during a two-year (2004-2005) survey of alfalfa aphids and their natural enemies in isfahan, a total of four aphid species and 58 species of their natural enemies comprised of 45 predatory species, 11 parasitoid species and two species of parasitic mites were collected and identified. moreover, five hyperparasitoid species were collected. on each sampling date, six 20-sweep samples were taken u...

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...

Predators affect herbivores directly and indirectly, by consumptive and nonconsumptive effects, and the combined influence of multiple predators is shaped by interactions among predators. I documented the individual and combined effects of birds (chickadees, nuthatches, warblers) and ants (Formica podzolica) on arthropods residing in pine (Pinus ponderosa) canopies in a factorial field experime...

In conservation biological control, we seek to make agricultural systems more hospitable to natural enemies, in an attempt to increase enemy abundance and diversity. However, it is unclear whether the effectiveness of biological control actually increases with growing natural enemy diversity, in communities including many species of generalist predators. Studies have shown that suppression of h...

Host plant defenses are known to cascade up food chains to influence herbivores and their natural enemies, but how herbivore and predator traits and identity mediate such tri-trophic dynamics is largely unknown. We assessed the influence of plant defense on aphid and coccinellid performance in laboratory trials with low- vs. high-glucosinolate varieties of Brassica napus, a dietary specialist (...

Insect natural enemies (predators and parasitoids) provide important ecosystem services by suppressing populations of insect pests in many agricultural crops. However, the role of natural enemies against cereal aphids in Michigan winter wheat (Triticum aestivum L.) is largely unknown. The objectives of this research were to characterize the natural enemy community in wheat fields and evaluate t...

The drive towards a more sustainable and integrated approach to pest management has engendered a renewed interest in conservation biological control, the role of natural enemy communities and their interactions with prey. Monoclonal antibodies have provided significant advances in enhancing our knowledge of trophic interactions and can be employed to help quantify predation on target species. T...

Some experiments indicate the ability of coccinellids to significantly suppress aphid abundance. Exclusion of predators by caging aphid-infested plants has repeatedly resulted in higher aphid populations and greater aphid population growth rates. However, aphidophagous coccinellids have never proved effective in controlling aphid populations in the field. To resolve this apparent contradiction,...