INVASIVE PESTS DETECTED IN SOME GREENHOUSES OF EREVAN CITY

The following invasive species: Toxoptera aurantii Boyer de Fonscolombe, Toxoptera citricida Kirkaldy, Macrosiphoniteella sanborni Latr, Toxoptera , Macrosiphoniella Del Guercio), Trialeurodes vaporariorum Westwood (Aleyrodidae West., Trialeurodes Cockerell), Tetranychus viennensis Zacher (Tetranychidae Donn, Tetranychus Dufour), and Cenopalpus mespili Lufour. et Mitrofanov (Tenuipalpidae Sayed, Cenopalpus Pritchard & Baker) were identified during studying of the pest fauna of three greenhouse complexes ("Grig Garden", "Green Paradise" and "Avan") in Yerevan which are specialized on the cultivation of ornamental plants. Insecticide and acaricide resistant lines of Tetranychus viennensis and Macrosiphum rosae were found in two greenhouse complexes.

ИНСЕКТИЦИДНАЯ АКТИВНОСТЬ АЛКИЛПРОИЗВОДНЫХ 5-(П-АМИНОФЕНИЛ)- 1,3,4-ОКСАДИАЗОЛ-2-ТИОНА

Цель. Изучение инсектицидной активности производных 1,3,4-оксадиазолов в отношении сокососущих вредителей садовых культур (Aphis pomi) и декоративных растений (Macrosiphum rosae). Методы и материалы исследования. Материалами для исследований послужили алкилпроизводные 5-(п-Аминофенил)-1,3,4-оксадиазол-2-тиона, формулы которых приведены в тексте статьи, взрослые особи яблоневой тли (Aphis pomi) и розовой тли (Macrosiphum rosae). Методы исследования: первичный скрининг инсектицидной активности изучали методом инкубации в чашках Петри взрослых особей насекомых-вредителей. Насекомых подвергали действию веществ в течение 24 часов. Результаты. Сокососущий вредитель – тля наносит значительный вред растениям, распространяя различные вирусы, поражающие сельскохозяйственные культуры. Для борьбы с сокососущими вредителями необходимы средства химической защиты растений с малой токсичностью для окружающей среды. По результатам скрининга доказано, что биологическая эффективность веществ 2-гексилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (1), 2-октилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (3) и 2-нонилтио-5-(п-Аминофенил)-1,3,4-оксадиазол (4) составляла 98.0%, 97.0% и 99.5% в отношении особи M. rosae. Под воздействием 2-гексилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (1), 2-октилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (3) и 2-нонилтио­-5-(п-Аминофенил)-1,3,4-оксадиазола (4) в дозе 5.0 мг/мл смертность особейA. pomi достигла 99.0%, 83.0% и 90.0%, соответственно. Впервые изучена летальная концентрация (LC50) 2-гексилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (1), 2-гептилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (2), 2-октилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (3), 2-нонилтио-5-(п-Аминофенил)-1,3,4-оксадиазола (4) при контактном действии с насекомым. Заключение. Таким образом, поиск и создание инсектицидов низкой токсичности для окружающей среды, предотвращающие возникновение резистентности на основе алкилпроизводных 5-(п-Аминофенил)-1,3,4-оксадиазол-2-тиона в защите растений является актуальным направлениям. Исследование показало, что 2-гексилтио-5-(п-Аминофенил)-1,3,4-оксадиазол (1), 2-октилтио-5-(п-Аминофенил)-1,3,4-оксадиазол (3) и 2-нонилтио-5-(п-Аминофенил)-1,3,4 оксадиазол (4) в концентрации 0.5 мг/мл сильно токсичны для особей M. rosae и A. pomi. Работа по использованию алкилпроизводных 5-(п-Аминофенил)-1,3,4-оксадиазол-2-тионов в качестве сельскохозяйственных средств защиты будут продолжены.

Changes in Aphid–Plant Interactions under Increased Temperature

Thermal stress in living organisms causes an imbalance between the processes of creating and neutralizing reactive oxygen species (ROS). The work aims to explain changes in the aphid–host plant interaction due to an increase in temperature. Tests were carried out at three constant temperatures (20, 25, or 28 °C). Firstly, changes in development of Macrosiphum rosae were determined. Secondly, the activity of enzymatic markers (superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), β-glucosidase, polyphenol oxidase (PPO), and peroxidase (POD)) in aphid M. rosae tissues and host plant were analyzed at all temperatures. An increase in temperature to 28 °C had a negative effect on the biology of M. rosae by shortening the period of reproduction and longevity, thus reducing the demographic parameters and fecundity. Two stages of the aphid’s defensive response to short-term (24–96 h) and long-term (2 weeks) thermal stress were observed. Aphid defense responses varied considerably with temperature and were highest at 28 °C. In turn, for the plants, which were exposed to both abiotic stress caused by elevated temperature and biotic stress caused by aphid feeding, their enzymatic defense was more effective at 20 °C, when enzyme activities at their highest were observed.

Application of UV-C Irradiation to Rosa x hybrida Plants as a Tool to Minimise Macrosiphum rosae Populations

UV-C irradiation is known to enhance plant resistance against insect pests. In the present study, we evaluated the effects of low doses of UV-C on Macrosiphum rosae infesting greenhouse rose (Rosa x hybrida) plants. The application of 2.5-kJ/m2 UV-C irradiation on rose leaves before infestation induced anti-herbivore resistance and negatively affected the aphid fecundity. No eggs and first instar nymphs were recorded on irradiated leaves, whereas an average of 4.3 and 2.7 eggs and 6.7 and 14 first instars were recorded on vars. “Etoile Brilante” and “Arlen Francis” untreated leaves, respectively. UV-C irradiation reduced the aphid population from naturally infested rose plants by up to 58%. In a greenhouse pot trial (GPT) in 2019, UV-C irradiation minimised the initial aphid population six hours after treatment. UV-C elicited host resistance and, also, helped in aphid repulsion without killing the adult individuals. UV-C did not affect the physiological responses of rose plants. The net CO2 assimilation of the UV-C irradiated plants ranged between 10.55 and 15.21 μmol/m2. sec for “Arlen Francis” and between 10.51 and 13.75 μmol/m2. sec for “Etoile Brilante” plants. These values, with only a few exceptions, were similar to those recorded to the untreated plants.

Diversity of aphid pests on the crops in Kanchanpur district, Nepal

A survey was conducted to explore the aphid pests’ diversity in Kanchanpur district, far-western, Nepal from April 2018 to March 2019. A total of 15 aphid pests were collected and identified, viz. Acyrthosiphon pisum (Harris), Aphis craccivora (Koch), Aphis gossypii (Glover), Aphis fabae (Scopoli), Aphis nerii Boyer de Fonscolombe, Brevicoryne brassicae (Linnaeus), Lipaphis erysmi (Kaltenbach), Macrosiphum euphorbiae (Thomas), Macrosiphum rosae (Linnaeus), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (Linnaeus), Rhopalosiphum rufiadominale (Sasaki), Uroleucon compositae (Theobald), and the guava aphid. Exploration of aphid pests showed that they caused serious damages to agricultural crops by attacking different parts of plants.

PHOTOTOXICITY OF α-TERTHIENYL AND PSORALENE INROSE AND MUSTARD APHIDS (MACROSIPHUM ROSAE & LIPAPHIS ERYSIMI) IN DOON VALLEY

Climate change has an impact on agriculture and insect pests that affect the crop production. Aphid pests occur throughout the temperate region of the world andcause direct damage by sucking plants sap which affects growth and yield of the crops. Species of aphids are diverse and ubiquitous but their importance among crop differs.Ultraviolet radiation (UVR) is an electromagnetic radiation and constitutes about 10% of the total light output of sunlight. Ultraviolet-B coming due to ozone depletion is the most photo chemically reactive wavelength of solar radiation and important stressor to organisms particularly in their early stages of life and affect ecosystem. Psoralene and alpha- terthienyl are naturally occurring plant metabolites found in many crops and become photo reactive in presence of solar ultraviolet- B radiation. Measurement of solar ultraviolet radiation (UV-B and UV-E) was performed in Garhwalregion of Uttarakhand. Morphological, behavioural changes, mortality rate and glutathione contents were observed in mustard and roseaphids after ultraviolet-B irradiation with psoralene and α-terthienyl photo sensitizers. UV-B and UV-E radiation showed seasonal, diurnal and altitudinal variations. α- terthienyland psoralenewith ultraviolet-B radiation showed stunted growth, morphological changes, low reproduction and high mortality up to 26% in aphids. Reduction in glutathione (GSH) level in aphids was also observed after UV- B and photosensitizersexposure.Enhanced UV-B was found more toxic with photosensitizers andthus, can be used as natural insecticide. Dose, intensity and species dependent changes in toxicity of psoralene and α- terthienyl were observed in aphids. Resultsindicate that UV-B radiation with photosensitizers has toxic effect on aphids population, dispersal and diversity. Psoralene was found more toxic than α- terthienyl in aphids. Mustard aphid (Lipaphis erysimi) was found more sensitive than rose aphid (Macrosiphum rosae).