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Depuis la découverte du charançon rouge du palmier Rhynchophorus ferrugineus en Tunisie en décembre 2011, ce ravageur est devenu invasif et mortel pour les palmiers. L’apparition tardive des symptômes représente l’obstacle majeur qui entrave l’efficacité de la lutte. Afin de mieux contrôler ce ravageur, un élevage de masse a été réalisé pour étudier ses traits d’histoire de vie (THV). Allant de l’œuf à l’adulte sur milieu artificiel et dans les conditions de laboratoire, la durée d’incubation des œufs est de 5 jours, celle de développement larvaire est de 119 jours et la période nymphale est de 16 jours. La longévité totale de la femelle est de 74 jours, tandis que celle des mâles est de 94 jours. Treize stades larvaires ont été identifiés grâce au suivi des différents traits d’histoire de vie : la taille des individus (adultes et larves), la mue larvaire, la largeur de la capsule céphalique et le poids des larves. Cependant, l’analyse discriminante canonique ne peut pas séparer d’une manière statistique claire les différents stades larvaires ce qui montre que la forme larvaire de ces coléoptères est continue dans le temps. Un fort dimorphisme sexuel est associé au rostre des insectes adultes : les mâles ont un rostre significativement (p < 0.0001) plus court (8.03 ± 0.11 mm) que les femelles (9.71 ± 0.338 mm). Cela constitue un critère taxonomique intéressant auquel il faut lier, chez le mâle, la présence de soies sur la région dorsale apicale du rostre.

Lentisk dieback has been commonly observed in Tunisian forests. Nevertheless, the identity of the parasitic factors involved in this phenomenon has not yet been reported. Thus, in order to characte...

Eucalyptus is a plant frequently present and cultivated in arid regions because of its high adaptation to drought. Furthermore, it is known by its numerous species which represents a great opportunity to choose several tolerant species with variable uses. Therefore, the choice of species, hybrids or genotypes resistant to aridity becomes a necessity before any plantation in regions and countries characterized by semi-arid, arid and Saharan climates. Our review shows an important effect of drought on anatomical, physiological and biochemical parameters of Eucalyptus spp. Indeed, water stress acts directly on growth, yield and response to pests. However, the response to drought varies significantly among species, genotypes, hybrids and clones. This result represents a field for the selection of eucalypts tolerant and adapted to water deficit or climate change.

The enemy release hypothesis predicts that alien populations are more vigorous and grow faster in introduced areas than within their natural range due to lack of natural enemies. An extension of this theory would be that the lack of natural enemies on an herbivore species will indirectly increase the number of host plant species that it can infest. The eucalyptus gall wasp Ophelimus maskelli is a recent introduction to the Mediterranean basin. Its arrival was followed after about two years by its parasitoid, Closterocerus chamaeleon. We evaluated the range of hosts used by the gall wasp by surveying 50 Eucalyptus species, 37 Eucalyptus hybrids and 18 E. globulus half-sibling families, before and after the establishment of the parasitoid. We found a consistent reduction in the observed host range of the gall wasp after the establishment of the parasitoid with a reduction of 83% on Eucalyptus species, 84% on hybrids, and 94% on E. globulus half-siblings. Host range narrowed down from 18 to three closely-related host species, all in the section Exsertaria, series Exsertae, E. camaldulensis, E. tereticornis and E. rudis, which are probably the standard hosts of O. maskelli. In the remaining affected species the intensity of attack decreased significantly in all studied regions. These findings show that, besides the direct gains from classical biological control, there may be indirect benefits through a natural-enemy-induced reduction in the range of host plants used by herbivorous insect pests.

Host preferences and reproductive performance of the juniper bark beetle, Phloeosinus bicolor (Brulle), on logs from different parts of the bole of indigenous Cupressus sempervirens L. (Cupressaceae) and exotic C. arizonica Greene and C. sempervirens var. atlantica (Gaussen) Silba were experimentally studied in the field and laboratory in Tunisia. Attack densities were around 1/dm2 in the field, fecundity was 10 – 25 eggs per female’s gallery, with a sex ratio close to 1. There was no effect of cypress taxon or log category on host selection or attack parameters (attack density, density of systems, density of galleries, rate of successful attacks), although values for C. sempervirens tended to be higher than those for C. arizonica. Reproductive performance (gallery length and fecundity) was highest in C. arizonica and lowest in C. sempervirens var. atlantica, with C. sempervirens in an intermediate position; egg densities did not differ. Gallery length and fecundity showed a significant linear correlation but were lower in C. sempervirens var. atlantica than in the other two taxa. Thus there seems to be no relationship between host preference and host suitability in P. bicolor: its ability to choose and oviposit in various cypress taxa fits with its polyphagous status.

The two eucalyptus borers Phoracantha semipunctata and P. recurva were accidently introduced in Tunisia in 1962 and 1999, respectively. Their relative distribution is still unknown and very little is known about their preferences and performances in various host species under different Tunisian climates. We combined field data and laboratory follow-up, in order to define their present distribution, their relative abundance and to test the effects of sites and Eucalyptus species on attack density, reproductive and developmental performances and productivity of insects. The study was carried out in Eucalyptus plantations of ten localities ranging from humid to arid. Choice preference and colonization of various selected Eucalyptus species by the two borers were studied with standing trap trees and trap logs. Tree species differed among localities, but all localities contained at least one of the two species E. gomphocephala and E. camaldulensis, both being well appreciated by the two Phoracantha species. It appeared that both beetle species were present in all localities but P recurva was dominant over P semipunctata everywhere. Insect characteristics depended on attack localization on tree stem; attack densities were higher on the lowest than on the upper parts. It is perfectly coherent that the density of emerging beetles correlated positively with attack density, number of young larval galleries, larval survival and adult success in the trap tree experiment. High larval survival and adult success resulted in high offspring productivity. Insect parameters, especially the intensity of infestation, depended on locality but without relation with the climatic areas.

Closterocerus chamaeleon (Girault) (Hymenoptera Eulophidae), parasitoid of the Eucalyptus gall wasp Ophelimus maskelli (Ashmead) (Hymenoptera Eulophidae) has been recorded for the first time in Tunisia in July 2007. This record suggests that 14 months after its release in Sicily, in May 2006, it has spread over Sicily Channel.

Pine processionary moth, Thaumetopea pityocampa, is a model insect indicator of global warming, the northwards and upwards range expansion of this Mediterranean species being directly associated with the recent warming up. The knowledge about the drivers of moth expansion is synthesized. A first standardized mapping of the northern expansion edge, from Western Europe to Turkey, is presented, then detailed for 20 countries of Europe, Asia Minor and North Africa, including future trends. Additional data about the responses of the other Thaumetopoea species are given. Finally, the chapter points out the importance of the man-mediated introductions in the expansion process. © Éditions Quæ, 2015.

It is difficult to find a genus of Lepidoptera showing the high variability of life history traits observed in Thaumetopoea. There are typical summer feeding close to winter feeding species, and in one special case a recent switch has been detected even within one species, the pine processionary moth, indicating that the natural history traits are constantly evolving at a fast rate. There are species adapted to cold conditions of high mountains and high latitude close to truly Mediterranean and sub-desert region species. All species have gregarious behaviour as larva and are protected against vertebrate predators by urticating setae.

BACKGROUND: Essential oils extracted from aromatic and medicinal plants have many biological properties and are therefore an alternative to the use of synthetic products. The chemical composition of essential oils from two medicinal plants (Eucalyptus globulus and E. lehmannii) was determined and, their insecticidal effects on the third and fourth larval stages of Orgyia trigotephras were assessed. RESULTS: Larvae were collected from Jebel Abderrahmane (North-East of Tunisia), conserved in groups of 50/box (21 × 10 × 10 cm) at a temperature of 25°C. Larvae were tested for larvicidal activities of essential oils. Each oil was diluted in ethanol (96%) to prepare 3 test solutions (S1 = 0.05%, S2 = 0.10% and S3 = 0.50%). Essential oils were used for contact, ingestion and Olfactory actions and compared to reference products (Bacillus thuringiensis and Decis). Olfactory action of essential oils shows that larvae mortality is higher than contact action, lower than ingestion action. MTM and FTM of S3 of E. lehmannii were respectively 1 h 32 min and 1 h 39 min are higher than those of E. globulus (MTM = 51 min and FTM = 1 h 22 min 34 sec). Contact action of E. lehmannii oil shows low insecticidal activity compared to E. globulus. MTM are respectively (1 min 52 sec and 1 min 7 sec), FTM are (2 min 38 sec, 1 min 39 sec), are the shortest recorded for S3, on the third stage of larvae. The fourth stage of larvae, MTM are (2 min 20 sec and 2 min 9 sec), FTM are (3 min 25 sec, 3 min 19 sec). Ingestion action of essential oils is longer than the contact action, since the time of death exceeds 60 minutes for all species. CONCLUSION: Results shows that essential oils have a toxic action on nerves leading to a disruption of vital system of insects. High toxic properties make these plant-derived compounds suitable for incorporation in integrated pest management programs.

Nar kelebegi Virachola livia, 2006 yilinda ilk kez kaydedildigi zamandan bu yana Tunus’ta narlar icin cok zararli bir bocek olmustur. Ancak, V. livia’nin sadece nardan degil ayni zamanda Gabes bolgesinde (Tunus’un Guneydogusu) cok yaygin bir bitki turu olan Acacia farnesiana’nin tohumlarinda da beslendigi tespit edilmistir. Nisan ve Temmuz 2013 arasinda Metwia bolgesinde (Gabes’te en cok istila edilen bolge) gerceklestirilen bu calismanin amaci, A. farnesiana ile beslenen V. livia boceklerinin ergin ucusu, yumurtlama, larva gelisimi, pupa ve nesil sayisi gibi bazi biyolojik ozelliklerini acikliga kavusturmaktir. A. farnesiana turunde yer alan farkli yesil Akasya agaclarinin tohumlarindan haftalik olarak rasgele ornekler alinmistir. Larvalari ve pupa evresini saymak icin tohumlar kurutulduktan sonra yumurtalari belirlemek uzere laboratuvarda binokuler ile incelenmistir. Ergin boceklerin aktivitesi ve cikisi, hem sahada hem de laboratuvarda deney aleti ile izlenmistir. Ilk sonuclar, A. farnesiana’nin Guney Tunus’ta V. livia icin ana ve birincil konukcu bitki oldugunu gostermektedir. Bu bocekler A. farnesiana uzerinde uc senelik nesil gelistirmektedir ve her senelik nesil yaklasik dort hafta surmektedir. Ilk nesil nisan ayinin sonlarinda baslayip mayis ayinin sonunda omrunu tamamlamaktadir. Ikinci nesil, mayis sonlarinda baslayip bir sonraki ayin yirmi besinci gunune kadar surmektedir. Ucuncu nesil ise en son aydan baslayip temmuz ortasina kadar devam etmektedir. Temmuz itibariyle agaclarda yesil tohum zarflari olmadigi icin, kelebekler alternatif konukcu olan nar bitkilerine goc etmektedir. Anahtar kelimeler: Virachola livia, Acacia farnesiana, Biyo-ekoloji, Tunus