Aphids on almond and peach: preliminary results about biology in different areas of Tunisia

Four aphid species are known to colonize peach and almond in Tunisia: Hyalopterus pruni species complex, Myzus persicae Sulzer, Brachycaudus amygdalinus Shouteden and Pterochloroides persicae Cholodkovsky. Eggs identification, date of lay and effect of orientation on egg laying were described. Brief information about biology, preferential host, distribution and growth rates are given for each species

Aphid on Almond and Peach in Tunisia: Species, Bioecology, Natural Enemies and Control Methods

Aphids are among the most obnoxious pests of almond and peach in Tunisia. Accurate control of these insect pests requires the determination of their major species as well as the thorough understanding of the biology and identification of their major natural enemies. The scope of this chapter is to identify the main aphid species infesting almond and peach in Tunisia, to describe their biology, to determine their natural enemies and to study their efficiency as biological agents. A field survey was carried out during 2007–2016 period at Almond and Peach orchards in Tunisia. Results demonstrated the presence of Hyalopterus pruni Geoffroy, Hyalopterus amygdali Blanchard, Brachycaudus amygdalinus Schouteden, Myzus persicae Sulzer, Brachycaudus schzartwi Borner and Pterochloroides persicae Cholodkovsky. Biological study of recorded species demonstrated the presence of holocyclic and anholocyclic life cycle depending on host trees and aphid species. For predators, four families (Coccinellidae, Syrphidae, Chrysopidae, Cecidomyiidae) and one parasitoid and two entomopathogenic fungi species were identified. For control of Pterochloroides persicae, results showed that Pauesia antennata Mukergi was more efficacy than Coccinella algerica Kovar. This parasitoid should be reared and used in future integrated pest management program in almond and peach orchard in Tunisia

Toxicity of the active fraction of Pergularia tomentosa and the aggregation pheromone phenylacetonitrile on Schistocerca gregaria fourth-instar nymph: effects on behavior and acetylcholinesterase activity

Chemical insecticides remain the most used approach in locust control although they present a serious menace to human health and the environment. The search for alternative control methods, efficient and environmentally friendly, has become indispensable. The aim of this work is to study the effect of the aggregation pheromone, phenylacetonitrile, alone or in combination with the active fraction of Pergularia tomentosa on Schistocerca gregaria fourth-instar nymph. Toxicity bioassays showed that the combination of phenylacetonitrile with the active fraction of P. tomentosa significantly increased nymph mortality. Results also showed that the aggregation pheromone caused significant mortality especially after 6 hours of exposure. The pheromone also caused neurotoxic effects on S. gregaria nymph due to the disturbance of the acetylcholinesterase activity. We also noted the presence of cannibalism phenomenon. Phenylacetonitrile seems to have an effect on phase ployphenism of S. gregaria imagos that exhibit specific traits to the solitarious phase

Effects of different varieties of pepper (Capsicum annum L.) on the biological parameters of the green peach aphid Myzus persicae Sulzer (Hemiptera, Aphididae) in Tunisia

The green peach aphid Myzus persicae Sulzer (Hemiptera, Aphididae) is an important pest of pepper, Capsicum annum (Solanaceae), with infestations by this aphid resulting in serious economic damage. Commonly, biological parameters are used to compare insect fitness on different varieties of pepper. Effect of rearing M. persicae on nine varieties of pepper (Anamex, Balconi, Bami, Chargui, Garn ghzel, Italico, J27, Starter and Torero) on the population density and percentage infestation it achieves, and its mean relative growth rate (MRGR) and generation time were studied under laboratory conditions. The highest population density, maximum percentage infestation (92.93%), minimum generation time (10.95 days) and highest MRGR (0.063) were recorded on the variety Chergui and the lowest population density, minimum percentage infestation (51.4%), minimum MRGR (0.043) and maximum generation time on the variety Anamex

Identification of two entomopathogenic fungi naturally infecting Pterochloroides persicae (Cholodkovsky 1899) (Hemiptera, Aphididae) in peach orchards in Tunisia

Symptoms of mycosis of Pterochloroides persicae (Cholodkovsky 1899) (Hemiptera, Aphididae) in a peach and almond orchard were recorded in April 2011. The causal agent was morphologically identified. Polymerase chain reaction (PCR) of the internal transcribed spacer region (ITS1 and ITS4) was used for molecular identification and verification of the morphological determination. Both methods gave consistent results and we recorded for the first time the natural occurrence of two fungal species belonging to the order Hypocreales (Phylum Asocomycota); Beauveria bassiana Viull (Hypocreales, Cordycipitacae) and Metacordyceps liangshanensis (Hypocreales, Clavicipitaceae)

Expansion in the distribution of Pauesia silana Tremblay (Hymenoptera, Braconidae, Aphidiinae), across North Africa, a recent discovery in Tunisia

View on Scopus The occurrence of Pauesia silana Tremblay, as an aphid parasitoid (Hym., Braconidae, Aphidiinae) in Tunisia is documented. The parasitoid was found in association with the Aleppo pine aphid, Cinara palaestinensis Hille Ris Lambers, infesting Pinus halepensis. Specimens were collected by the rearing of the mummified aphids from the colonies infested the pine trees in the Arboretum of the Institut Supérieur Agronomique Chott Mériem (ISA CM - Tunisia) during March–April 2021. A brief diagnosis is provided for the recorded parasitoid. This is the first record of a Pauesia species in Tunisia (out of the purposeful introduction of Pauesia antennata Mukerji). Two secondary parasitoids including Asaphes vulgaris Walker and Pachyneuron aphidis (Bouché) (Hym., Chalcidoidea, Pteromalidae) have also emerged from the mummified aphids. The known Cinara aphids and their associated parasitoids in the North African country are reviewed. Both Aleppo pine aphid and the newly detected parasitoid might be considered exotic species in North Africa, sourced from a recent accidental introduction inside the Mediterranean area, or a horizontal expansion across the North African countries

Chemical Constituents and Toxicity of Essential Oils from Three Asteraceae Plants against Tribolium confusum

Plants produce a high diversity of secondary metabolites with a prominent function in the protection against pests and pathogens. In this work, we studied the chemical composition and the effect of six essential oils extracted from three Asteraceae species (Heteromera fuscata, Coleostephus myconis and Mauranthemum paludosum) on nutritional indexes, adult emergence and larva and adult toxicity of Tribolium confusum. Flower and leaf essential oils were obtained by hydrodistillation. The study of their chemical composition was carried out by GC-MS. The results showed that they are rich on monoand sesquiterpens. The consumption of essential oils mixed with artificial diet of T. confusum larvae showed that H. fuscata leaf essential oil delayed the insect growth, reduced the food consumption and exhibited significant food deterrent index (0.02 ± 0.01 mg/mg/j, 0.05 ± 0.02 mg/mg/j, and 71.20 ± 19.22%, respectively) on treated larvae. Topical application of Asteraceae essential oils on pupae less than 24 h of age caused malformation on emerged adults. The highest level of malformation (18%) was induced by C. myconis leaf essential. Topical application of those essential oils on T. confusum adults (10 and 14 days-old) showed higher toxicity. The highest mortality of about 41% was recorded 7 days post-treatment on adults treated with essential oils from M. paludosum leaves. These preliminary results could represent the basis for further investigations on the susceptibility of the other developmental stages and elucidation of the mode of action of mono- and sesquiterpenoids against these insect pests

Variation of Chemical Composition in Flowers and Leaves Essential Oils Among Natural Population of Tunisian Glebionis coronaria (L.) Tzvelev (Asteraceae)

The aim of this study was to assess the percentage and constituents variations in flowers and leaves essential oil of three Glebionis coronaria (L.) Tzvelev population, growing wildly in three different ecotypes (Utique, M'saken, and Sahara Lektar) in Tunisia. The chemical compositions of these essential oils were analyzed by the GC and GC/MS systems. Qualitative and quantitative differences were recorded between essential oils extracted from plants collected from the three geographical provinces and between organs of the same plant (leaves and flowers). In fact, 161 components representing 87.2 – 96.5% of the whole oils were identified. Myrcene (3.2 – 35.7%), (Z)-β-ocimene (0.6 – 23.0%), camphor (0.6 – 17.2%), cis-chrysanthenol (0 – 6.9%), cis-chrysanthenyl acetate (1.1 – 17.9%), isobornyl acetate (1.6 – 3.5%), (E)-β-farnesene (0 – 6.0%), germacrene D (0 – 8.7%), and (E,E)-α-farnesene (0.7 – 12.4%) were the predominant components in the oils. These major constituents occur in different amounts depending on the organs (leaves or flowers) and the geographical origin of the plant. The chemotaxonomic usefulness of these data was discussed according to results of principal component analysis (PCA). The scores, together with the loadings, revealed a different chemical pattern for each population