Physiological and oxidative stress response of carrot (Daucus carota L.) to jumping plant-louse Bactericera trigonica Hodkinson (Hemiptera: Psylloidea) infestation.

BACKGROUND: Carrot is an important vegetable crop grown worldwide. The major economic problem in carrot cultivation is yellow disease caused by Bactericera trigonica, which induces biotic stress and has the greatest impact on crop productivity. Comprehensive studies on the mechanism of carrot defense response to biotic stress caused by B. trigonica infestation have yet to be conducted. METHODS: The changes in photosynthetic pigments, proline, TPC, H2O2 and MDA content, DPPH radical scavenging ability, and antioxidant enzyme activity of SOD, CAT, and POX in carrot leaves in response to insect sex (female and male), rapid response (during the first six hours), and long-term response to B. trigonica infestation were evaluated. RESULTS: The results of our study strongly suggest that B. trigonica infestation causes significant changes in primary and secondary metabolism and oxidative status of carrot leaves. Photosynthetic pigment content, TPC, and DPPH and CAT activities were significantly reduced in carrot leaves in response to insect infestation. On the other hand, proline, H2O2 content, and the activity of the antioxidant enzymes superoxide dismutase and peroxidase were increased in carrot leaves after B. trigonica infestation. The results indicate that B. trigonica attenuates and delays the oxidative stress responses of carrot, allowing long-term feeding without visible changes in the plant. Carrot responded to long-term B. trigonica infestation with an increase in SOD and POX activity, suggesting that these enzymes may play a key role in plant defense mechanisms. CONCLUSIONS: This is the first comprehensive study strongly suggesting that B. trigonica infestation causes significant changes in primary and secondary metabolism and an attenuated ROS defense response in carrot leaves that enables long-term insect feeding. The information provides new insights into the mechanisms of carrot protection against B. trigonica infestation.

Parasitoids of jumping plant-lice (Psylloidea, Hemiptera) from the family Encyrtidae (Hymenoptera, Chalcidoidea) in Serbia.

The aim of this research was to study the diversity of jumping plant-lice parasitoids and to investigate their potential in biological control applicable to cultivated and ornamental plants. Thirteen species from six genera of encyrtid wasps (Hymenoptera, Chalcidoidea, Encyrtidae) were reared from 24 species of jumping plant-lice (Hemiptera, Psylloidea) in Serbia. A total of 689 encyrtid wasps were collected since 2003 from 51 localities, reared from hosts. The richest genera are Psyllaephagus with four species (P. belanensis (Hoffer), P. fulvipes Erdös, P. procerus Mercet and Psyllaephagus sp.) and Syrphophagus with three species (S. aphidivorus (Mayr), S. taeniatus (Förster) and S. ariantes (Walker)). The most common species, comprising about half of the reared specimens, is Prionomitus mitratus (Dalman). Eight species are new to Serbia: Microterys annulatus (Erdös, 1957), Prionomitus tiliaris (Dalman), Psyllaephagus belanensis, P. fulvipes, P. procerus, Sectiliclava cleone (Walker), Syrphophagus ariantes and Trechnites flavipes (Mercet). Psyllaephagus fulvipes was reared from the nymphs of Craspedolepta conspersa (Löw), the only known host of this species so far. In the present study, 27 new host associations were found.

True bugs (Hemiptera, Heteroptera) as psyllid predators (Hemiptera, Psylloidea).

Data on natural enemies of psyllids are rare and can usually be found in papers about economically significant species. During an investigation of psyllid fauna in Serbia, natural enemies were investigated, too. True bugs were the most numerous among them. From 28 psyllid species, 21 species of true bugs from families Anthocoridae and Miridae were reared. Seven species of Anthocoridae were identified: Anthocoris amplicollis (Horváth, 1839), Anthocoris confusus Reuter, 1884, Anthocoris nemoralis (Fabricius, 1794), Anthocoris nemorum (Linnaeus, 1761), Orius majusculus Reuter, 1884, Orius minutus (Linnaeus, 1758) and Orius niger Wolff, 1811. The following 14 species of Miridae were identified: Atractotomus mali Meyer-Dür, 1843, Campylomma verbasci (Meyer-Dür, 1843), Deraeocoris flavilinea (A. Costa, 1862), Deraeocoris ruber (Linnaeus, 1758), Deraeocoris lutescens (Schilling, 1836), Heterocordylus genistae (Scopoli, 1763), Hypseloecus visci (Puton, 1888), Malacocoris chlorizans Panzer, 1794, Miris striatus (Linnaeus, 1758), Orthotylus marginalis Reuter, 1884, Psallus assimilis Stichel, 1956, Psallus quercus Kirschbaum, 1856, Psallus flavellus Stichel, 1933 and Pseudoloxops coccinea (Meyer-Dür, 1843). The aim of the research was to provide list of true bugs recorded as predators of psyllids in order to preserve their diversity and significance, especially on cultivated plants.