Número de ciclos cortos necesarios para inducir la diapausa en huevos y larvas de Sesamia nonagrioides (Lefebvre)

Se sometieron huevos de Sesamia nonagrioides (LEFEBVRE) durante su desarrollo embrionario a fotoperiodo corto 12:12 (L:O) y posteriormente a fotoperiodos 16:8 y 0:24, sin observar que se hubiera inducido diapausa en ellos. Las larvas neonatas sometidas a 1, 2, 3, 4 ó 5 ciclos cortos (12:12) no manifestaron diferencias en la duración del desarrollo respecto de las larvas sometidas a fotoperiodo 16:8 y por tanto no manifestaron diapausa. Las diferencias de desarrollo se manifestaron cuando las larvas neonatas se sometieron a 8 ó más ciclos cortos (12:12), por lo tanto, fueron necesarios 8 ó mas ciclos cortos para inducir la diapausa en las larvas neonatas.Sesamia nonagrioides eggs were submitted during their embryonic development to short photoperiodic cycles (12:12) and after that to long photoperiodic cycles (16:8) and 0:24 without observing diapause induction in them. Neonate larvae submitted to 1,2, 3, 4 or 5 short cycles (12:12) didn't show differences in duration of development with regard to the larvae submitted to 16:8. Hence, they didn't show diapause induction. Differences in the duration of development were shown when neonate larvae were submitted to 8 or more short cycles. So, 8 or more short cycles were needed to induce diapause in neonate larvae

Abundance of Sesamia nonagrioides

Organisms inhabiting seasonal environments are able to synchronize their life cycles with seasonal cycles of biotic and abiotic factors. Diapause, a state of low metabolic activity and developmental arrest, is used by many insect species to cope with adverse conditions. Sesamia nonagrioides is a serious pest of corn in the Mediterranean regions and Central Africa. It is multivoltine, with two to four generations per year, that overwinters as mature larva in the northern of the Sahara desert. Our purpose was to compare the response of the S. nonagrioides populations occurring in the broader circum-Mediterranean area, with particular attention to the diapause period and the different numbers of generations per season. To this end, we tried to determine whether populations in the area differ in their response to photoperiod and whether we can foresee the number of generations in different areas. We present a model for predicting the occurrence of the critical photoperiod according to latitude and temperature and the spread of S. nonagrioides in the circum-Mediterranean countries. Responses of populations to short-day length suggest that the spread of the species is associated with a gradual loss of diapause in the southern areas, and that diapause incidence is positively correlated with latitude

Vuelos de la defoliadora de maíz, pastos y céspedes, Mythimna (Pseudaletia) unipuncta (Haworth) en la zona de Lleida

Mythimna unipuncta causa daños en gramíneas cultivadas (principalmente maíz) y céspedes cuya importancia ha ido aumentando los últimos años. En nuestra región presenta cuatro vuelos de adultos. Los daños causados por la descendencia del primer y cuarto vuelo no han sido apreciables, mientras que la descendencia del segundo vuelo ha causado daños de consideración en algunos campos de maíz y la del tercero en céspedes públicos. Se han calculado los grados -día necesarios para completar cada generación en campo y en el laboratorio. Se ha observado que casi todas las hembras capturadas del cuarto vuelo estaban apareadas y habían depositado sus huevos.Mythimna unipuncta causes damages in gramineous tillage plants (mainly maize) and lawns, which importance has increased in the last years. In our region the species shows four nights of adults. Damages caused by the offspring of the first and fourth flight have not been noticeable. Offspring of the second generation of adults has produced noticeable damages in some maize crops and offspring of the adults of the third flight has produced damages in public lawns. Degree-days necessaries for each complete generation have been calculated in field and in laboratory. Nearly all females of the fourth flight caught in light traps were mated and had laid their eggs

Survey of Natural Enemies of the Invasive Boxwood Moth Cydalima perspectalis in Southwestern Mediterranean Europe and Biocontrol Potential of a Native Beauveria bassiana (Bals.-Criv.) Vuill. Strain

Cydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia, has been especially devastating in the Mediterranean region and Catalonia, northeast Spain, where Buxus sempervirens is an essential component of the natural forest. As an invasive species, the lack of biotic mortality factors in the arrival region has been one of the main factors allowing its expansion. Therefore, this study aimed to collect and identify possible indigenous natural enemies adapting to the new species in the boxwood of the southwest Mediterranean region. Later, the efficacy of some of the collected species for controlling C. perspectalis larvae was tested in laboratory conditions. The larval collection was carried out in successive years in the boxwood of the region. Several collected larvae were infected with an entomopathogen, Beauveria bassiana, or parasitized by Compsilura concinnata, both common in native Lepidoptera caterpillars. The B. bassiana strain was found to be highly virulent against the developed larvae of C. perspectalis, which suggests that B. bassiana may be an effective treatment in parks and gardens when the first overwintering larvae are detected. The biology of the parasitoid identified is not very well known in Europe, which suggests the necessity of studying its biology and alternative hosts in the region in order to improve its population