The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons.

The community of nematodes (Nematoda: Secernentea) in groves of North East Algeria, has been the subject of regular observations of September 2011 to May 2012. Sampling and extraction of nematodes by the buckets technique are conducted following the method of Baermann. The sampling groves are composed by olive trees (Olea europea: Oleaceae) from four varieties: Chemlal, Sigoise, Frontoï and Sévillane. We identified a total of 531 individuals. The systematic inventory revealed 14 genus of Nematoda, belonging to 10 families and 3 orders. The Tylenchida and Dorylaimida are the best represented orders. They represent 92.85% of the total community of all identified nematodes, while Aphelenchida represent only 7.15%. The genus Pratylenchus records alone 54.75% on the Sévillane variety and 33.02% on the Frantoi variety. The most represented genus on Sigoise and Chemlal varieties is Meloidogyne with respectively 43.24% and 30.43%. Grove of Sévillane variety hosts the highest abundance of nematodes with 57.44%; against only 19.96%, 13.94% and 8.66%, respectively, for the varieties Frantoi, Sigoise and Chemlal. Depending on the seasons, nematodes are more abundant in autumn (88.52%) than in winter (8.66%) and the spring (2.82%). Pratylenchus and Meloidogyne are noted with large numbers, especially in winter.

Le suivi démo-écologique de la cochenille Pollinia pollini est réalisée dans une oliveraie de la région semi-aride d’Arris (Nord-est Algérie) durant une période d’une année, allant de janvier à décembre 2015. L’étude du mode d’infestation de l’olivier Olea eurpaea par la cochenille est basée sur des dénombrements des différents stades de développement de l’espèce sur les rameaux. Ces dénombrements sont réalisés suivant les orientations de l’arbre (Nord, Est, Sud, Ouest et Centre) et suivant le mode d’installation de la cochenille sur les rameaux (à la surface des rameaux, aux aisselles des rameaux et des feuilles ou à l’intérieur du bois). Ce travail montre que P. pollini évolue en une seule génération annuelle. La parution des larves du premier stade commence à la troisième décade de mars et se poursuit jusqu’à la mi-août. Les larves du deuxième stade apparaissent à la troisième décade d’avril et enregistrent leur pic en juillet. Les femelles adultes, qui sont présentes le long de la période d’étude, enregistrent leurs effectifs maximaux en octobre et en novembre. L’étude de l’abondance globale de P. pollini en fonction des orientations montre que l’espèce s’installe préférentiellement dans les parties Nord, Est et Ouest de l’arbre, avec des proportions relativement proches allant de 20 % à 22 %. Le suivi de l’emplacement de P. pollini sur les rameaux de l’olivier montre que la cochenille s’installe dans trois emplacements différents. Elle préfère s’installer aux aisselles des rameaux et des feuilles (43,23 %), à la surface des rameaux (29,15 %) et à l’intérieur du bois (27,62 %).

Researches carried out in the past years allowed to list an entomofauna that lives on the apricot orchards, Prunus armeniaca L. (Rosales Rosaceae), in Ouled Si Slimane (Batna Department, Algeria). The investigated period was from October 2014 until May 2015. The sampling techniques used were: hunting in sight, barber pots, colorful traps, entomological umbrella and the filleting net. We have identified a total of 125 species divided into 9 orders and 54 families in which Coleoptera and Hymenoptera were quantitatively represented. The phytophagous were the most present. Its Shannon Value exceeds 4.5 Bits and indicates a Specific Richness of the insects and diversification of ecological niches in this kind of fauna.

The composition of the diet of the barbel (Luciobarbus callensis) was studied in the K'sob reservoir near the town of M'Sila (Algeria). The capture of the barbels was carried out between September 2010 and August 2011.The diet was studied from 379 specimens collected by trammel net. During the study period, it was noted that the food spectrum essentially consisted of Chironomids, Ephemeroptera and Copepods, which are abundant in the environment. The barbel of the K'sob reservoir has a seasonal food pattern influenced by climatic and ecological conditions and by its reproductive cycle. The diet of L. callensis in the study area is omnivorous, with a zoo-benthophage tendency.

This study investigated insect diversity of olive (Olea europaea Linnaeus (Oleaceae)) groves grown in arid and semiarid climates in northeastern Algeria. Using several sampling techniques, a total of 1326 insect specimens were collected and identified into 151 species, 124 genera, 65 families, and 10 orders. Hymenoptera and Coleoptera were quantitatively the most abundant, whereas the dominant functional feeding groups were phytophages then predators. The entomofauna included several olive pests such as Bactrocera oleae (Rossi) (Diptera: Tephritidae), Parlatoria oleae (Colvée) (Hemiptera: Diaspididae), Euphyllura olivina (Costa) (Hemiptera: Liviidae), and Liothrips oleae Costa (Thysanoptera: Phlaeothripidae). Although insect diversity parameters recorded for both observed and expected species richness were higher in olive groves grown under semiarid compared with arid climate, the completeness rate of species richness obtained using the nonparametric incidence estimators was higher in arid olive groves. Generalised linear models showed that the number of individuals and species richness varied significantly between climates (P < 0.01), whereas the variation of the rest of diversity parameters was not significant. Diversity traits of insect assemblage of each climatic region were positively correlated. Besides, the Mantel permutation test revealed similar patterns (r = 0.91, P < 0.0001) between correlation matrices of the two climates. When increasing the number of samples, species richness extrapolation revealed that diversity is expected to increase by 130% in olive groves grown under arid climate and 93% in semiarid climate. These increases are related to continuous appearance of rare and scarce insects as demonstrated by species rarefaction curves. Even with high evenness values of insect communities, similarity was low between climate indicating the rarity and scarcity of populations.