Assessment of insecticide resistance in eggs and neonate larvae of Cydia pomonella (Lepidoptera: Tortricidae)

Spanish Cydia pomonella (L.) field populations have developed resistance to several insecticide groups. Diagnostic concentrations were established as the LC90 calculated on a susceptible strain (S_Spain) for five and seven insecticides and tested on eggs and neonate larvae field populations, respectively. The three most relevant enzymatic detoxification systems (mixed-function oxidases (MFO), glutathione S-tranferases (GST) and esterases (EST)) were studied for neonate larvae. In eggs, 96% of the field populations showed a significantly lower efficacy when compared with the susceptible strain (S_Spain) and the most effective insecticides were fenoxycarb and thiacloprid. In neonate larvae, a significant loss of susceptibility to the insecticides was detected. Flufenoxuron, azinphos-methyl and phosmet showed the lowest efficacy, while lambda-cyhalothrin, alpha-cypermethrin and chlorpyrifos-ethyl showed the highest. Biochemical assays showed that the most important enzymatic system involved in insecticide detoxification was MFO, with highest enzymatic activity ratios (5.1–16.6 for neonates from nine field populations). An enhanced GST and EST activities was detected in one field population, with enzymatic activity ratios of threefold and fivefold for GST and EST, respectively, when compared with the susceptible strain. The insecticide bioassays showed that the LC90 used were effective as diagnostic concentrations. Measures of MFO activity alongside bioassays with insecticide diagnostic concentrations could be used as tools for monitoring insecticide resistance in neonate larvae of C. pomonella.

Predation on common tern eggs by the yellow-legged gull at the Ebro Delta

The Ebro Delta holds a large seabird community, including a common tern (Sterna hirundo) local population of 3,085 pairs in 2000 which breeds scattered in several colonies. At El Canalot colony, 1,178 (1999) and 1,156 pairs (2000) of this species bred distributed in 32 and 38 sub-colonies respectively. These sub-colonies varied in size from 1 to 223 pairs and were placed near the main breeding colonies of yellow-legged gulls (Larus cachinnans) and Audouin´s gulls (L. audouinii), which are potential egg-predators of terns. We studied egg predation during 1999 (6 sub-colonies) and 2000 (27 sub-colonies). Overall, we found that 10.6% of the nests in 1999 and 16.7% in 2000 suffered partial or total egg predation, being total in 81.1% of the predatory events. Predation was significantly higher in small sub-colonies (< 11 pairs): 49.4% in 1999 and 75.5% in 2000. Only attacks from yellow-legged gulls were observed, and defence behaviour of terns was significantly more frequent against this gull species (40.5 hours of observation), suggesting that in most cases the egg predation recorded was due to this species. Probability of egg predation was significantly and negatively correlated with distance to the nearest yellow-legged gull sub-colony, although this relationship was no more significant after adjustment for sub-colony size. On the other hand, distance to the nearest Audouin´s gull sub-colony did not show any effect. Our results suggest that the impact of large gulls (at least yellow-legged gulls) upon smaller seabirds breeding in the area might be important, especially when they are breeding in small sub-colonies. Further studies are needed to analyse the general impact of large gulls upon the breeding populations of other colonial bird species in the area.

Artificial diets for the production of natural enemies (predators and parasitoids) of greenhouse pest insects

The aim of this contract was to finalise in vitro rearing on artificial diets of entomophagous insects useful to control insect pests mainly in greenhouses through an analytical and rational approach. The work focuses on the development and optimisation of artificial diets for one coccinellid (Harmonia axyridis), two heteropteran predators (Orius laevigatus, Dicyphus tamaninii), and a braconid parasitoid of aphids (Aphidius ervi). The definition of the artificial diets was based on biochemical analyses of their natural food (aphids) or substitution food for the predators (Ephestia kuehniella eggs). Reliable quality control parameters of the entomophages produced were used in order to adjust dietary composition and formulation of the different diets tested.

Composición en ácidos grasos de huevos y larvas de dentón (Dentex dentex L.) de hasta 40 días en condiciones de cultivo

Total lipid content and fatty acid (FA) composition of common dentex eggs spawned at different times and larvae reared under different culture conditions until 40 days post hatch (dph) were analysed in order to get a general pattern of lipid composition during larval development. Results were grouped according to the developmental stage of the larvae instead of age in dph. Saturated and monounsaturated fatty acids decreased along larval development, while polyunsaturated fatty acid (PUFA) content increased. The ratio of docosahexaenoic acid (DHA) / eicosapentaenoic acid (EPA) shifted from 4 – 5 in early developmental stages to lower than 1 after metamorphosis. Results suggest a subdivision of the larval development into two stages of opposite FA requirements.

Agapornis: relació entre fertilitat i neixements en els Agapornis lilianae i negrigenis

Treball de recerca realitzat per un alumne d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. A partir d’ous exemplars de dues espècies d’agapornis -nigrigenis i lilianae-, es pretén realitzar un estudi comparatiu d’ambdues, tant pel que fa a l’etologia com a la reproducció, als hàbits alimentaris, etc. La idea inicial parteix de la possibilitat d’intercanviar alguns ous de cada espècie per mirar d’esbrinar si els ocells reproductors s’adonen de tal canvi. La hipòtesi inicial del treball considera que els ocells els criaran de la mateixa forma que si es tractés dels seus propis pollets. Les conclusions, però, han anat més enllà de la formulació de la hipòtesi inicial, de tal manera que, al final, i en forma de diagrama, s’ha pogut parlar de l’eclosió o manca d’eclosió dels ous d’aquesta espècie, tot relacionant temes diversos que van des de la fertilitat a les diferents mides dels ous. A més, l’autor també ha pogut concloure que els Agapornis lilianae són capaços de criar ocells d’una altra espècie (en aquest cas d Agapornis roseicollis) amb tota normalitat.

La natura és sàvia: procés d'incubació i cria de la gallina Nana de Flor d'Atmeller

Treball de recerca realitzat per una alumna d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. L’autora del treball ha tingut la possibilitat d’estudiar de prop una comunitat de gallines d’una raça concreta: Gallina nana flor d’ametller. La seva curiositat l’ha conduït a portar a l'Escola uns ous fecundats deixant la resta de la posta amb la gallina. Així comença l’estudi que té com objectiu establir similituds i diferències entre la cria natural i l’artificial en una incubadora. Posteriorment, aquest treball s’ha completat amb la comparació d’uns exemplars concrets de pollets de la raça estudiada. S’arriba clarament al final del treball a unes conclusions molt concretes: resulta molt difícil igualar de forma artificial allò que a la natura sembla que es realitza amb tanta facilitat. Per això es conclou taxativament que 'la natura és sàvia’.