Controversy exists over ecological risks in classical biological control. We reviewed 10 projects with quantitative data on nontarget effects. Ten patterns emerged: (a) Relatives of the pest are most likely to be attacked; (b) host-specificity testing defines physiological host range, but not ecological range; (c) prediction of ecological consequences requires population data; (d) level of impact varied, often in relation to environmental conditions; (e) information on magnitude of nontarget impact is sparse; (f) attack on rare native species can accelerate their decline; (g) nontarget effects can be indirect; (h) agents disperse from agroecosystems; (i) whole assemblages of species can be perturbed; and (j) no evidence on adaptation is available in these cases. The review leads to six recommendations: Avoid using generalists or adventive species; expand host-specificity testing; incorporate more ecological information; consider ecological risk in target selection; prioritize agents; and pursue genetic data on adaptation. We conclude that retrospective analyses suggest clear ways to further increase future safety of biocontrol.

The potential of natural enemies to influence the rate of herbivore adaptation to resistance factors in plants is examined using conceptual and mathematical models. Results indicate that natural enemies could increase or decrease the rate of herbivore adaptation. The specific behavioral and physiological effects of a resistance factor on the herbivore, as well as the behavior of the natural enemy, and the population dynamics of the natural enemy/herbivore system are important in assessing the extent to which the natural enemies will affect the rate of herbivore adaptation to a resistance factor. Herbivore adaptation to partial resistance in a host‐plant is generally expected to be slower than adaptation to high levels of resistance, even in the presence of natural enemies, if genetic variance is not limiting. Résumé Influence des ennemis naturels sur le taux d'adaptation d'herbivores à des plantes‐hôtes résistantes Des modèles conceptuels et mathématiques ont servi à examiner l'influence du potentiel d'ennemis naturels sur le taux d'adaptation d'herbivores à des facteurs de résistance des plantes. Les résultats montrent que les ennemis naturels peuvent augmenter ou réduire le taux d'adaptation des herbivores. Les effets spécifiques (comportementaux et physiologiques) d'un facteur de résistance sur l'herbivore, aussi bien que le comportement de l'ennemi naturel et la dynamique de population du système ennemi naturel/herbivore permettent de déterminer le niveau de l'effet des ennemis naturels sur le taux d'adaptation de l'herbivore au facteur de résistance. Une adaptation de l'herbivore à une résistance partielle à une plante est généralement envisagée comme plus lente qu'une adaptation à des hauts niveaux de résistance, même en présence d'ennemis naturels, mais il peut y avoir des exceptions.

We document causes of death in free-ranging California Condors (Gymnogyps californianus) from the inception of the reintroduction program in 1992 through December 2009 to identify current and historic mortality factors that might interfere with establishment of self-sustaining populations in the wild. A total of 135 deaths occurred from October 1992 (the first post-release death) through December 2009, from a maximum population-at-risk of 352 birds, for a cumulative crude mortality rate of 38%. A definitive cause of death was determined for 76 of the 98 submitted cases, 70% (53/76) of which were attributed to anthropogenic causes. Trash ingestion was the most important mortality factor in nestlings (proportional mortality rate [PMR] 73%; 8/11), while lead toxicosis was the most important factor in juveniles (PMR 26%; 13/50) and adults (PMR 67%; 10/15). These results demonstrate that the leading causes of death at all California Condor release sites are anthropogenic. The mortality factors thought to be important in the decline of the historic California Condor population, particularly lead poisoning, remain the most important documented mortality factors today. Without effective mitigation, these factors can be expected to have the same effects on the sustainability of the wild populations as they have in the past.

No abstract

Lead poisoning is a primary factor impeding the survival and recovery of the critically endangered California Condor (Gymnogyps californianus). However, the frequency and magnitude of lead exposure in condors is not well-known in part because most blood lead monitoring occurs biannually, and biannual blood samples capture only ∼10% of a bird’s annual exposure history. We investigated the use of growing feathers from free-flying condors in California to establish a bird’s lead exposure history. We show that lead concentration and stable lead isotopic composition analyses of sequential feather sections and concurrently collected blood samples provided a comprehensive history of lead exposure over the 2−4 month period of feather growth. Feather analyses identified exposure events not evident from blood monitoring efforts, and by fitting an empirically derived timeline to actively growing feathers, we were able to estimate the time frame for specific lead exposure events. Our results demonstrate the utility of using sequentially sampled feathers to reconstruct lead exposure history. Since exposure risk in individuals is one determinant of population health, our findings should increase the understanding of population-level effects from lead poisoning in condors; this information may also be helpful for other avian species potentially impacted by lead poisoning.