Preliminary data on attractiveness of phenylacetaldehyde-based lures on economically important plant bug pests (Hemiptera: Miridae)

Several plant bug species (Miridae) are important pests of crops and vegetables, thus monitoring them is of essential importance for effective pest control. During the current, preliminary study synthetic plant volatile combinations were tested in field conditions in Hungary in alfalfa fields. Beside semiochemical baited traps, sweep-netting was also performed. In the experiments three plant bug species were found in higher numbers: Adelphocoris lineolatus, Lygus rugulipennis and L. pratensis. As a novel, interesting finding L. pratensis was attracted to phenylacetaldehyde baited traps. For all species, both males and females were trapped in all combinations. Sweep-netting and semiochemical baited traps showed different efficacy in case of the three species, as sweep-netting catches were highly biased for A. lineolatus, which indicates the higher efficacy of this method as compared to the tested semiochemical-baited traps. On the other hand, semiochemical baited showed better performance for L. rugulipennis and L. pratensis. For these species none of the tested combinations performed better than phenylacetaldehyde baited traps. The potential implication of results in view of monitoring are discussed.

Фітосанітарний моніторинг шкідливої ентомофауни посівів сої в умовах рисових зрошувальних систем

Мета. Визначення видового складу ентомофагівта виявлення домінуючих шкідників посівів сої у корот-коротаційних рисових сівозмінах Південного СтепуУкраїни. Методи. Польовий, лабораторний, розрахунко-во-порівняльний і статистичний. Результати. Отриманоінформацію щодо видового складу шкідників у посівахсої та встановлено їх домінуючі види у короткоротаційнихрисових сівозмінах: метелик лучний (Margaritia sticticalis L.),сонцевик будяковий, або чортополохівка (Vanessacardui L.), клоп трав’яний (Lygus rugulipennis Popp.), клоплюцерновий (Adelphocoris lineolatus Goeze.), щитниклюцерновий (Piezodorus lituratus F.), трипс тютюновий(Thrips tabaci Lind.), совка-гамма (Autographa gamma L.),совка люцернова (Chloridea viriplaca Hfn.), коник зелений(Tettigonia viridissima L.), прус італійський (Calliptamusitalicus L.), попелиця велика злакова (Sitobion avenae F.),кліщ павутинний звичайний (Tetranychus urticae Koch.),сарана мароканська (Dociostaurus maroccanus Thunb.),цикадка шестикрапкова (Macrosteles laevis Kib.); цика-дка смугаста (Psammotettix striatus L.), елія носата (Aeliarostrata Bsh.), довгоносик смугастий бульбочковий(Sitona lineatus L.), довгоносик сірий щетинистий (Sitonacrinitus Hfn.), совка бавовникова (Helicoverpa armigera),вогнівка акацієва (Etiella zinckenella Tr.). Висновки.Кількість виявлених видів шкідників у посівах сої становила: ряд лускокрилих (Lepidoptera) – 38,0%; ака-риформні кліщі (Acariformes) 22,0%, бахромчастокрилі(Thysanoptera) – 17,0%, напівтвердокрилі (Hemiptera) –10,0%, представники ряду рівнокрилих (Homoptera) – 5,0%,прямокрилих (Orthoptera) – 5,0% та твердокрилих(Coleoptera) – 3,0%. Домінуючими видами в умовах рисо-вих чеків були: метелик лучний (Pyrausta sticticalis L.) –15 екз./м2, трипс тютюновий (цибулевий) (Thripstabaci Lind.) – 50 екз./м2, звичайний павутинний кліщ(Tetranychus urticae Koch.) – 47 екз./рослину, сонце-вик будяковий (чортополохівка) (Vanessa cardui L.) –від 2 до 5 екз./м2.

OBP14 (Odorant-Binding Protein) Sensing in Adelphocoris lineolatus Based on Peptide Nucleic Acid and Graphene Oxide

OBPs play a crucial role in the recognition of ligands and are involved in the initial steps of semiochemical perception. The diverse expression of OBP genes allows them to participate in different physiological functions in insects. In contrast to classic OBPs with typical olfactory roles in A. lineolatus, the physiological functions of Plus-C OBPs remain largely unknown. In addition, detection of the expression of insect OBP genes by conventional methods is difficult in vitro. Here, we focused on AlinOBP14, a Plus-C OBP from A. lineolatus, and we developed a PNA-GO-based mRNA biosensor to detect the expression of AlinOBP14. The results demonstrated that AlinOBP14 plays dual roles in A. lineolatus. The AlinOBP14 is expressed beneath the epidermis of the vertex and gena in heads of A. lineolatus, and it functions as a carrier for three terpenoids, while AlinOBP14 is also expressed in the peripheral antennal lobe and functions as a carrier for endogenous compounds such as precursors for juvenile hormone (JH) and JHⅢ. Our investigation provides a new method to detect the expression of OBP genes in insects, and the technique will facilitate the use of these genes as potential targets for novel insect behavioral regulation strategies against the pest.

Sex Pheromone of the Alfalfa Plant Bug, Adelphocoris lineolatus: Pheromone Composition and Antagonistic Effect of 1-Hexanol (Hemiptera: Miridae)

The sex pheromone composition of alfalfa plant bugs, Adelphocoris lineolatus (Goeze), from Central Europe was investigated to test the hypothesis that insect species across a wide geographical area can vary in pheromone composition. Potential interactions between the pheromone and a known attractant, (E)-cinnamaldehyde, were also assessed. Coupled gas chromatography-electroantennography (GC-EAG) using male antennae and volatile extracts collected from females, previously shown to attract males in field experiments, revealed the presence of three physiologically active compounds. These were identified by coupled GC/mass spectrometry (GC/MS) and peak enhancement as hexyl butyrate, (E)-2-hexenyl butyrate and (E)-4-oxo-2-hexenal. A ternary blend of these compounds in a 5.4:9.0:1.0 ratio attracted male A. lineolatus in field trials in Hungary. Omission of either (E)-2-hexenyl-butyrate or (E)-4-oxo-2-hexenal from the ternary blend or substitution of (E)-4-oxo-2-hexenal by (E)-2-hexenal resulted in loss of activity. These results indicate that this Central European population is similar in pheromone composition to that previously reported for an East Asian population. Interestingly, another EAG-active compound, 1-hexanol, was also present in female extract. When 1-hexanol was tested in combination with the ternary pheromone blend, male catches were reduced. This compound showed a dose-response effect with small doses showing a strong behavioral effect, suggesting that 1-hexanol may act as a sex pheromone antagonist in A. lineolatus. Furthermore, when (E)-cinnamaldehyde was field tested in combination with the sex pheromone, there was no increase in male catch, but the combination attracted both males and females. Prospects for practical application are discussed.

Does Harvesting Affect the Spatio-Temporal Signature of Pests and Natural Enemies in Alfalfa Fields?

Determining the spatio-temporal distribution and association of pests and natural enemies would be useful for implementing biological control of pests and could also be used in site-specific pest management. In this study, the spatio-temporal distribution and association of aphids, plant bugs, and natural enemies were assessed in alfalfa fields using geo-statistics and spatial analysis by distance indices (SADIE). Additionally, the effect of alfalfa hay-harvesting on the spatial and temporal distribution of these insects was investigated for the first time. Geostatistical analysis indicated that the degree of dependence (DD) was ≥75% for 11 out of 39, 9 out of 35, 3 out of 12, 10 out of 29, and 2 out of 20 datasets for pea aphid Acyrthosiphon pisum, spotted alfalfa aphid Therioaphis maculata, cowpea aphid Aphis craccivora, alfalfa plant bug Adelphocoris lineolatus, and tarnished plant bug Lygus rugulipennis, respectively. The results also indicated that DD was ≥75% in 7 out of 45, 18 out of 45, and 3 out of 20 datasets for Coccinella septempunctata, Hippodamia variegata, and Pterostichus melanarius, respectively. Harvesting decreased the aggregation of the ladybirds, which resulted in a decrease in the index of aggregation. The geo-statistics results were confirmed by SADIE in 75% of datasets. These results can be used in biological control and site-specific management of aphids and plant bugs in alfalfa fields.