Indigenous parasitoids (Hym., Chalcidoidea) of Phyllocnistis citrella Stainton (Lep., Gracillariidae) in Jaguariúna, São Paulo State, Brazil: preliminary results

Abstract: The citrus leafminer, Phyllocnistis citrella Stainton, is native to Asia and was detected for the first time in Brazil in 1996. The objectives of this study were to conduct a survey of parasitoids attacking citrus leafminer in Jaguariúna, one of the citrus production regions of São Paulo State, Brazil, and to determine whether indigenous species were providing effective control of this pest species. The collections of new leaves were made weekly at citrus groves in Jaguariúna from October 1996 to October 1997. Of the six indigenous parasitoids which were found, Galeopsomyia fausta LaSalle was the most abundant parasitoid of P. citrella in this region, accounting for more than 90% of the specimens collected. Thus, this species is a serious candidate for biological control of the citrus leafminer in this region of Brazil. Other species collected were Horismenus sp., Cirrospilus 'sp. C', Elasmus sp., Eupelmus sp. and Conura (Ceratosmicra) sp. The mean percentage of parasitism was 39.28% (6.19−86.21%) in unsprayed orchards and 21.38% (1.33−56.63%) in orchards that were occasionally treated with fungicides, acaricides and insecticides Temik and Dipterex.     

Population dynamics and functional response of Citrostichus phyllocnistoides (Narayanan) (Hym., Eulophidae) on citrus leaf-miner, Phyllocnistis citrella Stainton (Lep., Phyllocnistidae) in Fuzhou region of south-east China

Abstract:  Population dynamics of the citrus leaf-miner (CLM) Phyllocnistis citrella Stainton, and its major parasitoid Citrostichus phyllocnistoides (Narayanan) were investigated from June to September 1994 at the teaching and research farm of the Fujian Agricultural and Forestry University (FAFU), south-east China. Based on the field investigation, the functional and numerical responses of C. phyllocnistoides were studied in laboratory experiments. During the survey period, four peaks of CLM and C. phyllocnistoides populations were observed in the growing stage of summer shoots and two peaks of CLM and C. phyllocnistoides populations, respectively, in the growing stage of fall shoots. C. phyllocnistoides is the most abundant parasitoid both in seasonal and spatial dynamics, and demonstrates a Holling type III functional response to CLM. Parasitism varied with the densities of both parasitoid and host. A 1 : 10 ratio was recorded to be an optimal proportion of C. phyllocnistoides to CLM.     

Seasonal dynamics, dispersion, sequential sampling plans and treatment thresholds for the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), in a mature lemon block in coastal New South Wales, Australia

Abstract  Studies of citrus leafminer in a coastal orchard in NSW, Australia indicated that an increase in abundance to about one mine per flush was followed during the midseason flush by a rapid increase in population that was related to an increase in the percentage of leaves infested within flushes and the number of mines per leaf. The fits of frequency distributions and Iwao's patchiness regression indicated that populations were highly contagious initially, and as the exponent k of the negative binomial distribution increased with increasing population density, the distribution approached random. Concurrently, the coefficient of variation of mines per flush (which was strongly related to the proportion of un-infested flushes) decreased to about unity as the proportion of un-infested flushes reached zero and fell further as the number of mines per flush increased. Both numerative and binomial sequential sampling plans were developed using a decision threshold based on 1.2 mines per flush. The binomial sampling plan was based on a closely fitting model of the functional relationship between mean density and proportion of infested flushes. Functional relationships using the parameters determined from Iwao's patchiness regression and Taylor's power law were equally satisfactory, and one based on the negative binomial model also fitted well, but the Poisson model did not. The three best fitting models indicated that a decision threshold of 1.2 mines per flush was equivalent to 50% of flushes infested. From a practical point of view, the transition from 25% infestation of flushes through 50% is so rapid that it may be prudent to take action when the 25% level is reached; otherwise, the 50% may be passed before the crop is checked again. For valuable nursery stock should infestation be detected in spring, it may be advisable to apply prophylactic treatment as the midseason flush starts.     

Impact de la pollution sur un écosystème méditerranéen cǒtier. II. Relations entre la composition spécifique des populations phytoplanctoniques et les taux de pigments et de nucléotides adényliques (ATP,ADP, AMP)

Influences of unsalted waters penetration, in the Gulf of Fos, are marked as much on the primary step structuration level as on the component cellular physiology one. At their outlet, the weak structuration and the considerable biomasses resulting from an intense eutrophication go with a strong mortality clearly shown as well as by ATP/chlorophyll ratio than these of ATP, ADP and AMP inside the adenylic nucleotides pool. The primary step acquires a larger maturity in the salt share of the south eastern area. Spectrum variations of the population specific cellular volumes in terms of population importance can in a certain measure explain the intracellular rate variations into biochemical components.     

Traces d’impacts de projectiles sur le gibier : résultats comparés des tirs expérimentaux à l’arc et au propulseur effectués au Cedarc (Treignes, Belgique) en 2003 et 2004

In 2003 and 2004, two series of projectile experiments were organized by P. Cattelain and ourselves at the CEDARC/Musée du Malgré-Tout (Treignes, Belgium). The experiments involved the use of two male ox calves and two female fallow deers as targets for bow and spearthrower shooting. Our main focus was a functional analysis of the antler projectile tips from the Upper Magdalenian layer of the Isturitz cave site (Pyrénées-Atlantiques, France). The study of the impact traces on the bones of the target animals was also included in the project; its results are presented here. The observation of these 127 traces led us to reconsider the nomenclature suggested by P. Morel, and to distinguish between three major traces: notches, punctures and perforations. Correlations appear between the nature of the trace and the shape of the bone (e.g., scapulae strongly associated to perforations), and the bone's mineral content: compared to adult long bones, immature long bones are much more easily perforated by projectile points, which usually remain firmly caught in them. However, our results do not show a clear distinction between the impact traces left by the bow and by the spearthrower.