Long-term datasets in biodiversity research and monitoring: assessing change in ecological communities through time.

The growing need for baseline data against which efforts to reduce the rate of biodiversity loss can be judged highlights the importance of long-term datasets, some of which are as old as ecology itself. We review methods of evaluating change in biodiversity at the community level using these datasets, and contrast whole-community approaches with those that combine information from different species and habitats. As all communities experience temporal turnover, one of the biggest challenges is distinguishing change that can be attributed to external factors, such as anthropogenic activities, from underlying natural change. We also discuss methodological issues, such as false alerts and modifications in design, of which users of these data sets need to be aware.

The effect of parasitism on the population dynamics of the macadamia nutborer Gymnandrosoma aurantianum (Lepidoptera: Tortricidae)

Biological control on crop infesting insects represent an useful method in modern agriculture. A search for parasitoids of the macadamia nutborer was carried out during a three year study, and their effect on the population fluctuation of the borer was determined. An egg parasitoid belonging to the family Trichogrammatidae and four larval parasitoids, Microgastrine I, Microgastrine II, Ascogaster sp. (Hymeoptera: Braconidae) and Pristomerus sp. (Hymeoptera: Ichneumonidae) were recovered. Parasitism percentage by Microgastrine I was 15% in 1991, 16% in 1992 and 4% in 1993; Microgastrine II was not collected in 1991, but accounted for a 4.3% of parasitism in 1992 and 3.7% in 1993; Ascogaster sp. was registered since 1992 with 3% parasitism (29% in 1993). We found an inverse relationship between total parasitism and the mean of damaged nuts. Parasitoids play an important role in the reduction of the G. aurantianum population. Rev. Biol. Trop. 57 (4): 1245-1252. Epub 2009 December 01.

Durante tres años se realizó una búsqueda de los enemigos naturales del barrenador de la nuez de macadamia y se determinó el efecto sobre su población. Se registró un parasitoide de huevo perteneciente a la familia Trichogrammatidae y cuatro parasitoides de larva, Microgastrine I, Microgastrine II, y Ascogaster sp. (Hym: Braconidae) y Pristomerus (Hym: Ichneumonidae). El porcentaje de parasitismo por Microgastrine I fue del 15% en 1991, 16% en 1992 y 4% en 1993; Microgastrine II no se registró en 1991, pero alcanzó un 4.3% de parasitismo en 1992 y un 3.7% en 1993; Ascogaster sp. se registró a partir de 1992 con un 3% de parasitismo y con un 29% en 1993. Se encontró una relación inversa entre el parasitismo total y el promedio de nueces dañadas. Los resultados indican que los parasitoides juegan un papel importante en la disminución de la población de G. aurantianum.

The effect of parasitism on the population dynamics of the macadamia nutborer Gymnandrosoma aurantianum (Lepidoptera: Tortricidae).

Biological control on crop infesting insects represent an useful method in modem agriculture. A search for parasitoids of the macadamia nutborer was carried out during a three year study, and their effect on the population fluctuation of the borer was determined. An egg parasitoid belonging to the family Trichogrammatidae and four larval parasitoids, Microgastrine I, Microgastrine II, Ascogaster sp. (Hymeoptera: Braconidae) and Pristomerus sp. (Hymeoptera: Ichneumonidae) were recovered. Parasitism percentage by Microgastrine I was 15% in 1991, 16% in 1992 and 4% in 1993; Microgastrine II was not collected in 1991, but accounted for a 4.3% of parasitism in 1992 and 3.7% in 1993; Ascogaster sp. was registered since 1992 with 3% parasitism (29% in 1993). We found an inverse relationship between total parasitism and the mean of damaged nuts. Parasitoids play an important role in the reduction of the G. aurantianum population.

Scale-specific correlations between habitat heterogeneity and soil fauna diversity along a landscape structure gradient.

Habitat heterogeneity contributes to the maintenance of diversity, but the extent that landscape-scale rather than local-scale heterogeneity influences the diversity of soil invertebrates-species with small range sizes-is less clear. Using a Scottish habitat heterogeneity gradient we correlated Collembola and lumbricid worm species richness and abundance with different elements (forest cover, habitat richness and patchiness) and qualities (plant species richness, soil variables) of habitat heterogeneity, at landscape (1 km(2)) and local (up to 200 m(2)) scales. Soil fauna assemblages showed considerable turnover in species composition along this habitat heterogeneity gradient. Soil fauna species richness and turnover was greatest in landscapes that were a mosaic of habitats. Soil fauna diversity was hump-shaped along a gradient of forest cover, peaking where there was a mixture of forest and open habitats in the landscape. Landscape-scale habitat richness was positively correlated with lumbricid diversity, while Collembola and lumbricid abundances were negatively and positively related to landscape spatial patchiness. Furthermore, soil fauna diversity was positively correlated with plant diversity, which in turn peaked in the sites that were a mosaic of forest and open habitat patches. There was less evidence that local-scale habitat variables (habitat richness, tree cover, plant species richness, litter cover, soil pH, depth of organic horizon) affected soil fauna diversity: Collembola diversity was independent of all these measures, while lumbricid diversity positively and negatively correlated with vascular plant species richness and tree canopy density. Landscape-scale habitat heterogeneity affects soil diversity regardless of taxon, while the influence of habitat heterogeneity at local scales is dependent on taxon identity, and hence ecological traits, e.g. body size. Landscape-scale habitat heterogeneity by providing different niches and refuges, together with passive dispersal and population patch dynamics, positively contributes to soil faunal diversity.

Within-tree distribution of Ecdytolopha torticornis (Lepidoptera: Tortricidae) oviposition on macadamia nuts

Vertical distribution of eggs of the macadamia nutborer Ecdytolopha torticornis Meyrick (Lepidoptera: Tortricidae) and its preference of oviposition sites within and between macadamia cultivars were studied in Turrialba, Cartago, Costa Rica, in 1992 (N = 6,939). E. torticornis eggs were found throughout the foliar parts of the tree, but fewer eggs were laid in the crown top than in the mid or lower crown. Differences in the horizontal distribution of the eggs were not significant, albeit more eggs were found in the outer positions. The numbers of eggs found within the crowns of different clones were similar, implying that the nutborer has no preference for a particular cultivar.