Pine Processionary Moth Thaumetopoea Wilkinsoni Research Articles

Efficacy of Beauveria bassiana and Metarhizium brunneum isolates against the pine processionary moth, Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera: Notodontidae)

BackgroundThe pine processionary moth Thaumetopoea wilkinsoni Tams, 1926 (Lepidoptera: Notodontidae), causes severe skin reactions to animals and humans. The insect also destroys pine ecosystems by feeding on pine leaves at its larval stage. Instead of chemical control, eco-friendly biological control methods should be preferred to combat this species.ResultsThe purpose of this study was to evaluate the efficacy of Beauveria bassiana isolate (GOPT-331) and Metarhizium brunneum isolates (ORP-13 and ORP-18) against the second and fourth larval instars of T. wilkinsoni under laboratory conditions. T. wilkinsoni eggs were collected from pine trees at Ondokuz Mayıs University in Samsun, Turkey, in 2021, and the second and fourth larval instars were used for the experiment. Two milliliters of a spray of the three fungal isolates was applied to the larvae for each concentration (1 × 105–1 × 108 conidia ml−1). The mortality rates of GOPT-331, ORP-13, and ORP-18 were changed between 91.1 and 100% for the second-instar larvae and between 86.6 and 97.7% for the fourth-instar larvae at 1 × 108 conidia ml−1. The ORP-13 isolate showed the lowest LC50 values.ConclusionIn conclusion, it is suggested that all the three isolates were virulent to T. wilkinsoni and can be used for biological control of this species. The promising results from the study were obtained from trials conducted under controlled laboratory conditions, and it will be critical to explore the potential of these promising entomopathogenic fungi in field conditions.

Efficacy of Diptera-targeted Bacillus thuringiensis var. israelensis against the pine processionary moth, Thaumetopoea wilkinsoni (Lepidoptera: Notodontidae)

The pine processionary moth Thaumetopoea wilkinsoni (Tams, 1926) (Lepidoptera: Notodontidae) is one of the most harmful species that destroys to the pine ecosystem and causes severe skin reactions in humans and animals due to its urticating setae. The aim of this study is to evaluate the efficacy of the hypertoxic strain of Diptera-targeted Bacillus thuringiensis var. israelensis against the second instar larvae of T. wilkinsoni under laboratory conditions. A total of 5 mL of bacterial strain spray was applied to 30 larvae at concentrations of 101, 103, 105, 107, and 109 cfu/mL. As a result of the study, it was determined that the survival rate of the larvae exposed to Bti pHTppk decreased with increasing bacterial concentration, and the survival rate of the 109 cfu/mL concentration group was 33.3%. It is suggested that Bti pHTppk is virulent for T. wilkinsoni larvae and that this strain can be used in the biological control of this species.

Egg laying patterns and structure of egg-batches of pine processionary moth Thaumetopoea wilkinsoni in Isparta pine forests

Bu calismada, Thaumetopoea wilkinsoni Tams (Lepidoptera: Notodontidae)’nin yumurta paketlerinin yapisi, tirtil cikisi, parazitlenme oranlari ile yumurta parazitoidleri ve bocegin bazi yumurta birakma davranislari arastirilmistir. Isparta’da 16 cam ormanindan bu bocegin 654 adet yumurta kocani toplanmistir. Kocan basina ortalama yumurta sayisi 221.2, tirtil cikis orani % 80.0 ve parazitlenme orani % 13.8 olmustur. Alt, orta ve ust yukselti basamaklarinda ortalama yumurta sayisi sirasiyla 208.1, 223.3 ve 226.7, tirtil cikis orani % 73.3, % 82.6, % 85.3 ve parazitlenme orani da %

Seasonal history, plant interactions and egg parasitism of the variegated caper bugStenozygum coloratumKlug (Heteroptera: Pentatomidae)

The variegated caper bug Stenozygum coloratum Klug is common in the Middle East, where it is a minor agricultural pest. Recently, it was found that S. coloratum is an alternative host for the egg parasitoid Ooencyrtus pityocampae Mercet, an important natural enemy of the pine processionary moth Thaumetopoea wilkinsoni Tams, a major pest of pines. This discovery, coupled with the general lack of knowledge of S. coloratum, prompted the present study, which focused on seasonal activity of S. coloratum in Israeli pine forests, bidirectional interactions between the bug and its host the caper plant Capparis spp., and parasitism of its eggs. Stenozygum coloratum activity lasted mainly from May to October, and was followed by an adult winter diapause. Individuals formed large aggregations, causing early withering of plants and a shortening their annual growth periods. Reproductive activity peaked in August and ended in September. Egg parasitism rates increased throughout this period. Several Ooencyrtus spp., including known natural enemies of various pests, parasitized the eggs of S. coloratum and other associated pentatomids found on the caper plants. Thus, capers probably serve as a refuge for these potentially important egg parasitoids. The potential of caper plants and their fauna for biological control programmes is discussed.

Toxicity of native Bacillus thuringiensis isolates on the larval stages of pine processionary moth Thaumetopoea wilkinsoni at different temperatures

Pine processionary moth, Thaumetopoea wilkinsoni Tams, is an important defoliating lepidopteran pest of pine trees. The aim of this study was to determine the required spore-crystal concentration of local Bacillus thuringiensis (Bt) isolates, optimal ambient temperature, and larval stage to control this troublesome forest pest. The susceptibility of T. wilkinsoni larvae decreased with older stage and lower temperatures. The optimum temperature was found to be 15 °C or higher for the control of early larval stages. At the highest spore-crystal concentration (500 µg g^{-1}), the most effective isolate (SY49.1) caused 83% mortality for the second-stage larvae at 5 °C. However, an approximately 4-fold decrease in mortalities was observed in late-stage larvae for all isolates examined at this temperature. Nevertheless, other Bt isolates, excluding SY27.3, caused nearly complete mortality at 25 °C for early-stage larvae. Considering the distribution of seasonal temperature, Bt products should be applied at the highest ambient temperature to earlier stages for efficient control. We propose that local Bt isolates SY27.1, SY49.1, and SY62.1 could be used to develop environmentally safe bioinsecticides to control this important pest species. These results indicate that larval stage and environmental temperature should be taken into consideration for efficient control of T. wilkinsoni using the spore-crystal mixture of Bacillus thuringiensis isolates.

Efficacy and molecular studies of a Lebanese isolate of Beauveria for control of Thaumetopoea wilkinsoni (Lepidoptera: Thaumetopoeidae)

A Lebanese isolate of a Beauveria species originally isolated from a hymenopterous insect pest was found to be very effective against the pine processionary moth Thaumetopoea wilkinsoni. In laboratory bioassays, high mortality rates of the five larval stages were attained with spore concentrations of about 5000–50,000 spores/larva. The efficacy of kill on the first three larval stages was similar to the growth regulator diflubenzuron, but it was significantly higher on the fourth and fifth larval stages. Sequences of the DNA lyase gene and the EF-1α gene were used for molecular characterisation of this Beauveria isolate. The DNA lyase gene showed more polymorphism than the previously reported ITS region and EF-1α gene. This constitutes the first report on the possibility of using the DNA lyase gene as a molecular tool in fungal taxonomy.

Environmental persistence ofBacillus thuringiensis products tested under natural conditions againstThaumetopoea wilkinsoni

Information on persistence ofBacillus thuringiensis (Bt) is needed to improve the microbial pest management programs against the pine processionary mothThaumetopoea wilkinsoni in pine forests in Israel. The persistence of the microbe under natural conditions of rain and sunlight was evaluated and is documented here for the first time. Pine saplings were sprayed with three commercialBt products, Foray 48B, Delfin WG and Dipel DF, all used at 32,000 IU mg−1 in a formulation with 1% (w/v) of condensed milk. In experiments conducted in November and December of 2004, the saplings were either exposed to rain and sunlight or were sheltered to avoid these environmental factors. The lowest rainfall recorded in the 8-day experiments was 16.5 mm (test 2) and the heaviest was 71.1 mm (test 1). Solar irradiation ranged from 9.4 to 10.9 MJ m−2. The minimum temperature was close to 10°C and the maximum was less than 23°C. Needles of the treated saplings and their controls were sampled after 0, 1, 5 and 8 days, and were fed to 1st or 2nd instar larvae. Dipel DF persisted better than Delfin WG and still retained its initial activity of 80–100% mortality on day 8 at low rainfall (test 2). Dripping ofBt from upper to lower branches was quantified with the larval bioassays. The milk formulation proved to be an effective rain-fasting adjuvant.

Phylogeography of the pine processionary mothThaumetopoea wilkinsoniin the Near East

Phylogeographic structure of the eastern pine processionary moth Thaumetopoea wilkinsoni was explored in this study by means of nested clade phylogeographic analyses of COI and COII sequences of mitochondrial DNA and Bayesian estimates of divergence times. Intraspecific relationships were inferred and hypotheses tested to understand historical spread patterns and spatial distribution of genetic variation. Analyses revealed that all T. wilkinsoni sequences were structured in three clades, which were associated with two major biogeographic events, the colonization of the island of Cyprus and the separation of southwestern and southeastern Anatolia during the Pleistocene. Genetic variation in populations of T. wilkinsoni was also investigated using amplified fragment length polymorphisms and four microsatellite loci. Contrasting nuclear with mitochondrial data revealed recurrent gene flow between Cyprus and the mainland, related to the long-distance male dispersal. In addition, a reduction in genetic variability was observed at both mitochondrial and nuclear markers at the expanding boundary of the range, consistent with a recent origin of these populations, founded by few individuals expanding from nearby localities. In contrast, several populations fixed for one single mitochondrial haplotype showed no reduction in nuclear variability, a pattern that can be explained by recurrent male gene flow or selective sweeps at the mitochondrial level. The use of both mitochondrial and nuclear markers was essential in understanding the spread patterns and the population genetic structure of T. wilkinsoni, and is recommended to study colonizing species characterized by sex-biased dispersal.

Effectiveness of a naturally derived insecticide, spinosad, against the pine processionary moth Thaumetopoea wilkinsoni Tams (Lepidoptera: Thaumetopoeidae) under laboratory conditions

The pine processionary moth Thaumetopoea wilkinsoni Tams is a serious pest on pine trees in southwestern Turkey. The efficacy of a naturally derived insecticide, spinosad, on fourth-fifth instar larvae of T. wilkinsoni was studied under laboratory conditions. The product exhibited strong larvicidal activity and at doses above 5 mg litre(-1) caused > 90% mortality in the fourth-fifth larval stages of the species after 72 h. At 72 h the LD50 and LD90 values were 3.26 and 5.69 mg litre(-1) respectively. The results showed that spinosad is highly effective on T. wilkinsoni larvae.