Search

The green shield bug,Palomena prasina(Hemiptera: Pentatomidae), is a pest of deciduous trees and shrubs throughout Turkey and is found in a large variety of habitats, including gardens. We investigated the facultative cultivable bacterial flora of 10 healthy and 5 dead green shield bugs, collected from the vicinity of Trabzon, Turkey, and tested them for insecticidal activity. Based on the conventional and molecular tests, 12 different bacteria were isolated and identified asCurtobacteriumsp.,Rhodococcussp.,Arthrobacter nicotinovorans,Arthrobacter oxydans,Agrococcus jejuensis,Pseudomonas poae,Raoultella terrigena,Serratiasp.,Lysinibacillus sphaericus,Stenotrophomonas rhizophila,Bacillus thuringiensisandMicrobacterium oxydans. Mortalities due to the application of 0.5 mL ofL. sphaericus,B. thuringiensisandR. terrigenaat a density of OD6001.89 were 60%, 70% and 60%, respectively, on adultP. prasina. This indicates that facultative cultivable bacterial flora isolated fromP. prasinahave potential for microbial control of this pest. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the characterisation and toxicity of Bacillus thuringiensis Berliner (Bt) strains in hazelnut pests and fields in the eastern Black Sea region of Turkey from 2002 to 2006. The study collected larvae and adults of Agelatica alni L. and Amphimallion solstitiale L., soil samples, and conducted microscopic examination. The results of the study revealed that variety of Bt isolates were dominant in hazelnut pests and hazelnut fields.

The pine processionary moth Thaumetopoea pityocampa Den. and Schiff. (Lep., Thaumetopoeidae) is one of the most harmful insect pests for pine species in Mediterranean countries including Turkey. Two Bacillus thuringiensis isolates obtained from T. pityocampa were identified and characterized in terms of crystal shape using electron microscopy, SDS-PAGE analysis, cry gene contents, H-serotype and insecticidal activity. Examination by a scanning electron microscope showed that Tp6 and Tp14 isolates have flat square and bipyramidal crystal shapes, respectively. PCR analysis showed that Tp6 contains cry3 gene and Tp14 isolate contains cry1 and cry2 genes. On the other hand, the presence of Cry3 and Cry1 proteins were confirmed by observation of approximately 65- and 130-kDa proteins by SDS-PAGE in Tp6 and Tp14 isolates, respectively. According to H-serotype results, these isolates were identified as Bacillus thuringiensis ssp. morrisoni (H8a8b). Toxicity tests were performed against six insect species belonging to Lepidoptera and Coleoptera. The highest insecticidal activity was 100% for Tp6 isolate on larvae of Agelastica alni and Leptinotarsa decemlineata and 100% for Tp14 isolate on larvae of Malacosoma neustria. Our results indicate that isolates Tp6 and Tp14 may be valuable biological control agents for various coleopteran and lepidopteran pests. [ABSTRACT FROM AUTHOR]

In this study, we have isolated and identified 5 bacterial isolates from European shot-hole borer, Xyleborus dispar (Coleoptera: Scolytidae), an important pest of hazelnut. After various morphological, physiological, biochemical and molecular characteristics were determined in detail, bacterial isolates were identified as Pseudomonas fluorescens (Xd1), Bacillus megaterium (Xd2), Bacillus thuringiensis (Xd3), Pseudomonas rhizosphaerae (Xd4) and Pantoea cedenensis (Xd5). Especially, the B. thuringiensis strain was identified in more detail as Bacillus thuringiensis subsp. tenebrionis (H8ab). The insecticidal activities were determined against the larvae of Agelastica alni L. (Col.: Chrysomelidae), Amphimallon solstitiale L. (Col.: Scarabaeidae), Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae), and Melolontha melolontha L. (Col.: Scarabaeidae) larvae at 1.8×109 CFU/ml dose, within five days. The highest insecticidal activities are 100, 100, 80 and 100% for Bacillus thuringiensis subsp. tenebrionis (Xd3) on A. alni, A. solstitiale, L. decemlineata, and M. melolontha larvae, respectively. Our results indicate that especially B. thuringiensis subsp. tenebrionis (Xd3) may be valuable as a microbial control agent for coleopteran pests, respectively. [ABSTRACT FROM AUTHOR]

Insect adipokinetic hormones (AKHs) are neuropeptides with a wide range of actions, including the control of insect energy metabolism. These hormones are also known to be involved in the insect defence system against toxins and pathogens. In this study, our aim was to demonstrate whether the application of external AKHs significantly enhances the efficacy of the entomopathogenic fungus Isaria fumosorosea in a model species (firebug Pyrrhocoris apterus) and pest species (Egyptian cotton leafworm Spodoptera littoralis and pea aphid Acyrthosiphon pisum). It was found that the co-application of Isaria with AKHs significantly enhanced insect mortality in comparison to the application of Isaria alone. The mode of action probably involves an increase in metabolism that is caused by AKHs (evidenced by the production of carbon dioxide), which accelerates the turnover of Isaria toxins produced into the infected insects. However, several species-specific differences probably exist. Intoxication by Isaria elicited the stimulation of Akh gene expression and synthesis of AKHs. Therefore, all interactions between Isaria and AKH actions as well as their impact on insect physiology from a theoretical and practical point of view need to be discussed further. [ABSTRACT FROM AUTHOR]

The genus Haritalodes Warren, 1890 is represented by 12 species worldwide except in the Nearctic and Neotropical regions. Haritalodes derogata (Fabricius, 1775), commonly known as the cotton leaf roller moth, is the most widely distributed species of the genus and is common in the West Palaearctic Region. This species is one of the most serious pests of Malvaceae. The larvae primarily feed on the leaves, and severe population levels may lead to significant yield loss in the primary host, cotton. In a survey in 2023, the shrubs of the Hibiscus sp. were found to be infested by a group of larvae with a very dense population feeding on the leaves in Trabzon Province, Türkiye. The larvae were reared for pupation and adult emergence. Morphological identification according to male and female genitalia as well as sequencing of the mitochondrial cytochrome oxidase region I (COI) from larvae and adults revealed that the species is H. derogata. This is the first report of the genus Haritalodes and Haritalodes derogata in Türkiye.

A novel bioactive molecule produced by Bacillus thuringiensis subsp. kurstaki Bn1 (Bt-Bn1), isolated from a common pest of hazelnut, Balaninus nucum L. (Coleoptera: Curculionidae), was determined, purified, and characterized in this study. The Bt-Bn1 strain was investigated for antibacterial activity with an agar spot assay and well diffusion assay against B. cereus, B. weinhenstephenensis, L. monocytogenes, P. savastanoi, P. syringae, P. lemoignei, and many other B. thuringiensis strains. The production of bioactive molecule was determined at the early logarithmic phase in the growth cycle of strain Bt-Bn1 and its production continued until the beginning of the stationary phase. The mode of action of this molecule displayed bacteriocidal or bacteriolytic effect depending on the concentration. The bioactive molecule was purified 78-fold from the bacteria supernatant with ammonium sulfate precipitation, dialysis, ultrafiltration, gel filtration chromatography, and HPLC, respectively. The molecular mass of this molecule was estimated via SDS-PAGE and confirmed by the ESI-TOFMS as 3,139 Da. The bioactive molecule was also determined to be a heat-stable, pH-stable (range 6-8), and proteinase K sensitive antibacterial peptide, similar to bacteriocins. Based on all characteristics determined in this study, the purified bacteriocin was named as thuricin Bn1 because of the similarities to the previously identified thuricin-like bacteriocin produced by the various B. thuringiensis strains. Plasmid elution studies showed that gene responsible for the production of thuricin Bn1 is located on the chromosome of Bt-Bn1. Therefore, it is a novel bacteriocin and the first recorded one produced by an insect originated bacterium. It has potential usage for the control of many different pathogenic and spoilage bacteria in the food industry, agriculture, and various other areas.

In order to detect and identify the most toxic Bacillus thuringiensis strains against pests, we isolated a B. thuringiensis strain (Bn1) from Balaninus nucum (Coleoptera: Curculionidae), the most damaging hazelnut pest. Bn1 was characterized via morphological, biochemical, and molecular techniques. The isolate was serotyped, and the results showed that Bn1 was the B. thuringiensis serovar, kurstaki (H3abc). The scanning electron microscopy indicated that Bn1 has crystals with cubic and bipyramidal shapes. The Polymerase Chain Reactions (PCRs) revealed the presence of the cry1 and cry2 genes. The presence of Cry1 and Cry2 proteins in the Bn1 isolate was confirmed via SDS-PAGE, at approximately 130 kDa and 65 kDa, respectively. The bioassays conducted to determine the insecticidal activity of the Bn1 isolate were conducted with four distinct insects, using spore-crystal mixtures. We noted that Bn1 has higher toxicity as compared with the standard B. thuringiensis subsp. kurstaki (HD-1). The highest observed mortality was 90% against Malacosoma neustria and Lymantria dispar larvae. Our results show that the B. thuringiensis isolate (Bn1) may prove valuable as a significant microbial control agent against lepidopteran pests.

Studying the bacteria of hazardous insects allows the opportunity to find potentially better biological control agents. Therefore, in this study, bacteria from summer chafer (Amphimallon solstitiale L., Coleoptera: Scarabaeidae) we isolated and identified the insecticidal effects of bacteria isolated from A. solstitiale and Melolontha melolontha L. (common cockchafer, Coleoptera: Scarabaeidae) and the mixtures of these bacterial isolates were investigated on A. solstitiale larvae. Crystals from Bacillus sp. isolated from M. melolontha were also purified, and tested against the second and third-stage larvae of A. solstitiale. The bacterial isolates of A. solstitiale were identified as Pseudomonas sp., Pseudomonas sp., Bacillus cereus and Micrococcus luteus, based on their morphology, spore formation, nutritional features, and physiological and biochemical characteristics. The insecticidal effects of the bacterial isolates determined on the larvae of A. solstitiale were 90% with B. cereus isolated from A. solstitiale, and 75% with B. cereus, B. sphaericus and B. thuringiensis isolated from M. melolontha within ten days. The highest insecticidal effects of the mixed infections on the larvae of A. solstitiale were 100% both with B. cereus+B. sphaericus and with B. cereus+B. thuringiensis. In the crystal protein bioassays, the highest insecticidal effect was 65% with crystals of B. thuringiensis and B. sphaericus isolated from M. melolontha within seven days. Finally, our results showed that the mixed infections could be utilized as microbial control agents, as they have a 100% insecticidal effect on the larvae of A. solstitiale.

A local isolate of Bacillus thuringiensis Mm2 had insecticidal activity against the larvae of Melolontha melolontha, Agelastica alni, Leptinotarsa decemlineata and Amphimallon solstitiale and produced a 65 kDa protein. SDS-PAGE profile of B. thuringiensis Mm2 was compared with those of 29 different Cry3Aa producers which verified Cry3Aa biosynthesis by the isolate. The cry3Aa gene of Mm2 was cloned, sequenced and the deduced amino acid sequence was compared with the cry3Aa sequences of ten different quaternary ranks. Its identity to these sequences ranged between 97.4% and 99.2%. The gene was next cloned into E. coli-Bacillus shuttle vector pNW33N and expressed at a low level in B. subtilis 168.