We collected 2297 egg batches of the pine processionary moth (Thaumetopoea pityocampa) during the period 1991-2018 from 44 sites in Bulgaria. The sampling sites were classified into three groups ...according to T. pityocampa phenological form (early, late and both forms) as well as in two groups of its range (historical and newly colonized areas). Seven primary egg parasitoids were identified: Ooencyrtus pityocampae, Baryscapus servadeii, Pediobius bruchicida, Anastatus bifasciatus, Eupelmus (Macroneura) vesicularis, Eupelmus (Macroneura) vladimiri and Trichogramma sp., and one hyperparasitoid, Baryscapus transversalis. The average impact of egg parasitoids (the percentage of parasitized host eggs) on T. pityocampa in Bulgaria was 13.8%. The two main parasitoids, O. pityocampae and B. servadeii, parasitized about 90% of the host eggs. The remaining parasitoids were of insignificant consequence to the parasitism of the T. pityocampa eggs, but in areas recently colonized by the pest, A. bifasciatus and Trichogramma sp. had a noticeable share (up to 33% of the impact). In old habitats of the host (areas colonized more than 10 years), the impact was almost two times higher than in new ones (15.3% vs. 8.6%). This could be attributed to B. servadeii, which was rare in newly colonized areas of T. pityocampa (impact 0.5%), but strongly dominant in old habitats (impact 7.2%). In contrast, O. pityocampae had a significant impact in new habitats (4.9%), which increased only slightly over time, reaching 6.0% in old habitats. There was no significant difference between the percentage of parasitism of the early and late form of the pine processionary moth (14.8% vs. 15.9%). However, there was a significant difference in the share of separate species in the parasitoid complex: in the early form, B. servadeii definitely dominated (63% of the infested eggs), while in the late form O. pityocampae dominated, although not so strongly (52% of the infested eggs). This difference is most likely due to the phenological characteristics of the parasitoids and the two forms of T. pityocampa. B. transversalis secondarily infested about 5% of the eggs of O. pityocampae and B. servadeii. This percentage was slightly lower for new habitats and habitats of the early form of pine processionary moth (3% and 4%, respectively). The impacts of the main parasitoids O. pityocampae and B. servadeii as well as the total impact of the parasitoid complex as a whole decreased with altitude. Conversely, the impacts of A. bifasciatus and Trichogramma sp. slightly increased with altitude probably due to the reduced competition of the main parasitoids.
Thaumetopoea pityocampa is the most important pine defoliator in the Mediterranean basin. Despite being attacked by a number of natural enemies, populations occur frequently at high density in ...several areas.
Egg parasitism was studied in 27 pine and cedar forests in Algeria, in relation to the host density (tents per tree) and the proportion of forest cover in the landscape.
Egg parasitism varied from 2% to 25%, accounted by two parasitoid species, the specialist Baryscapus servadeii and the generalist Ooencyrtus pityocampae.
Tent density was negatively correlated with parasitism by B. servadeii but not with that of O. pityocampae. Conversely, parasitism by O. pityocampae increased with the proportion of forest and agricultural cover, but not in the case of B. servadeii.
Maximum summer temperature showed no correlation with parasitism rates. Still, temperature frequently exceeded 40 °C during the period of adult parasitoid activity.
The low performance of the egg parasitoids at the southern edge of the host range could be explained by the reduced fecundity of the host, climate effects, and phenological mismatching between the parasitoids and the egg development. These and other factors potentially involved the need to be further explored with a long‐term study of population dynamics.
In urban and suburban areas larvae of the pine processionary moth, Thaumetopoea pityocampa (Denis and Schiffermüller), cause serious defoliation to Cedrus, Pinus, and Pseudotsuga trees and health ...problems to humans and domestic or farm animals by their urticating setae. In this study, we present the results of biennial trials (2015–2016) on the management of T. pityocampa infestations using commercial or LIFE-PISA prototype trunk barrier and adhesive trap devices in Greece (Attica and Volos), Spain (Valencia), and Italy (Molise). In Attica, for both 2015 and 2016, the commercial trunk barrier trap devices captured significantly more T. pityocampa wintering migrant larvae compared to the adhesive barrier trap devices, indicating their high capture capacity. The total performance of the trunk barriers trap devices was 99.8% in 2015 and 99.6% in 2016. In Volos and Valencia, no significant differences were recorded between captures in commercial and LIFE-PISA prototype trunk barrier trap devices. In the tests that were conducted in Molise, the commercial trunk barrier trap devices exhibited high effectiveness in capturing the wintering migrant larvae during their procession, before they reach the ground for pupation. Moreover, significantly fewer male adults were captured by pheromone trap devices during summer 2016 in comparison with 2015 in the experimental area. Similarly, significantly fewer nests were formed on the experimental area trees in winter 2016 and 2017 compared with 2015. Our results show the potential of the trunk barrier trap devices in the management of T. pityocampa numbers after long-term application in urban and suburban areas.
An Indicator Species of Global Warming in Bulgaria Zaemdzhikova, Gergana; Markoff, Ivailo; Mirchev, Plamen
Proceedings of the Bulgarian Academy of Sciences,
02/2022, Letnik:
75, Številka:
1
Journal Article
Odprti dostop
The pine processionary moth Thaumetopoea pityocampa (Denis & Schiffermuller, 1775) (Lepidoptera: Notodontidae) is one of the main pests in pine forests and an indicator species for global warming. ...Its expansion in Europe is considered one of the signals for changing climate. While other countries in the species range have a Mediterranean or oceanic climate, Bulgaria has a predominantly continental climate, which allows to see the pine processionary in a different light. For example, in Bulgaria, climate change is not causing expansion, but rather a habitat shift.
Habitat selection is especially important for pupae of holometabolous insects because this stage is usually immobile and to a certain extent unable to react to environmental changes. In the present ...study, we analyze how habitat and soil moisture determine the fate of pupae of the pine processionary moth Thaumetopoea pityocampa, a defoliator pest in pine woodlands of Europe and the Circunmediterranean region. The pine processionary moth pupates buried in the soil and can spend up to 9 years in an extra‐long diapause.
We considered the impact that different habitats, as well as the manipulation of soil water conditions in the preferred habitat (i.e. in bare ground with null or sparse herbaceous vegetation), can exert on pupation.
Less than half of the buried larvae successfully pupated, even in the most favourable habitats and soil water conditions, whereas, on average, 2.5% underwent extra‐long pupae diapause (2 years after pupation).
Although habitat influenced mainly pupation success and pupal survival, changing moisture conditions in the preferred habitat affected primarily the phenology of emergence, whereas pupal survival remained unaffected.
The results of the present study reveal the importance of both habitat and soil moisture on the pupal stage, providing valuable information with respect to adequately forecasting the effects of changes in climate or land use on the population dynamic of this important forest pest.
Thaumetopoea pityocampa (Denis and Schiffermüller) is a severe defoliator of various species of Pinus and Cedrus, while the urticanting hairs produced by its larvae cause public health problems for ...humans and pets. In the present study, we report results of trials (from summer 2015 until winter 2017) of mating disruption for management of T. pityocampa in different areas of Italy and Greece. Overall, the total number of male moths captured in mating disruption-treated plots over each season (70) was significantly lower than the respective number in untreated plots (780). The total number of winter nests was likewise significantly less in the mating disruption plots (13) compared with control plots (147). Our results indicate that mating disruption can be an important tool for judicious, insecticide-free control of T. pityocampa in urban, suburban, and recreational areas, where many alternative control measures are not available.
Pine processionary moth (Thaumetopoea pityocampa (Den. & Schiff.) / Thaumetopoea wilkinsoni (Tams)) is an oligofag defoliator in pine forests. In this study, the structure of egg batches, number of ...eggs, egg-laying patterns and egg hatching rates of the insect were investigated. A total of 841 egg-batches were collected from different calabrian pine Pinus brutia (Tenore) forests located in 11 provinces in Turkey. The average number of eggs in these sites was 194,7, the average rate of hatching was 63,7%. The average number of eggs at the low, middle and high elevations were found to be 183,7, 197,8 and 214,6; and the rate of hatching were 60,1%, 67,6% and 71,9%, respectively. The average number of eggs collected in lower, middle and upper parts of tree crowns were 185,8, 167,0 and 201,7 (mean=184,8); and the rate of hatching was 67,0%, 64,7% and 69,3% (mean=66,9%), respectively. Results indicated small differences in the number of eggs and hatching rate in relation to the position in crown and elevation, however, except for the distance to needle sheath in relation to elevation, the differences were not statistically significant at 95% significance level (p<0.05).
The pine processionary moth (PPM), Thaumetopoea pityocampa (Denis and Schiffermüller), is one of the most economically important forest defoliators in southern Europe. This pest is a univoltine ...oligophagous insect species, and the genus Pinus represents its main host. Investigations were carried out in the five-year period 2016–2020 in NW Italy. PPM males were monitored using commercial funnel traps baited with sex pheromone. The infestation index was recorded by counting the number of nests per tree. Temperature and rainfall were automatically recorded by 94 georeferenced meteorological stations. Adult presence was evaluated as the maximum number of captured individuals in a day, total captures during the season, the Julian day at max captures, or at first or last captures. Environmental variables (altitude, cumulative rain, and cumulative degree-days) and biological parameters were summarized using principal component analysis. Our study showed that the analyzed variables contribute to driving and affecting the PPM population dynamics, which also exhibited a year-to-year decrease. Due to the environmental and sanitary importance, all the data collected about the PPM will be useful to develop predictive risk models, as to deploy countermeasures in a timely and cost-effective manner.
CONTEXT: Various species of forest trees are commonly used for ornamental purposes and are therefore frequently found in nonforest ecosystems. They constitute an important component of the so-called ...trees outside forests (TOF). Not much is known, however, about the drivers of TOF spatial distribution either in urbanized or in agricultural landscapes since they are generally absent from forest inventories. OBJECTIVE: The present study focused on the spatial distribution of TOF across agricultural landscapes and their potential role in the dispersal of a forest pest insect, the pine processionary moth, Thaumetopoea pityocampa (PPM). METHODS: All the TOF belonging to the genera Pinus, Cedrus and Pseudotsuga were considered as potential hosts and inventoried within a 22 × 22 km study window. We fitted a nonstationary Poisson process to the empirical data and used the distance to the nearest building as a covariate. RESULTS: Both empirical and simulated data indicated that TOF associated to human artifacts/urbanized areas constituted the main source of landscape connectivity for the PPM in the open fields under study. Because they do not account for TOF, forest inventories dramatically underestimate landscape connectivity and provide an erroneous picture of the PPM habitat distribution. CONCLUSIONS: We conclude that TOF, especially the ornamental component, must be taken into account when it comes to understanding forest insect landscape dynamics or genetics. The omnipresence of TOF also suggests a potentially huge role in pest dispersal and invasive species expansion.
Defoliation by herbivores may alter the source:sink balance of trees leading to transient decreases in carbon (C) stores. When C stores are replenished concurrently with re-growth both processes may ...compete, store formation proceeding at the expenses of growth. However, the interactions between both processes are not fully understood. We investigated the effects of defoliation by the pine processionary moth (PPM, Thaumetopoea pityocampa Dennis and Schiff.) on the non-structural carbohydrate (NSC) and nitrogen (N) stores and the growth of Pinus nigra Arnold trees. Short-term effects were evaluated immediately after a PPM outbreak and at the end of the first growing season in trees suffering a range of defoliation damage. Long-term effects were explored by a 17-year-long PPM defoliation experiment, with 11 years of repeated defoliation treatments followed by 6 years of recovery. Defoliation by PPM was followed by transient NSC decreases, but trees were able to exceed initial NSC pools and compensate growth in just one growing season. Such recovery was linked to increased foliage N. Repeated severe defoliations decreased growth and survival of trees in the long-term, but trees increased starch allocation to stems. Defoliation led to an accumulation of C storage compounds in P. nigra trees irrespective of their ability to re-grow. In trees included in the short-term experiment, the accumulation of stores proceeded concurrently with re-growth. However, the repeated severe defoliations included in our long-term experiment impaired the growth of trees, surplus C being accumulated as stores. These results indicate that, growth declines in pines defoliated by PPM are not due to C (source) limitation but may respond to the reduced sink strength of growing meristems due to defoliation, and thus, a decrease in C allocation to growth.
PDF
