Ángel Hernández

Internal dispersal of seed-inhabiting insects by vertebrate frugivores: a review and prospects.

The finding that some seed-inhabiting insects can survive passage through the entire digestive tract of seed-dispersing vertebrates is relatively recent, but evidence suggests that it does occur. Here, I document this phenomenon, discuss its qualitative and quantitative dimensions, and offer suggestions for further research. The few documented cases that I review include plant species belonging to different families, with varied fleshy fruit types, number of seeds per fruit and seed size. The vertebrate frugivores involved include passerines that feed on relatively small fruits, and galliforms, and perissodactyls and primates that feed on larger fruits. The seed-inhabiting insects involved are the larvae of seed-infesting wasps, parasitoid wasps and seed-infesting beetles. The phenomenon has been verified in open, rural ecosystems in North America and Southern Europe, and in tropical and subtropical forests in South America. These varied scenarios suggest that the qualitative dimension of the phenomenon is considerably greater than known thus far. A simple method for detecting new events is proposed. However, research must also focus on the identity and biology of seed-feeding insects of wild fleshy fruits and their parasitoids. High survival rates of seed-inhabiting insects after vertebrate gut passage are predominant. This phenomenon generally appears to favor insect dispersal.

Summer-autumn feeding ecology of Pied Flycatchers Ficedula hypolueca and Spotted Flycatchers Muscicapa striata: the importance of frugivory in a stopover area in north-west Iberia.

North-west Iberia is a crucial stopover region for European populations of Pied Flycatchers Ficedula hypoleuca and Spotted Flycatchers Muscicapa striata during their summer-autumn migration. Both species are almost completely insectivorous during breeding in Europe and wintering in sub-Saharan Africa, but are known to consume fleshy fruits during summer-autumn migration, though no detailed investigations have been carried out over long periods of time. In this study, the summer-autumn feeding ecology of Pied and Spotted Flycatchers in a stopover area in north-west Spain, with a landscape of hedgerows and irrigated meadows, was studied for five consecutive years (2002–2006). In general, the passage of both flycatcher species was noticeable from mid-August to the end of September, with a peak in the first ten days of September. The two flycatcher species consumed fruits throughout the stopover period in all years, with constant intensity of frugivory in time, though the importance of fruits was almost three times greater in the diet of Pied Flycatchers ( c . 30% of feeding acts) than in that of Spotted Flycatchers ( c . 10% of feeding acts). Both species preferred Dogwood Cornus sanguinea fruits, but also ate Elder Sambucus nigra berries and Bramble Rubus spp. drupelets. The high level of selection of Dogwood fruits was probably linked to their high lipid content, an essential nutrient for fattening in long-distance migrant passerines. Hedgerows and wood edges in north-west Iberia are rich in fleshy fruits but threatened by intensive farming. Their conservation and restoration are proposed because they seem to be high-quality stopover habitats for partially frugivorous passerines during summer-autumn migration.

Frugivorous birds dispersing braconid parasitoids via endozoochory

Adult braconid wasps (Bracon sp.) emerged from the droppings of frugivorous birds (Turdus blackbirds and thrushes) collected in a rural environment in southern Europe. It was thus demonstrated for the first time that an insect parasitoid of a fruit‐infesting insect (lepidopteran tortricid) can survive bird ingestion and gut passage inside a seed (privet Ligustrum vulgare), constituting a case of an evolutionary tetrad.

Quantitative parameters and ecological implications of a specialized tritrophic interaction involving a seed-feeding tortricid, Pseudargyrotoza conwagana, a braconid parasitoid, Bracon otiosus, and the wild privet, Ligustrum vulgare

Abstract Little is known about tritrophic interactions involving seed-feeding insects, parasitoid wasps, and wild fleshy fruits. Here, we examine relationships between Pseudargyrotoza conwagana (F.) (Lepidoptera: Tortricidae), Bracon otiosus Marshall (Hymenoptera: Braconidae), and the wild privet, Ligustrum vulgare L. (Lamiales: Oleaceae), after collecting fruits in a hedgerow habitat in northwest Spain and rearing insects indoors. No other insect species was detected in this trophic system. Each fruit contained one to four seeds, each infested fruit contained only one seed-feeding tortricid caterpillar, and each parasitized caterpillar was affected by a single braconid individual, i.e., B. otiosus was a solitary parasitoid. Almost half of the wild privet shrubs were infested by P. conwagana , and infestation ranged from 2 to 32% of fruits per infested shrub. The general effect of P.conwagana on wild privet dispersal can be considered low, as the overall rate of seed infestation was low (6% of seeds). The infestation rate was higher in wild privet shrubs with a larger number of seeds per fruit, and tortricid caterpillars that left the fruits successfully ate >80% of seeds. In total, the parasitism rate was moderate (25% of caterpillars), but varied considerably (0‒75%) among shrubs where P. conwagana infestation was detected. Parasitism only occurred in shrubs showing high infestation rates (19‒32% infested fruits), i.e., with high host densities; however, the parasitism rate was density-independent in these shrubs. The wild privets benefited from the action of B. otiosus in two ways: the tortricid caterpillar population was partly eliminated, and the caterpillars were prevented from eating more than one seed per fruit. The B. otiosus sex ratio was very balanced (1 male to 1.18 females). Winter diapause and protandry were prevalent in B. otiosus .

Diet of Eurasian Sparrowhawks in a Northwest Iberian Hedgerow Habitat throughout the Year

Abstract Little is known about Eurasian Sparrowhawk Accipiter nisus feeding habits outside the breeding season in its wide geographical range. The present study concerns the autumn-winter and spring-summer diet of this raptor species in Northwest Spain in a hedgerow habitat. A total of 23 avian prey species were recorded, only six of which occurred in both periods of the year. However, Eurasian Sparrowhawks fed mainly on medium-sized birds that often forage on the ground at some distance from shrubs and trees, mostly the Song Thrush Turdus philomelos and the Common Blackbird Turdus merula, both species together accounting for approximately half of the prey in any season of the year. The contribution of larger birds, i.e., pigeons, was considerable in terms of ingested biomass. In spring-summer, the mean body weight of avian prey was over 15 g less than in autumn-winter.