Management of the Pine Processionary Moth, Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae), in Urban and Suburban Areas: Trials With Trunk Barrier and Adhesive Barrier Trap Devices

Discovering allatostatin type-C receptor specific agonists

Currently, there is no pesticide available for the selective control of the pine processionary moth (Thaumetopoea pityocampa-specific), and conventional methods typically rely on mechanical techniques such as pheromone traps or broad-spectrum larvicidal chemicals. As climate change increases the range and dispersion capacity of crop and forest pests, outbreaks of the pine processionary occur with greater frequency and significantly impact forestry and public health. Our study is carried out to provide a T. pityocampa-specific pesticide targeting the Allatostatin Type-C Receptor (AlstR-C). We use a combination of computational biology methods, a cell-based screening assay, and in vivo toxicity and side effect assays to identify, for the first time, a series of AlstR-C ligands suitable for use as T. pityocampa-specific insecticides. We further demonstrate that the novel AlstR-C targeted agonists are specific to lepidopteran larvae, with no harmful effects on coleopteran larvae or adults. Overall, our study represents an important initial advance toward an insect GPCR-targeted next-generation pesticide design. Our approach may apply to other invertebrate GPCRs involved in vital metabolic pathways.

Developing traps for the overwintering tree-of-heaven weevils Eucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae)

BACKGROUND

The tree-of-heaven root and trunk weevils, Eucryptorrhynchus scrobiculatus (TRW) and E. brandti (TTW) are important boring pests of Ailanthus altissima in China. Overwintering TRW and TTW adults can continue to damage A. altissima trees and reproduce after they emerge from the soil each year. There is a lack of studies regarding the development of control measures during the overwintering period. A polyethylene terephthalate bottle trap (PETBT) and corrugated paper box trap (CPBT) were evaluated for their ability to trap TRW and TTW adults descending from trees to overwinter in the soil in Wutongshu and Shabatou locations in Ningxia, China.

RESULTS

Significantly more overwintering TRW adults were caught by the PETBT than the CPBT. There were no significant differences in the TTW captures in PETBT when compared to the CPBT. Both PETBT and CPBT have little effect on trapping overwintering TTW adults. Further trapping studies showed that PETBT treatments significantly reduced overwintering TRW numbers caught in population monitoring trap nets placed on the A. altissima tree trunks (an average annual reduction of 42% than the untreated trees).

CONCLUSION

These results demonstrate that PETBT is effective for trapping overwintering TRW adults. PETBT could be recommended as an alternative for managing TRW in the framework of integrated pest management. © 2021 Society of Chemical Industry.

When insect pests build their own thermal niche: The hot nest of the pine processionary moth

Temperature strongly drives physiological and ecological processes in ectotherms. While many species rely on behavioural thermoregulation to avoid thermal extremes, others build structures (nests) that confer a shelter against climate variability and extremes. However, the microclimate inside nests remains unknown for most insects. We investigated the thermal environment inside the nest of a temperate winter-developing insect species, the pine processionary moth (PPM), Thaumetopoea pityocampa. Gregarious larvae collectively build a silken nest at the beginning of the cold season. We tested the hypothesis that it provides a warmer microenvironment to larvae. First, we monitored temperature inside different types of nests varying in the number of larvae inside. Overall, nest temperature was positively correlated to global radiation and air temperature. At noon, when global radiation was maximal, nest temperature exceeded air temperature by up to 11.2-16.5 °C depending on nest type. In addition, thermal gradients of amplitude from 6.85 to 15.5 °C were observed within nests, the upper part being the warmest. Second, we developed a biophysical model to predict temperature inside PPM nests based on heat transfer equations and to explain this important temperature excess. A simple model version accurately predicted experimental measurements, confirming that nest temperature is driven mainly by radiation load. Finally, the model showed that nest temperature increases at the same rate as air temperature change. We conclude that some pest insects already live in warm microclimates by building their own sheltering nest. This effect should be considered when studying the impact of climate change on phenology and distribution.

Monitoring and Management of the Pine Processionary Moth in the North-Western Italian Alps

The pine processionary moth (PPM), Thaumetopoea pityocampa (Denis and Schiffermüller, 1775) (Lepidoptera, Notodontidae), is considered one of the main insect defoliators of conifers in Southern Europe and North Africa. The species is oligophagous on pines and cedars in Mediterranean countries. This 6-year investigation (2014–2019), carried out in Aosta Valley (NW Italy), on Pinus sylvestris L. aimed to: (i) Monitor the PPM population with pheromone-baited funnel traps; (ii) assess the infestation index (0–5 classes) according to the degree of defoliation; and (iii) apply control strategies, namely Bacillus thuringiensis var. kurstaki (Btk) and mating disruption (MD). In total, 9618 ha were visually monitored and assigned an infestation index. The percentage of woodland stands that were strongly defoliated by PPM (infestation index ≥ 3) increased progressively between 2015 and 2016, affecting from 8% to 19% of the total area monitored; this area decreased to 16% and 13% in 2017 and 2018, respectively, followed by an abrupt decline to 4% in 2019. Both Btk applications and mating disruption significantly reduced the infestation. Where Btk was applied, the rate of larval mortality ranged from 79.47% to 98.43%; conversely, in the control plots, the larval mortality was, on average, 1.56%. The mean number of PPM males captured in traps was significantly lower in the plots where MD was performed, ranging from 8.36 ± 2.37 to 13.47 ± 4.68. The mean number of males captured in the control plots was, on average, 119.16 ± 12.68. The total number of nests recorded per tree was significantly lower in MD plots, ranging from 0.41 ± 0.05 to 0.94 ± 0.14. In the control plots, there were, on average, 4.37 ± 0.76 nests per tree. As already documented for several defoliating forestry insect pests, both Btk and mating disruption proved effective in controlling PPM infestations, and thus, microbial insecticides should be strongly encouraged and adopted by forest managers.

New Data on the Range Expansion of the Thaumetopoea pityocampa (Lepidoptera: Notodontidae) 'ENA clade' in Greece: The Role of Bacterial Endosymbionts

The pine processionary moth, Thaumetopoea pityocampa (Denis and Schiffermüller), is an important insect in the Mediterranean region, as it defoliates pines and its urticating hairs can cause allergic reactions in humans and animals. Moreover, this species exhibits an interesting genetic structure as recently a distinct East-North African mtDNA lineage ('ENA clade') has been described. This clade has been recently detected in Greek populations where it has currently expanded its range by replacing the 'endemic' T. pityocampa lineages. Here, we report new data on the rapid spread of 'ENA clade' in the Greek island Evoia in only a few years. As the underlying mechanisms of the 'ENA clade' range expansion has not been studied so far, we screened T. pityocampa for an infection with the heritable bacterial endosymbionts Wolbachia (Bacteria: Anaplasmataceae), Cardinium (Bacteria: Bacteroidaceae), Rickettsia (Bacteria: Rickettsiaceae) and Spiroplasma (Bacteria: Spiroplasmataceae). These bacteria can manipulate the reproduction of infected hosts, something that could potentially explain the rapid spread of 'ENA clade' lineage. Therefore, we screened 28 individuals that exhibited T. pityocampa 'ENA clade' and 'endemic' T. pityocampa haplotypes from nine populations scattered all over Greece. None of them was infected with any of the four endosymbionts, suggesting that these bacteria do not cause reproductive manipulations in T. pityocampa lineages and, thus, other factors should be explored in future research efforts.

A novel adhesive trunk trap net for trapping Eucryptorrhynchus brandti (Coleoptera: Curculionidae)

BACKGROUND

Eucryptorrhynchus brandti (Harold) is a destructive wood-boring pest of tree of heaven, Ailanthus altissima, in China. At present, the management of E. brandti relies exclusively on frequent applications of synthetic insecticides. Environmentally friendly alternatives to the use of synthetic insecticides would be beneficial. A trunk trap net (TTN), an adhesive trap (AT), and an adhesive trunk trap net (ATTN) were evaluated in their ability to capture E. brandti.

RESULTS

Significantly greater laboratory weevil recapture rates were found using the ATTN (78%) than using the TTN (8%) and AT (0%). In total, 45% of marked weevils were captured by the ATTN, an eight-fold increase in catch rates using the TTN in mark-release-recapture field trials in 2017. No marked weevils were captured by the AT. Field trials in 2017 and 2018 showed that the ATTN captured six to seven times more wild weevils than using the TTN.

CONCLUSION

Adhesive Trunk Trap nets (ATTNs) were more effective in capturing E. brandti adults than Trunk Trap nets (TTNs). These results support the use of the ATTN as an eco-friendly tool for the integrated management of E. brandti. © 2019 Society of Chemical Industry.

Recent Advances in Management by Pheromones of Thaumetopoea Moths in Urban Parks and Woodland Recreational Areas

Caterpillars of the pine processionary moths, Thaumetopoea complex, cause serious defoliation to Cedrus, Pinus, and Pseudotsuga trees. Thaumetopoea caterpillars also have fine hairs on their abdominal tergites that contain a protein that can severely irritate and cause dermatitis in humans and domestic animals. The control of the T. pityocampa pine processionary moth has become necessary in many European countries because of the sanitary risks that are related to larval urtication and the defoliation threat to pine forests and plantations. New research activities have been aimed at the development of eco-friendly, innovative technologies for Integrated Pest Management (IPM) of these moths, particularly in urban parks and woodland recreational areas. This paper describes the recent advances in the use of pheromones in monitoring, mass trapping, and mating disruption related to management of processionary moths T. hellenica and T. pityocampa. According to the results, the use of pheromones may provide a practical alternative to insecticide sprays, as they can be safe and simple as compared to other control methods.

Efficacy of Trunk Trap Nets and Insecticides Applied Alone and in Combination for Control of Tree-of-heaven Root Weevil Eucryptorrhynchus scrobiculatus in Ailanthus altissima Plantations

In Northern China, the tree-of-heaven root weevil (TRW), Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Curculionidae), is a serious borer pest of Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae) (tree-of-heaven) is an important tree species for landscapes and afforestation. This study evaluates the efficacy of trunk trap nets (TTN), thiacloprid spray (TS), and cypermethrin spray (CS) alone, and in combination with TTN and thiacloprid or cypermethrin spray (TTNTS or TTNCS) for controlling TRW in A. altissima plantations in 2016–2018 in three sites (Haojiaqiao, Wutongshu, and Taojiajuan), which are located near Lingwu city in Ningxia, China. TTN, TTNTS, and TTNCS treatments significantly reduce marked TRW captures (more than 93% with respect to the untreated trees) and wild TRW captures in population monitoring trunk trap nets (MTTN) deployed in stands (more than 55% with respect to the untreated trees). Further field trials demonstrate that these TTN, TTNTS, and TTNCS treatments significantly reduce damage to A. altissima in stands; there are no significant differences between TTN and combination treatments. In addition, significantly more TRW are captured in MTTN within Taojiajuan than within Haojiaqiao or Wutongshu in field trials 2018. There were no significant differences between sites in 2016 and 2017. This study indicates that the TS and CS treatments used had very little to no impact on TRW populations and tree health in the timeframe examined. TTN alone are clearly effective for suppressing populations of TRW and stabilizing A. altissima tree health. This physical control technique, using TTN, could be sufficient to manage TRW on tree-of-heaven with no insecticide.

Novel trunk trap net designs for the control of Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae)

BACKGROUND

Eucryptorrhynchus scrobiculatus is a major pest of tree of heaven, Ailanthus altissima, in China. Damage caused by E. scrobiculatus has increased as beetle populations have expanded. We developed a trunk trap net (TTN) and two modified TTNs, that is, a TTN with a wire ring (TTN-WR) and a TTN with a spongy cushion (TTN-SC), and evaluated their ability to capture E. scrobiculatus in plantations of A. altissima.

RESULTS

We obtained significantly higher laboratory weevil recapture rates using the TTN-WR and TTN-SC (98 and 95.3%, respectively) than using the TTN (65.3%). In total, 84.8 and 85.8% of marked weevils were captured by the TTN-WR and TTN-SC, respectively; 1.52- and 1.54-fold greater than the catch rates using a TTN in mark-release-recapture field trials. Similarly, we captured significantly more wild weevils using the TTN-WR and TTN-SC (2.02- and 2.03-fold more weevils) than using the TTN. Further field trials showed that the TTN-SC treatment significantly reduced densities of weevils and damage to tree of heaven in stands.

CONCLUSION

Our results revealed that the TTN-SC is clearly effective for capturing E. scrobiculatus. TTN-SC may be used as an alternative for E. scrobiculatus management with less or no insecticide. © 2019 Society of Chemical Industry.

Evaluation of Mating Disruption For the Control of Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae) in Suburban Recreational Areas in Italy and Greece

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.

Identification and analysis of the complete mitochondrial genome of Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

The mitochondrial genome (mitogenome) provides important information for phylogenetic analysis and understanding evolutionary origins. Thaumetopoea pityocampa is a forest pest that harms nearly all cedar and pine species. In this study, the T. pityocampa mitochondrial genome was sequenced, assembled, and annotated. The sequence length of the genome was found to be 15,737 bp, containing 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes, and an A + T-rich region compared with the genomes of other lepidopterans. The overall nucleotide composition is: 37.3% T, 40.5% A, 14.6% C, and 7.6% G, demonstrating an AT bias (A + T: 77.8%). Our phylogenetic tree analysis results showed that T. pityocampa and Ochrogaster lunifer were the most similar species, with the closest evolutionary distance. The mitogenome sequence determined in this study will contribute to improved understanding of Notodontidae evolution.

[Variation in Thaumetopoea pityocampa infestation rate of Aleppo pine: Effect on dendrometric parameters in the Djelfa region forests (Saharan Atlas, Algeria)]

The forests of the Saharan Atlas represent the southern edge of the natural range of the Aleppo pine (Pinus halepensis Mill.). These are exposed to climatic stress in relation to drought and attacks of the pine processionary moth (Thaumetopoea pityocampa Schiff., denoted by CP in the French text). The purpose of our work is to study the variation of the infestation rate by the pine processionary moth and its density with climatic factors and dendrometric parameters. The infestation rate (7.82%) by the pine processionary moth and its density (2.74±2.61nests/tree) were lower in our pine forests than in the northern ones. It appeared that the attacks of the moth increase mainly with the number of days of frost and heatwave. The dendrometric parameters were negatively correlated with the moth's density per tree. On the other hand, the latter was positively correlated with the defoliation rate. The results were discussed in a biogeographic framework in the light of the current knowledge of the distribution of the pine processionary moth in the Aleppo pine, in relation with the climatic conditions.

Revisiting the Distribution of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) and T. pityocampa ENA Clade in Greece

In the present work, we sampled individuals of the processionary pine moth, Thaumetopoea pityocampa (Denis and Schiffermüller; Lepidoptera: Notodontidae) from different areas of Greece between 2014 and 2016. These samples were sequenced for a 760-bp long mtDNA COI locus and the haplotypes retrieved clearly showed that the occurrence of T. pityocampa in Greece is being considerably restricted, with only 8 individuals out of the 221 exhibiting T. pityocampa haplotypes and the rest being identified as T. pityocampa ENA clade haplotypes. To that, one haplotype in particular exhibited the highest abundance and broadest geographic distribution, occurring both in mainland and on islands. Our data suggest a rather recent and rapid population expansion of the ENA clade in Greece and a concomitant recent displacement of T. pityocampa. It thus seems that the relation between T. pityocampa and T. pityocampa ENA clade needs to be further and thorough analyzed before the taxonomic status of T. pityocampa ENA clade can be concluded with confidence.