Summary This work characterises the changes in composition of the weed flora commonly associated with certain south‐eastern Algerian crops over a 20‐year period. Vegetation sampling was carried out between 1990 and 2010 in three 1 ha date palm plantations that do not have understory crops, six 400 m² glasshouses used for market gardening and three 30 ha cereal centre‐pivot irrigation plots. In total, 162 species belonging to 40 families were recorded. As in many other agroecosystems around the world, the dominant families were Poaceae, Asteraceae, Brassicaceae and Amaranthaceae representing 45.1% of the species identified. The weed communities were characterised by a set of species from various origins: species with biregional, triregional and multiregional origins, and Saharo‐Arabian and Mediterranean species were particularly well represented. Overall, the most common weed species were as follows: Chenopodium murale, Lolium multiflorum, Melilotus indicus, Lysimachia arvensis, Sonchus oleraceus, Setaria verticillata, Polypogon monspeliensis and Erigeron canadensis, all of which are therophytes. The weed flora differed among the three sampled agroecosystems, which is to be expected, as their respective management sequences are quite different. Weed monitoring over the 20 years showed that weed composition changed over time, particularly in the palm plantations and the cereal plots. For a better understanding of the drivers of weed composition and changes over time and better weed management, studying weed provenance (crop seed purchase and organic fertilisation) as well as agricultural practices is necessary.

She conducts research on protection of ecosystems in arid zones and seed ecophysiology of native plants, and is interested in their conservation and their application in ecological restoration programs.

This paper studies the effect of the plant support on the biological activity of Ceratitis capitata, as well as the estimated infestation rate of certain fruit trees (orange, mandarin, fig, apricot and pomegranate) in two regions of extreme south-eastern Algeria. The results show that the fruits most bitten by the Mediterranean fly are pomegranates with a number varying between 2 and 40 bites/fruit (9.2 ± 0.5 bites/fruit), while figs are the least bitten with a number varying between 1 and 4 bites/fruit (1.7 ± 0.1 bites/fruit). In terms of infestation, apricot (Rd = 93.3%) and pomegranate (Rd = 88.6%) are the trees most attacked by Ceratitis capitata, while orange is the least attacked (Rd = 42%). The study of some bio-ecological parameters of this bio-aggressor shows that the pupal period varies according to the type of host plant, between 6.9 ± 1.7 days (apricot) and 13.0 ± 1.8 days (mandarin), with zero emergence for orange tree. Pupae size varies very little between host plants, with 4.2 ± 0.2 mm for languor and 1.9 ± 0.0 mm for large diameter. The emergence rate also varies between crops (p = 0.038) from 33.8 ± 14.7% (apricot) to 63.4 ± 20.5% (mandarin). The same is true for adult longevity. The sex-ratio of C. capitata is higher for females on all host plants. Thus, this study shows that the infestation of C. capitata depends on the host plants, the pupal stage duration, the emergence rate and the longevity of adults (very long during the winter and decreased during the summer period)

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