Fluctuations of aphid populations on grapefruit (Citrus x paradisi Macfad.)

Very few studies were carried out to investigate the aphids attacking grapefruit. These pests cause considerable damages on citrus trees and other crops. This paper reports on the fluctuations of aphids on grapefruit in the region of Skikda (Algeria). From January 2012 to December 2013, monthly surveys were performed to measure the abundance of aphids recorded on 16 leaves of grapefruit. Through this study, five aphid species were identified, among them Aphis spiraecola Patch, 1914 was the most numerous. Besides, we noticed that the populations of aphids reached high levels many times within the year. However, the most important densities were recorded in spring and autumn.</p

Biodiversity of Culicidae (Insecta: Diptera) in the Region of Khenchela (Northeast Algeria)

Mosquitoes are considered as vectors of serious human diseases. The prevention of parasitic and arboviral vector-borne diseases is based mostly on vector control strategies. This control cannot be effective unless a strong knowledge of mosquito biology and distribution in the working area. In this context, and in order to improve the knowledge on the specific diversity of the culicids fauna in the region of Khenchela (northeast of Algeria), an inventory of mosquitoes was carried out for the first time in this region. Larval collection was conducted in various types of habitats through continuous monitoring of seven sites from May 2020 to September 2021.Systematic study revealed the presence of 10 species belonging to 5 genera; including Culexpipiens (Linneaus, 1758), Culexterritans (Walker, 1856), Culextheileri (Theobald, 1903), Culexmodestus (Ficalbi, 1890), Culisetalongiareolata (Macquart, 1838), Culisetaannulata (Schrank, 1776), Aedesgeniculatus (Olivier, 1791), Aedesvexans (Meigen, 1830), Orthopodomyiapulcripalpis (Rondani, 1872) and Uranotaeniaunguiculata (Edwards, 1913). The species Cx. pipiens was the most abundant (44.26 %) followed by Cs. longiareolata (39.57 %). The variation of diversity in the different sites depends on the type of breeding habitat. Our findings provide very important information on biodiversity, distribution and the relationship between species abundance and ecological factors. Therefore, the results can be very useful for the design and implementation of effective control programs

Core proteome mediated subtractive approach for the identification of potential therapeutic drug target against the honeybee pathogen Paenibacillus larvae

Background & Objectives American foulbrood (AFB), caused by the highly virulent, spore-forming bacterium Paenibacillus larvae, poses a significant threat to honey bee brood. The widespread use of antibiotics not only fails to effectively combat the disease but also raises concerns regarding honey safety. The current computational study was attempted to identify a novel therapeutic drug target against P. larvae, a causative agent of American foulbrood disease in honey bee. Methods We investigated effective novel drug targets through a comprehensive in silico pan-proteome and hierarchal subtractive sequence analysis. In total, 14 strains of P. larvae genomes were used to identify core genes. Subsequently, the core proteome was systematically narrowed down to a single protein predicted as the potential drug target. Alphafold software was then employed to predict the 3D structure of the potential drug target. Structural docking was carried out between a library of phytochemicals derived from traditional Chinese flora (n > 36,000) and the potential receptor using Autodock tool 1.5.6. Finally, molecular dynamics (MD) simulation study was conducted using GROMACS to assess the stability of the best-docked ligand. Results Proteome mining led to the identification of Ketoacyl-ACP synthase III as a highly promising therapeutic target, making it a prime candidate for inhibitor screening. The subsequent virtual screening and MD simulation analyses further affirmed the selection of ZINC95910054 as a potent inhibitor, with the lowest binding energy. This finding presents significant promise in the battle against P. larvae. Conclusions Computer aided drug design provides a novel approach for managing American foulbrood in honey bee populations, potentially mitigating its detrimental effects on both bee colonies and the honey industry

Razmerje med pojavljanjem jabolčne uši Aphis spiraecola Patch, 1914 (Hemiptera: Aphididae) in mineralno sestavo listov citrusov

Spring and autumn flushes are generally the most infested periods by citrus aphids. Nevertheless, the role of citrus foliar minerals on aphids is not clear. Thus, this paper aims to study the correlation between certain minerals and the infestation degree of citrus varieties by Aphis spiraecola. Aphid counting was carried out on 12 leaves for each of the six species retained (clementine, lemon, grapefruit and three varieties of mandarin), during autumn (October 2014) and spring (April 2015) flushes. In addition, mineral contents of the leaves in P, K, Na, Ca and Li were measured for the same periods. The results showed that the infestation levels of the studied varieties were higher in the spring flush than in the autumn one. Moreover, analyzes of young leaves showed an important intraspecific (mandarin varieties) and interspecific differences in the mineral composition between the examined citrus trees. The study of the relationship between infestation levels by A. spiraecola and mineral content of the six examined species showed no significant correlation, suggesting a marginal role of the five analyzed minerals in the relation citrus – A. spiraecola. Spomladanski in jesenski viški rasti citrusov so navadno obdobja njihove največje okužbe z listnimi ušmi, vendar je znano zelo malo o pomenu mineralne sestave listov na njihovo pojavljanje. Namen prispevka je bil preučiti korelacijo med nekaterimi minerali v listih različnih citrusov in stopnjo okužbe z listno ušjo Aphis spiraecola. Štetje listnih uši je bilo izvedeno na 12 listih vsake od preučevanih vrst (klementine, limone, grenivke in treh sort mandarine), v jesenski (oktober 2014) in spomladanski (april 2015) rasti. Dodatno so bile v istem obdobju v listih izmerjene vsebnosti P, K, Na, Ca in Li. Rezultati so pokazali, da je bila stopnja okužbe pri vseh sadnih vrstah večja v obdobju spomladanske kot jesenske rasti. Analize mladih listov so še pokazale pomembne znotrajvrstne razlike (med sortami mandarin) in medvrstne razlike v mineralni sestavi pregledanih citrusov. Raziskava odvisnosti med velikostjo okužbe z vrsto A. spiraecola in mineralno sestavo analiziranih vrst citrusov ni pokazala značilne korelacije, kar kaže na marginalno vlogo petih analiziranih mineralov v razmerju citrusov in preučevane listne uši

IN VITRO SCREENING OF INSECTICIDAL EFFECT OF PLANT AQUEOUS EXTRACTS ON THE COWPEA APHID APHIS CRACCIVORA

The research of new control methods that have low negative effects represent analternative aiming to limit disadvantages of chemical control of pests. This studyaimed to test the effect of 11 aqueous plant extracts belonging to four species(Santolina africana, Juniperus thurifera, Artemisia herba-alba and Pituranthosscoparius), on the larvae of the aphid Aphis craccivora installed on the leaves ofRobinia pseudoacacia under laboratory conditions. The insecticidal effect ofaqueous extracts on the mortality of aphids was evaluated by the introduction ofacacia leaflet into an extract and infestation of them by 10 larvae of the aphid.Later, a counting of dead larvae after 3, 6, 12 and 24 h was performed. In addition,we investigated the effect of the aqueous extracts on the orientation of the aphidsby putting the latter in a position of choice between six leaflets, each treated with adifferent extract. In addition, a phytochemical screening was carried out to detectthe presence of saponins and polyphenols in the extracts studied. Through ourstudy, the extract obtained from S. africana at a concentration of 15% was the mosteffective with a mortality rate higher than 80% after 24 h of artificial infestation.As for the effect of the four extracts on the orientation of the cowpea aphid, theydid not attract the larvae massively. Regarding phytochemical screening,differences in the chemical composition of the analyzed extracts were observed.These differences may explain in part the variation of aphicidal effects of testedplant extracts

Population dynamics of aphids (Aphididae) on orange (Citrus sinensis ‘Thomson Navel’) and mandarin (Citrus reticulata ‘Blanco’)

Citrus fruits represent one of the most important fruit productions worldwide. However, they suffer from a numerous constraints. Aphids are among the causes of the decline in the production of citrus. In this study, the diversity of citrus aphids and their seasonal occurrence were explored on orange and mandarin, during 2012 and 2013, in an orchard located in Skikda province (Algeria). In total, six different aphid species were found during two years. The most common species was <em>Aphis spiraecola </em>Patch, 1914.  Climatic conditions had an important role in the infestation level by aphids. There were changes of aphid dynamics between the two years of the investigation. No aphids was recorded in six months in 2012 (January, June, July, August, September and December) and in three months in 2013 (January, February and August).  Besides, the number of identified aphid species increased from two to five. On the other hand, the orange trees seemed to be the most infested host species

Variation de l’interception des précipitations dans une chênaie à Quercus ilex L. des Aurès (Est algérien)

The distribution of precipitation in different fractions (i. e. throughfall, stemflow and interception) is the first interaction between the water cycle and the forest. These fractions have been evaluated over a period of three successive years under the cover of green oak (Quercus ilex L.) in Hamla forest, eastern Algeria using specific collection devices under cover for the throughfall, sealed on the trunks for the stemflow, and installed on bare soil for the precipitation. The results showed that the rate of water coming by throughfall was on average 57.4% of the precipitation. Stemflow represented a small fraction of precipitation (6.7%). The interception was high. It was on average 35.8% of the precipitation. In general, the interannual variability was significant. It is attributed mainly to the importance of the daily precipitation. The relationships between precipitation, stemflow and throughfall at the study site were assessed by linear regressions which revealed strong correlations between different fractions of water and precipitation. R2 varied between 0.74 and 0.99.La répartition des précipitations en différentes fractions d’égouttement, écoulement et interception est la première interaction entre le cycle de l’eau et la forêt. Ces fractions ont été évaluées pour une période de trois années successives sous le couvert de Quercus ilex L. dans la chênaie de Hamla dans les Aurès par un dispositif de recueil spécifique pour chaque fraction : sous couvert pour l’égouttement, scellé sur les troncs pour l’écoulement et installé sur un sol nu pour les précipitations. Les résultats ont montré que le taux des précipitations qui arrivent par égouttement se situe en moyenne à 57,4 % des précipitations. L’écoulement ne représente en moyenne qu’une faible fraction (6,7 %) des précipitations. Quant à l’interception, elle est très forte et elle représentait en moyenne 35,8 % des précipitations. La variabilité interannuelle de l’égouttement et de l’interception est importante. Elle est largement dépendante des précipitations journalières incidentes. Les relations entre les précipitations, l’écoulement et l’égouttement dans la station étudiée ont été appréciées par des régressions linéaires qui ont montré de fortes corrélations entre les différentes fractions d’eaux et les précipitations (R2 varie entre 0,74 et 0,99).Benhizia Toufik, Oudjehih Bachir, Lebbal Salim. Variation de l’interception des précipitations dans une chênaie à Quercus ilex L. des Aurès (Est algérien). In: Ecologia mediterranea, tome 44 n°1, 2018. pp. 97-108

APHICIDAL ACTIVITY OF PLANT EXTRACTS AGAINST APHIS FABAE (SCOPOLI, 1763) (HEMIPTERA : APHIDIDAE)

The excessive use of pesticides has created many problems for both human health and the environment. Therefore, the search for alternative methods has become a necessity. This study aims to test the effect of aqueous extracts of three plant species (Pistacia atlantica, Marrubium vulgare and Thymus algeriensis) on the larvae of the black bean aphid (Aphis fabae) found on the faba bean (Vicia faba) under laboratory conditions. With regard to extraction, two methods were adopted for the three plants: maceration and infusion. Each mixture of plant powder and distilled water was filtered and then diluted to obtain three concentrations (5, 15 and 25%). Three replications of 18 aqueous extracts and a control (distilled water) were tested for their insecticidal effect on the aphid mortalities by counting the dead larvae 6, 12 and 24 h after their placement on treated bean leaflets. In addition, phytochemical screening was carried out to detect the presence of saponins and polyphenols in the studied extracts. Through our study, the maceration extract from T. algeriensis at a concentration of 25% was the most effective, with a 70% of larval mortality rate after 24 h. With respect to phytochemical screening, differences in chemical composition were observed between the analyzed extracts (such as the absence of saponins in P. atlantica and its presence in T. algeriensis), which may have a role in the efficacy of the examined treatments. T. algeriensis extracts may be considered among the tools of integrated pest management (IPM) to minimize the use of synthetic pesticides