Francesco Croci

Asian chestnut gall wasp in Tuscany: gall characteristics, egg distribution and chestnut cultivar susceptibility

1 Preliminary investigations were carried out on Dryocosmus kuriphilus Yasumatsu on Castanea sativa Miller in Tuscany to assess variations in gall characteristics in coppice and high forest at two crown heights (height < 2 or 2–6 m), influence of bud size and bud position on oviposition rates and susceptibility of three cultivars. 2 Gall size may depend on various factors, including wasp population density. In the present study area, small galls (with one or two cells) were the most numerous in 2008, whereas larger galls (with more than three cells) prevailed in 2009. 3 Dryocosmus kuriphilus oviposition occurrence was influenced by both bud size and bud position. Buds with eggs tended to be larger in size compared with bud without eggs, suggesting that D. kuriphilus females prefer to lay eggs in larger buds (approximately 6 mm3) compared with smaller buds (approximately 3 mm3). The mean number of eggs per bud tended to decrease from the apical bud toward the basal bud. 4 Three C. sativa cultivars, Carpinese, Fusca and Cesurone, were examined. Fusca grafts had significantly more galls compared with Carpinese and Cesurone, whereas Cesurone grafts had more larvae per bud compared with Carpinese and Fusca. Overall, the Carpinese cultivar may be less susceptible to D. kuriphilus galling compared with the Fusca and Cesurone cultivars.

Cone and Seed Pests of Pinus pinea: Assessment and Characterization of Damage

ABSTRACT Cone and seed insects have played a key role in the decline of stone pine nut production in Italy. To evaluate the impact caused by native Palearctic and exotic insects, a greater knowledge of pest symptoms is required. During 2008–2009, first and second-year stone pine cones, as well as the seeds produced, were examined in Tuscany (Italy) to assess viability. Insect damage was characterized based on external signs on the cones and seed endosperms, and the impact of recorded insect species on nut production was evaluated. In the current study, cones attacked by anobiid beetles and Dioryctria spp. were observed, as well as asymptomatic dead cones and cones with resin drops and patches, that could not easily be related to a damaging agent. As regards the anobiid beetles, adults of Ernobius parens (Mulsant and Rey) and E. impressithorax Pic emerged from cones in laboratory rearing. A low number of cones damaged by Dioryctria spp. was recorded whereas high percentages of cones showed resin exudates. The presence of resin cannot be definitely related to a damaging agent, although the feeding activity of Leptoglossus occidentalis Heidemann could be one of the reasons. Damage by L. occidentalis was assessed by seed observation. Most of the seeds displayed tissues that had been damaged by this pest.

Cork oak pests: a review of insect damage and management

Key messageCork oak decline is widespread in all its distribution range and seems to be triggered mainly by both mismanagement and unfavorable climatic factors. As a result, cork oak forests become susceptible to pest attack, which accelerates the onset of decline. Pest management strategies for this valuable and highly biodiverse ecosystem are examined in this review, taking into account the main insect pests and how their impact on cork oak forests is affected by climate change. While monitoring pests may provide the tools to predict the transition from endemic to epidemic insect populations, forestry practices (sanitary felling), biological control, and trapping are some of the most promising measures in protecting cork oak forests.ContextOver the last decades, cork oak (Quercus suber L.) decline has affected millions of trees throughout its distribution range. Cork oak is a typically Mediterranean species remarkably relevant for the biodiversity and landscape conservation of vast evergreen oak forests. Cork oak is also well known and highly valued for cork production. Climatic changes, management practices, and biotic factors, particularly plant pathogens and insect pests, play a decisive role in tree death and market devaluation of cork.AimsHere, we review the major insect pests possibly involved in cork oak decline, while discussing pest management strategies.MethodsA survey of the current literature was performed to identify major insect pests affecting cork oak trees, as well as to establish the most promising pest management strategies under climate change.ResultsMany authors seem to agree that the decline is triggered by both anthropogenic and abiotic factors, such as the mismanagement of cork oak forests and unfavorable climate (high temperatures and droughts). Consequently, trees become susceptible to pests and pathogens, which accelerate the onset of decline.ConclusionSince a further increase in temperatures and droughts is expected, developing adequate management strategies to adapt cork oak trees to climate change, while simultaneously preventing and reducing insect pest attacks, is of foremost importance in the effort to conserve these unique and highly diverse ecosystems.

Field response of non‐target beetles to Ips sexdentatus aggregation pheromone and pine volatiles

Although mass trapping cannot be a definitive control measure, it is one of the few ones available to contain the destruction of millions of cubic metres of conifer forests perpetrated every year worldwide by bark beetles. However, using bark beetle aggregation pheromones during both monitoring and control programs may negatively affect other saproxylic insects. The aim of this study was to describe the response of both Ips sexdentatus and its saproxylic beetle associates, especially predators, to traps baited with a commercial blend of I. sexdentatus aggregation pheromone. Furthermore, the usefulness of adding pine volatiles, such as (−)‐α‐pinene and ethanol, to the pheromone was discussed. The commercial blend proved to be attractive to I. sexdentatus adults, both when used alone and together with pine volatiles. Pheromone attractiveness, however, was lessened by the addition of the volatiles. The pheromone blend proved to be attractive to Thanasimus formicarius, as well as to other predator species. Overall, although during our study, traps baited only with (−)‐α‐pinene and ethanol attracted some predator specimens, I. sexdentatus pheromone traps were more attractive. Our study confirms that calendar differences in flight activity between the bark beetle and its predators are substantial; therefore, they should be taken into account when planning control measures. According to our data, the commercial blend of I. sexdentatus pheromone seems to be the most effective, among the baits used, in catching I. sexdentatus adults, while reducing the impact on T. formicarius.

Effects of climate on pine processionary moth fecundity and on its egg parasitoids

Abstract Climate change may be affecting the fecundity of phytophagous insects as well as impacting their natural enemies. However, temperature impacts these two insect groups differently, disrupting population regulation mechanisms, and ultimately, possibly culminating in an outbreak of the host. The pine processionary moth (PPM) is one of the most harmful insects of the Mediterranean basin. Not only are PPM larvae harmful to plants, but they are also dangerous to humans because of their urticating hairs. Although some information is available on climate change effects on the PPM, little is known about its potential effects on PPM egg parasitoids, especially on their distribution range or on their role in controlling PPM populations. The aim of this article was to verify the effects of climate on PPM fecundity and on its egg parasitoids. Our results show that climate warming may affect the PPM positively, but not its egg parasitoids. Specifically, during our study mild winters directly favored the PPM, while increasing summer temperatures (over 30°C) also favored the PPM indirectly, by decreasing parasitism rates. We predict that ever‐milder winters will not only favor PPM development, but also encourage it to spread in otherwise previously inhospitable environments.

Population Dynamics of Native Parasitoids Associated with the Asian Chestnut Gall Wasp (Dryocosmus kuriphilus) in Italy

Native parasitoids may play an important role in biological control. They may either support or hinder the effectiveness of introduced nonnative parasitoids released for pest control purposes. Results of a three-year survey (2011–2013) of the Asian chestnut gall wasp (ACGW) Dryocosmus kuriphilus Yasumatsu (Hymenoptera: Cynipidae) populations and on parasitism rates by native indigenous parasitoids (a complex of chalcidoid hymenopterans) in Italian chestnut forests are given. Changes in D. kuriphilus gall size and phenology were observed through the three years of study. A total of 13 species of native parasitoids were recorded, accounting for fluctuating parasitism rates. This variability in parasitism rates over the three years was mainly due to the effect of Torymus flavipes (Walker) (Hymenoptera: Torymidae), which in 2011 accounted for 75% of all parasitoid specimens yet decreased drastically in the following years. This strong fluctuation may be related to climatic conditions. Besides, our data verified that parasitoids do not choose host galls based on their size, though when they do parasitize smaller ones, they exploit them better. Consequently, ACGWs have higher chances of surviving parasitism if they are inside larger galls.