Esta información se adiciona al conocimiento taxonómico que se tiene sobre la familia, además puede ayudar a resolver problemas sistemáticos al interior de los géneros.