A sequential sampling program was designed for Coccinella septempunctata L. adults in wheat fields, based on a rapid visual counting method. This program takes into account the spatial heterogeneity of coccinellids and the efficiency of the counting method. The relationship between the mean and variance of the numbers sampled was described by Taylor’s power law.

The reliability of three methods for sampling aphidophagous coccinellids and syrphids in a winter wheat field was compared.

In the first method, an observer recorded predators seen during 2 min per 25-m2 sub-plot. In the second, two observers worked successively through each plot, scanning the full height of wheat plants and collecting predators. This method enables calculation of predator density using De Lury’s technique. The third method consisted of collecting wheat plants from each sub-plot for examination in the laboratory.

The first method may be used for appraising populations of adult coccinellids on a large scale. The detailed searching method is appropriate for studies of the population dynamics of adult and fourth-instar coccinellids. The plant sampling method is the most accurate for assesssing densities of syrphid larvae and pupae.

The developmental rate of Frankliniella occidentalis (Pergande) was determined on cucumber Cucumis sativus cv. Sandra over a range of constant temperatures. The lower developmental threshold (LDT) and the sum of effective temperatures (SET) for the pre-imaginal development were 10.7°C and 231.1°C, respectively. The rate of population increase was assessed as the sum of effective temperatures above the lower developmental threshold by monitoring the numbers of thrips on individual leaves of cucumber under commercial greenhouse conditions. Population growth was characterized by an early stochastic phase, corresponding to pre-imaginal development of the first generation, and followed by an exponential phase starting with the second generation, the rate of which did not vary between plants. Throughout the exponential phase, the rate of population growth increased with time/age of plant. As significant damage to cucumber may occur during the exponential phase of population increase, the sum of effective temperatures of 231°C can be used to predict when damage is likely to start to occur.

Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach–potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.

Trois espèces d'Hydropsychidae ont été capturées dans la basse Nivelle à l'état de larves ou d'adultes : Cheumatopsyche lepida, Hydropsyche pellucidula et Hydropsyche siltalai. Une espèce de "profonds", Hydropsyche ornatula, n'a été obtenue qu'à l'état adulte.

Les cycles de développement de ces espèces sont complexes et variables. Une génération estivale facultative, liée aux conditions climatiques, semble se superposer au cycle classique, en particulier pour H. pellucidula.

La production larvaire est de 8,3 à 10,8 g/m2/an (poids humide) ; le taux de renouvellement (P/$\bar{B}$$\mathrm{See\; PDF}$ ) varie de 2,7 à 6,6 selon les espèces et les méthodes de calcul.

L'étude des imagos et des larves de Simuliidae a été effectuée au cours de trois années dans un cours d'eau de l'ouest des Pyrénées.

La température élevée, les herbiers à renoncules, une certaine pollution organique, sont les facteurs favorables au développement des Wilhelmia, surtout de W. lineata, associée à W. equina et W. mediterranea.

Les cycles de développement sont synchrones, avec quatre générations par an. La génération d'été est la plus forte, les autres sont réduites par les crues et les parasites.

La taille des adultes suit les fluctuations thermiques.

Les stades larvaires présentent des différences dans leur microrépartition. La production larvaire est de l'ordre de 0,6 g/cm3/an sur les renoncules et de 0,9 g/m2/an sur les cailloux, avec des rapports [MATH] annuels entre 6,6 et 7,6.