Zrinka Drmić

Population dynamics of noctuid moths and damage forecasting in sugar beet

The most damaging Noctuidae pests in sugar beets in Croatia are classified into two groups based on the injuries that their larvae produce: the cutting species (Agrotis ipsilon and Agrotis segetum) and the surface‐feeding species (Mamestra brassicae, Lacanobia oleracea and Autographa gamma). The flight activity of male moths was detected and monitored using traps baited with sex pheromone. The study aimed to determine the population dynamics of noctuid pests in sugar beet crops and to propose damage forecasts and thresholds based on male moths capture in pheromone traps in specific weather conditions. A strong positive correlation between captured male moths in pheromone traps and the level of damage to sugar beet crops was established. The population densities were extremely affected by the weather conditions that prevailed in the sugar beet growing period. If the weather conditions are not optimal, the population of the second generation of moths and larvae will be smaller, and the level of damage to plants will decrease accordingly. Thus, intensive monitoring of noctuid male moth flights and weather conditions in the sugar beet growing season enabled forecasting of future damage to a larger area, although visual inspections are necessary to plan insecticide applications.

Comparative Efficacy of Classical and Biorational Insecticides on Sugar Beet Weevil, Bothynoderes punctiventris Germar (Coleoptera: Curculionidae)

Bažok R., Satvar M., Rados I., Drmic Z., Lemic D., Cacija M., Viric Gaspari c H. (2016): Comparative efficacy of classical and biorational insecticides on sugar beet weevil, Bothynoderes punctiventris Germar (Coleoptera: Curculionidae). Plant Protect. Sci., 52: 134–141. The contact and ingestion activity and the potential of the insecticide spinosad for the control of sugar beet weevil were evaluated and compared with commercially used insecticides lambda-cyhalothrin and chlorpyriphos + cyper methrin. Results of three laboratory trials proved very good efficacy of spinosad applied at the dose of 72 g a.i./ha. Its efficacy was similar to chlorpyriphos + cypermethrin and significantly higher than that of lambda-cyhalothrin. Due to its favourable eco-toxicological properties and good ingestion activity, spinosad is a good candidate to be introduced in the integrated pest management strategy against beet weevil.

Endogaeic ground beetles fauna in oilseed rape field in Croatia

The abundance of ground beetles (Coleoptera, Carabidae) in oilseed rape field can be an important indicator of different agricultural measures in arable land fauna. Surveys about ground beetle fauna in Croatia are generally very scarce and only few research on oilseed rape were conducted. The aim of this study was to determine the endogaeic ground beetle fauna in oilseed rape field and to determine species abundance and frequency. The study was carried out in Podravina region of Croatia, from the end of May till the mid-September in 2015. Ground beetles were collected using endogaeic traps incorporated in the soil. Altogether, 487 individuals classified into 8 species were collected. Species with the highest abundance and frequency was Brachinus (Brachinus) psophia Audinet-Serville, 1821, which was classified as eudominant and constant species. The highest ground beetle abundance was observed in summer period. All of the species found were spring breeders, except for species Trechus (Trechus) quadristriatus (Schrank, 1781) which breeds in autumn.