Ecological specialization of the aphid Aphis gossypii Glover on cultivated host plants.

Many plant-feeding insect species considered to be polyphagous are in fact composed of genetically differentiated sympatric populations that use different hosts and between which gene flow still exists. We studied the population genetic structure of the cotton-melon aphid Aphis gossypii that is considered as one of the most polyphagous aphid species. We used eight microsatellites to analyse the genetic diversity of numerous samples of A.

Host-parasitoid association and diffuse coevolution: when to be a generalist?

In host-parasitoid communities, hosts are subjected to selective pressures from numerous parasitoid species, and parasitoids may attack several host species. The specificity of host resistance and parasitoid virulence is thus a key factor in host-parasitoid coevolution. A continuum of strategies exists, from strict specificity to a generalist strategy.

An implicit approach to model plant infestation by insect pests.

Various spatial approaches were developed to study the effect of spatial heterogeneities on population dynamics. We present in this paper a flux-based model to describe an aphid-parasitoid system in a closed and spatially structured environment, i.e.

Rapid visual estimates of thrips (Thysanoptera: Thripidae) densities on cucumber and rose crops.

Scouting techniques combining rapid counting methods must be developed to help growers with immediate decision making in integrated pest management programs. We evaluated a method for estimating densities of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), one of the most damaging insect pests of greenhouse cucumber, Cucumis sativus L., and rose, Rosa x hybrida crops in southeastern France.

Dispersal strategies of phytophagous insects at a local scale: adaptive potential of aphids in an agricultural environment.

Background: The spread of agriculture greatly modified the selective pressures exerted by plants on phytophagous insects, by providing these insects with a high-level resource, structured in time and space. The life history, behavioural and physiological traits of some insect species may have evolved in response to these changes, allowing them to crowd on crops and to become agricultural pests. Dispersal, which is one of these traits, is a key concept in evolutionary biology but has been over-simplified in most theoretical studies.