Insecticidal capacity of Cestrum parqui (Solanaceae) leaf extracts on Xanthogaleruca luteola (Coleoptera: Chrysomelidae) adults

Among a series of exotic pests that have been reported in Chile, Xanthogaleruca luteola (Coleoptera: Chrysomelidae), a defoliating insect of elms (Ulmus spp.), is causing important damage in urban trees in central Chile. The insecticidal capacity of water and ethanol extracts obtained from new and mature leaves of Cestrum parqui (Solanaceae) was evaluated at various concentrations on X. luteola adults in the laboratory. Bioassays with a completely randomized design were used to analyze the effects of each extract. Also, the mean lethal concentration (LC50) was determined for both mature leaf states and solvents. A proximal analysis was done to determine the physical and chemical differences between the maturity stages. Proximal analysis of the powder of both leaf stages revealed differences (P < 0.01) in the content of humidity, ashes, lipids, and proteins, but not in the raw fiber content nor the non-nitrogenous extract. On the third day after exposure, the order of decreasing effectiveness (LC50) ofthe insecticide extracts was: new-ethanol (2.5 % w/v), new-water (3.8 % w/v), mature-ethanol (6.7 % w/v) and mature-water (9.2 % w/v). Our results suggest that C. parqui leaf extracts may have potential use as a bioinsecticide in integrated pest management plans for the control of X. luteola adults, however, tests at a larger scale are necessary to confirm our results.

Ovicidal and Physiological Effects of Essential Oils Extracted from Six Medicinal Plants on the Elm Leaf Beetle, Xanthogaleru-Ca Luteola (Mull.)

Plant essential oils may serve as safe alternatives to detrimental synthetic pesticides due to relatively lower side effects on the environment and non-targeted organisms. The current study was conducted to investigate the ovicidal toxicity and physiological disruptions of six medicinal plant essential oils, including Artemisia annua L., Lavandula angustifolia Mill., Origanum vulgare L., Rosmarinus officinalis Spenn., Satureja hortensis L., and Thymus vulgaris L., on elm leaf beetle Xanthogaleruca luteola (Mull.). The LC50 (Lethal Concentration to kill 50% of tested insects) values of 122.8, 287.5, 152.8, 180.6, 315.9, and 1366.2 ppm were recorded for T. vulgaris, L. angustifolia, A. annua, S. hortensis, R. officinalis, and O. vulgare, respectively, 72 h after treatment of 3-day-old eggs of the pest. Significant decreases in the amounts of glucose, protein, and triglyceride macromolecules were also observed after treatment. The application of essential oils derived from T. vulgaris, A. annua, and S. hortensis at 400 ppm revealed 100% ovicidal activity. Accordingly, tested essential oils, particularly the essential oil of T. vulgaris, have been promising potential as biorational insecticides in the management of X. luteola.

Features of the state of the elm trees in the protective plantings of the arid zone of the Lower Volga region

In the Volgograd region, which belongs to low-forest regions, old-growth plantings pre-dominate, in which about 80,0% of the total dendrological composition is accounted for by repre-sentatives of the generic Ulmus complex. In the conditions of urbanization, the pathological pro-cesses and the weakening of woody plants increases. The stable weakened state of the elm trees is typical for squares and roadside plantings (Bsr = 3.28-3.36, respectively). Favorable conditions for maintaining the life optimum of elms are formed in parks, protective forest strips and arbore-tums, where healthy or weakened trees predominate (Bsr = 1,82-1,69-1,87 respectively). Phyl-lophages of different ecological groups are trophically related to the arboreal species of Ulmus. Among leaf-eating pests, Xanthogaleruca luteola Mull is of important economic importance. The pest population varies depending on the ecological conditions of the biotopes and Ulmus species. Keywords: ULMUS, PROTECTIVE FOREST STANDS, CONDITION CATEGORY, MONITORING, ANTHROPOGENIC PRESSURE, PESTS, PEST POPULATION

Pathogenicity of two fungal pathogens on larvae of the elm leaf beetle, Xanthogaleruca luteola Muller (Coleoptera: Chrysomelidae)

Background The elm leaf beetle (ELB), Xanthogaleruca luteola Muller (Coleoptera: Chrysomelidae), is one of the most important insect pests that cause damage and physiological stress for the trees. In the present research, pathogenicity of both entomopathogenic fungi (EPF), Beauveria bassiana and Metarhizium anisopliae on the 1st, 2nd, and 3rd instar larval of ELB at the concentrations of 105, 106, 107, and 108 conidia per ml, using immersion and spray methods and were evaluated. Results The results showed that LC50 of B. bassiana in immersion and spray methods were 3.88 × 102 and 7.52 × 102 conidia/ml, while LC50 of M. anisopliae in mentioned methods were 7.05 × 102 and 11.85 × 102 conidia/ml, respectively. The highest mortality rate in both EPF was observed in the 1st instar larvae that were significantly different than the control treatment. Moreover, the highest and lowest mortality in both EPF, using immersion and spray methods, were observed at the concentrations of 108 and 105 conidia/ml, respectively. Therefore, susceptibility of 1st and 2nd larval instars was more than 1st instar larvae. Based on the findings of the present study, there was no mortality during the first 24 h, while after 2 days, the mortality was recorded and increased over time in case of both pathogens. Accordingly, B. bassiana and M. anisopliae were pathogenic on larvae of ELB. Conclusions The outputs of the study demonstrated that applications of these eco-friendly fungal pathogens with other non-chemical methods are recommended. Of course, under natural conditions, their efficiency may change; thus, more comprehensive studies are necessary.

ПОШИРЕНІСТЬ ГРИЗУЧИХ КОМАХ-ФІЛОФАГІВ У ЛИСТЯНИХ НАСАДЖЕННЯХ м. ХАРКОВА

У вуличних, паркових і лісопаркових насадженнях листяних порід м. Харкова виявлено 108 видів гризучих комах-філофагів, які умовно розподілені на групи: комахи з відкритим способом життя (61 вид) із рядів Hymenoptera (2 види) та Lepidoptera (59 видів); комахи з відкритим способом життя з ряду Coleoptera (33 види); комахи з потаємним способом життя (мінери) (14 видів) із рядів Coleoptera (2 види) та Lepidoptera (12 видів). Видовий склад гризучих комах-філофагів у Лісопарку включає 105 видів, у парках 67 видів, а у вуличних насадженнях – 33 види. Розраховані значення індексу Менхініка (DMn) становлять 10,2; 8,2 та 5,7 у насадженнях Лісопарку, парків і вулиць. Найбільшу подібність комплексів комах-філофагів виявлено у парках і Лісопарку (Cj=0,52 для Coleoptera з відкритим способом життя; Cj =0,59 для Lepidoptera та Hymenoptera з відкритим способом життя і Cj =1 для мінерів). Більшість виявлених видів комах траплялися поодиноко або зрідка. Звичайним видом в усіх типах насаджень був Xanthogaleruca luteola, у Лісопарку – Chrysomela populi та два види роду Clytra, у парках – Tomostethus nigritus, у вуличних і паркових насадженнях – Cameraria ohridella.

Laboratory assay of entomopathogenic nematodes against the elm leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae)

The susceptibility of the elm leaf beetle, Xanthogaleruca luteola Müller (Col.: Chrysomelidae), 3<sup style="text-align: justify;">rd</sup> instar larvae and adults to the entomopathogenic nematodes Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora was determined in laboratory assays. Larval mortality was assessed at 0, 16, 32, 48, 64, 80, 96, and 112 h after exposure of the larvae and adults to six concentrations (0, 100, 200, 300, 400, and 500) of infective juveniles (IJs) per mL. The median lethal concentration (LC₅₀) values for each nematode species against the larvae and adults of X. luteola were 167.59 and 6.73 IJ·mL<sup style="text-align: justify;">–1</sup> for S. feltiae, 218.23 and 204.09 IJ·mL<sup style="text-align: justify;">–1</sup> for S. carpocapsae, and 338.66 and 70.29 IJ·mL<sup style="text-align: justify;">–1</sup> for H. bacteriophora, respectively. Also, the median lethal time (LT₅₀) values for each nematode species against the larvae and adults of X. luteola were 44.51 and 22.23 h for S. feltiae, 50.78 and 36.17 h for S. carpocapsae, and 67.64 and 34.71 h for H. bacteriophora, respectively. The S. feltiae nematode was the most effective species in controlling the larvae and adults of the elm leaf beetle, X. luteola. Based on these and other results, the research could be expanded on the prospects of using entomopathogenic nematodes, especially S. feltiae, in managing of the elm leaf beetle, X. luteola.