Odorant receptors (ORs) interface animals with airborne chemical signals. They are under strong selection pressure and are therefore highly divergent in different taxa. Yet, some OR orthologs are highly conserved. These ORs may be tuned to odorants of broad importance, across species boundaries. Two widely distributed lepidopteran herbivores, codling moth Cydia pomonella (Tortricidae) feeding in apples and pears, and the African cotton leafworm Spodoptera littoralis (Noctuidae), a moth feeding on foliage of a wide range of herbaceous plants, both express a receptor ortholog, OR19, which shares 58% amino acid identity and 69% amino acid similarity. Following heterologous expression in the empty neuron system of Drosophila melanogaster, we show by single sensillum recordings that CpomOR19 and SlitOR19 show similar affinity to several substituted indanes. Tests with a series of compounds structurally related to 1-indanone show that 2-methyl-1-indanone, 2-ethyl-1-indanone, 3-methyl-1-indanone and 1-indanone elicit a strong response from both ORs. A keto group in position 1 is essential for biological activity and so are both rings of the indane skeleton. However, there is an important difference in steric complementary of the indane rings and the receptor. Methyl substituents on the benzene ring largely suppressed the response. On the other hand, alkyl substituents at position 2 and 3 of the five-membered ring increased the response indicating a higher complementarity with the receptor cavity, in both CpomOR19 and SlitOR19. Our results demonstrate a conserved function of an odorant receptor in two moths that are phylogenetically and ecologically distant. It is conceivable that a conserved OR is tuned to signals that are relevant for both species, although their ecological roles are yet unknown. Our finding demonstrates that functional characterization of ORs leads to the discovery of novel semiochemicals that have not yet been found through chemical analysis of odorants from insects and their associated host plants.

The spotted wing Drosophila, Drosophila suzukii, has emerged within the past decade as an invasive species on a global scale, and is one of the most economically important pests in fruit and berry production in Europe and North America. Insect ecology, to a strong degree, depends on the chemosensory modalities of smell and taste. Extensive research on the sensory receptors of the olfactory and gustatory systems in Drosophila melanogaster provide an excellent frame of reference to better understand the fundamentals of the chemosensory systems of D. suzukii. This knowledge may enhance the development of semiochemicals for sustainable management of D. suzukii, which is urgently needed. Here, using a transcriptomic approach we report the chemosensory receptor expression profiles in D. suzukii female and male antennae, and for the first time, in larval heads including the dorsal organ that houses larval olfactory sensory neurons. In D. suzukii adults, we generally observed a lack of sexually dimorphic expression levels in male and female antennae. While there was generally conservation of antennal expression of odorant and ionotropic receptor orthologues for D. melanogaster and D. suzukii, gustatory receptors showed more distinct species-specific profiles. In larval head tissues, for all three receptor gene families, there was also a greater degree of species-specific gene expression patterns. Analysis of chemosensory receptor repertoires in the pest species, D. suzukii relative to those of the genetic model D. melanogaster enables comparative studies of the chemosensory, physiology, and ecology of D. suzukii.

The diamondback moth, Plutella xylostella (L.), is a worldwide pest of brassica crops, resistant to a large number of insecticides. As an alternative, the use of pheromone-baited traps has been proposed but farmers are yet to be convinced. In the present study, we aimed to validate the benefits of the use of pheromone-baited traps for monitoring and mass trapping in cabbage production in Central America as means of Integrated Pest Management (IPM) in comparison to calendarized insecticide sprays, which are the farmers’ current practices (FCP). Mass trapping was established in nine selected plots of cabbage in Costa Rica and Nicaragua. Average captures of males/trap/night, plant damage and net profits of these IPM plots were compared to simultaneously evaluated or historically reported FCP plots. The results indicate that in Costa Rica, trap captures did not justify the application of insecticides and average net profits increased by more than 11% when the trapping methods were implemented. In Nicaragua, IPM plots were able to reduce insecticide applications to one third of those in FCP plots. These results confirm the economic and environmental benefits of pheromone-based management of DBM in Central America.

Over the last decade, high-end fruits such as berries, have faced the impact of Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae) across Asia, Europe, and the Americas. Yet, none of the countries from Central America has officially reported this pest. We carried out surveys in the blackberry fields of Costa Rica. We placed a proprietary mixture of liquid attractants into red-cup traps with lateral holes, as it has been widely demonstrated as best to capture D. suzukii. Subsequently, we collected both adults and larvae for analysis. The adults were identified using key morphological features of D. suzukii, while the larvae were used for molecular analysis of the samples. The results revealed the first record of establishment of D. suzukii infesting blackberry in Costa Rica, Central America. These discoveries reveal the spread of the pest in Latin America and the importance of intensifying the surveillance process in other countries in this region.

The great diversity of specialist plant-feeding insects suggests that host plant shifts may initiate speciation, even without geographic barriers. Pheromones and kairomones mediate sexual communication and host choice, and the response to these behaviour-modifying chemicals is under sexual and natural selection, respectively. The concept that the interaction of mate signals and habitat cues facilitates reproductive isolation and ecological speciation is well established, while the traits and the underlying sensory mechanisms remain unknown. The larva of codling moth feeds in apple and other rosaceous fruits. We show for the first time that the response of male moths to female sex pheromone codlemone relies upon presence of pear ester, a kairomone emitted by host fruit. In the non-host tree birch, attraction to pheromone alone is very strongly reduced, but is fully rescued by blending pheromone with kairomone. This affords a mechanism how host plant shifts shape new mate-finding signals that can give rise to assortative mating and reproductive isolation.

Este artículo es producto del quehacer investigativo del Programa Perfiles, Dinámicas y Desafíos de la Educación Costarricense, del Centro de Investigación y Docencia en Educación de la Universidad Nacional y expone los principales resultados de un trabajo investigativo de carácter diagnóstico, con diferentes niveles de análisis: exploratorio, descriptivo y correlacional, que utilizó una estrategia mixta de triangulación concurrente, vinculando métodos cuantitativos y cualitativos. Participaron como informantes exministros del Ministerio de Educación Pública (MEP), directores regionales de educación, directores de colegios públicos, privados, subvencionados, urbanos, rurales, especialistas en evaluación, representantes gremiales, docentes y estudiantes. Se realizaron entrevistas semiestructuradas y encuestas, se utilizaron los datos estadísticos del MEP sobre el rendimiento estudiantil en las pruebas de bachillerato, registros de carácter sociodemográfico y socioeducativo e índices sociales asociados a la población examinada. El análisis de los datos refleja algunos aspectos trascendentales en materia de equidad, inclusión educativa y condiciones de desarrollo social, a tomar en consideración para la interpretación de los resultados de las Pruebas Nacionales de Bachillerato en la Educación Media en Costa Rica.