Numerous studies have shown that the genetic diversity of species inhabiting temperate regions has been shaped by changes in their distributions during the Quaternary climatic oscillations. For some species, the genetic distinctness of isolated populations is maintained during secondary contact, while for others, admixture is frequently observed. For the winter moth (Operophtera brumata), an important defoliator of oak forests across Europe and northern Africa, we previously determined that contemporary populations correspond to genetic diversity obtained during the last glacial maximum (LGM) through the use of refugia in the Iberian and Aegean peninsulas, and to a lesser extent the Caucasus region. Missing from this sampling were populations from the Italian peninsula and from North Africa, both regions known to have played important roles as glacial refugia for other species. Therefore, we genotyped field‐collected winter moth individuals from southern Italy and northwestern Tunisia—the latter a region where severe oak forest defoliation by winter moth has recently been reported—using polymorphic microsatellite. We reconstructed the genetic relationships of these populations in comparison to moths previously sampled from the Iberian and Aegean peninsulas, the Caucasus region, and western Europe using genetic distance, Bayesian clustering, and approximate Bayesian computation (ABC) methods. Our results indicate that both the southern Italian and the Tunisian populations are genetically distinct from other sampled populations, and likely originated in their respective refugium during the LGM after diverging from a population that eventually settled in the Iberian refugium. These suggest that winter moth populations persisted in at least five Mediterranean LGM refugia. Finally, we comment that outbreaks by winter moth in northwestern Tunisia are not the result of a recent introduction of a nonnative species, but rather are most likely due to land use or environmental changes.

& Key message Operophtera brumata L. performance varies among three Mediterranean oak species. Quercus canariensis Willd is more susceptible to infestation probably due to its (i) early leafing, (ii) high nutritional value for the larvae, and (iii) widespread abundance. & Context Larvae of Operophtera brumata were observed for the first time in an outbreak in Tunisia affecting Quercus canariensis, Quercus afares Pomel, and Quercus suber L. Due to its polyphagous nature and the important ecological and economic damage it causes, it is most relevant to understand its interaction with North African oaks species. & Aims In this paper, budburst phenology of the three oak species, larval performance, and genetic patterns of O. brumata were studied in northwestern Tunisia. & Methods In the spring of 2010, 2011, and 2012, budburst phenology of host species and larval densities were monitored weekly. Larval performance of O. brumata on the three oak species was analyzed. DNA extraction, PCR, and DNA sequencing were performed. & Results Budburst of Q. canariensis and Q. afares was earlier than Q. suber. Q. canariensis was the most infested host. Larvae which fed on Q. canariensis had faster development, lower mortality, and higher pupal weight than larvae fed on Q. afares and Q. suber. Molecular analyses showed that Tunisian haplotypes were not different from those in Spain, Italy, and Germany. & Conclusion Results indicated differences in larval performance. Q. canariensis was the most favorable host species. Its high density in the field and early leafing coinciding with larval hatching made this species particularly susceptible.

Tortrix viridana is one of the most important defoliators of oak trees. In 2006 and 2007, this insect caused significant defoliations of oak forests in the Northwestern Tunisia. This work aims at studying the insecticidal activity of essential oils of Cupressus arizonica and C. sempervirens on 3rd, 4th and 5th instars larvae of T. viridana by the contact test. Three different concentrations of essential oils (0.05%, 0.1% and 0.5%) were used to test their contact effectiveness; the Deltamethrin and the ethanol were used as positive and negative controls. Larvicidal activity was determined by measuring the Mean Mortality Time (MMT) to kill 100% of larvae. A total of 28 chemical compounds have been identified from C. arizonica and 20 chemical compounds from C. sempervirens. The difference in MMT of the 3rd instar larva was highly significant between the 3 concentrations of the two tested essential oils, the negative and positive controls. In fact, the concentration (0.5%) was more efficient than the two other concentrations with a MMT=1h31min12s for C. arizonica and 5h11min20s for C. sempervirens. The same results were observed for the 4th (MMT=3h23min24s (Ca) and 4h1min (Cs)) and 5th (MMT= 3h23min24s (Ca) and 4h01min (Cs)) instars. The results revealed that the essential oil of C. arizonica was more effective than C. sempervirens. Therefore, it is recommended to use the essential oil of C. arizonica and not that of C. sempervirens, given its insecticidal efficiency on the 3rd instar larva of T. viridana