2005, vol. 33, br. 1, str. 35-43
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Brojnost žitnih stenica u jesen 2004. godine i dalje iznad kritične granice
Senn pest abundance in fall 2004 still above the critical threshold
Naučni institut za ratarstvo i povrtarstvo, Novi Sad
Sažetak
Brojnost zimujućeg imaga žitnih stenica u jesen 2004. godine, na mestima prezimljavanja, na stalnim lokalitetima Fruške gore i Deliblatske peščare, iznosila je 41,2 imaga po m2. U odnosu na prethodnu godinu, došlo je do njenog smanjenja, ali je ona i dalje iznad kritične vrednosti. Na alternativnim lokalitetima (okoline Vršca, Subotice i Bačke Topole), brojnost se kretala od 19,4-77,4 imaga po m2. Dominantna vrsta na oba stalna lokaliteta bila je Eurygaster maura (zastupljena sa 62,1%), a slede je E. austriaca(34,6%) i vrste roda Aelia(3,3%). To je prvi put da je u oba lokaliteta dominantna vrsta . Na alternativnim lokalitetima, u okolini Subotice i Bačke Topole, izrazito dominantna je vrsta E. austriaca (95,6-97,6%), dok je u okolini Vršca taj odnos približan lokalitetu Deliblatske peščare. Odnos polova vrste E. austriaca bio je 1:1,2 (ženke:mužjaci), a vrste E. maura 1:0,9. Prirodni mortalitet imaga na mestima prezimljavanja u jesen 2004. godine bio je 0,7%. Od ukupnog mortaliteta, 40% je kod vrste E. austriaca, a 60% kod E. maura. Na osnovu brojnosti imaga na mestima prezimljavanja u jesen 2004. godine, koji je značajno iznad kritične vrednosti (30 imaga po m2), može se očekivati da će žitne stenice biti značajan problem u vegetaciji 2005. godine. Međutim, to zavisi od niza faktora, od kojih su najznačajniji klimatski uslovi u periodu april - juni i aktivnosti jajnih parazita, predatora i gljivičnih oboljenja u to vreme. U cilju određivanja potrebe zaštite od žitnih stenica, neophodno je u proleće, nakon doletanja sa mesta prezimljavanja na useve pšenice, utvrditi njihovu brojnost, pratiti kopulaciju i polaganje jaja, piljenje i razviće larvi i prelazak u imaga nove generacije.
Abstract
The average density of senn pest imagoes overwintering at the two permanently monitored locations, Fruška Gora Mountain and Deliblato Sands, in Fall 2004 was 41.2 imagoes per m2. Although this was a decrease compared to 2003, the recorded densities were still above the critical threshold (30 imagoes per m2). At alternative locations (vicinity of towns Vršac, Subotica and Bačka Topola), Senn pest densities ranged from 19.4 to 77.4 imagoes per m2. Eurygaster maura was a dominant species at both permanently monitored locations (62.1%), followed by E. austriaca(34.6%) and species from the genus Aelia (3.3%). This was the first record of E. maura being dominant at both locations. At the alternative locations in the vicinity of Subotica and Bačka Topola, E. maura was absolutely predominant (95.6-97.6%). In the vicinity of Vršac, species composition was similar to that found at the Deliblato Sands. The sex ratio of females to males was 1:1.2 in the case of E. austriaca, and 1:0.9 for E. maura. The natural mortality at the overwintering sites was 0.7%. Fourty percent of the total mortality was attributable to E. austriaca, and sixty percent to E. maura. Based on the high abundance, and low natural mortality rate of imagoes observed at the overwintering sites in Fall 2004, significant senn pest damage could be expected in the 2005 growing season. However, the actual situation will depend on a number of factors, most important of which are climatic conditions, and the activity of egg parasites, predators and fungi in the period April - June. To assess whether chemical control of senn pest will be required in spring, it is necessary to quantify the abundance on wheat fields after migration from overwintering sites, and to monitor reproduction (copulation, ovipositing), and new generation (hatching success, larval development and transformation into imagoes).
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