Egg parasitoids of the genus Trichogramma are the most widely used natural enemy for biological pest control in the world. Their use is restricted to lepidopterous pest species. Due to relatively cheap mass rearing systems employing factitious host species, Trichogramma are usually applied for inundative biological control: repeated releases of high numbers of parasitoids aiming at a direct con...

population dynamics of three main alfalfa aphids, namely: pea aphid, acyrthosiphon pisum (harris), spotted alfalfa aphid, therioaphis trifolii forma maculata (buckton), black alfalfa aphid, aphis craccivora koch, and their most abundant predators and parasitoids in three sites and in two subsequent years in isfahan, iran, were investigated. the results revealed that frequency and temporal occur...

Theoretical and empirical studies have shown that enemy-victim interactions in spatially homogenous environments can exhibit diverging oscillations which result in the extinction of one or both species. For enemy-victim models with overlapping generations, we investigate the dynamical implications of spatial heterogeneity created by enemy-free sinks or victimless sinks. An enemy-free sink is a ...

The enemy release hypothesis is frequently invoked to explain invasion by nonnative species, but studies focusing on the influence of enemies on natural plant range expansion due to climate change remain scarce. We combined multiple approaches to study the influence of plant-enemy interactions on the upper elevational range limit of sugar maple (Acer saccharum) in southeastern Québec, Canada, w...

Recent work defines coevolution between plants and herbivores as pairwise when the pattern of selection on resistance traits and the response to selection are both independent of the presence or absence of other herbivores. In addition, for a pairwise response to selection, resistance to a focal herbivore must have the same genetic basis in the presence and absence of other herbivores. None of ...

A field study was conducted over 2 yr to determine the effects of transgenic sweet corn containing a gene from the bacterium Bacillus thuringiensis (Bt) on the diversity and abundance of nontarget arthropods. The Bt hybrid (expressing Cry1Ab endotoxin for lepidopteran control) was compared with near-isogenic non-Bt and Bt hybrids treated with a foliar insecticide and with a near-isogenic non-Bt...