Research on the Flight Evolution of Melolontha Melolontha L. (Coleoptera, Scarabaeidae) Species in the Central of Moldavia Conditions, Romania

Abstract

The cockhafer (Melolontha melolontha L.) is the most widespread and best known bug. It is a polyphagous bug, being harmful both in adulthood and in larva stage. The researches were conducted at Agricultural Research and Development Station (A.R.D.S.) of Secuieni, Neamţ county, Romania, and followed the evolution of adult flight, during 1993 - 2012 with a light trap help. The gatherings and records were made daily from 1 April to 31 October every year, during the observation period. Dividing the observation period into four stages of five years each, it was found that the largest number of specimens, 38059, was collected in the second stage (1998 - 2002), followed by the third stage (2003 - 2007) with 18167 specimens, first stage with 12173 specimens, and the lowest number of 286 specimens was recorded in the fourth stage (2008 - 2012). The adults flight started in all the years in the second or the third decade of April and lasted until the second or the third decade of May, with the exception of 1995 şi 2009 when he finished in the first decade of June. The average duration of the flight was 39 days. The maximum flight curve was reached, in all years of observation, in the third decade of April and first decade of May. The maximum intensity of flight curves was recorded every three years, as follows: 1994, 1997, 2000, 2003, 2006, 2009, 2012. This shows that, in Secuieni conditions, the insect has one generation at 3 years. Highest intensity of flights has been in the years 2000, when the top flight was conducted by 38059 specimens, 2003 with 13912 specimens/flight and 1997 with 10221 specimens/flight.

Spring phenology of cockchafers, Melolontha spp. (Coleoptera: Scarabaeidae), in forests of south-western Germany: results of a 3-year survey on adult emergence, swarming flights, and oogenesis from 2009 to 2011

“…Light traps have been successfully used in the monitoring of cockchafer swarming flights (Reichholf 1979(Reichholf , 1985(Reichholf , 1993Švestka 2006, 2007Trotuş et al 2013). It became apparent that male cockchafers outnumber the females at the light trap (Reichholf 1979(Reichholf , 1985Švestka 2006, 2007, a phenomenon which was also observed in the present study.…”

“…In the present study, cockchafers were observed leaving the soil in early/mid April when mean temperatures in the upper soil layer reached 10°C, which is in close accordance with Zivanovic (1972) and Niklas (1974). On the contrary, Richter (1962) and Trotuş et al (2013) reported adult emergence at higher (12.8-17.4°C) or even lower (6.1-14.2°C) mean soil temperatures for East Germany and Romania, respectively. Differences might be due to regional adaptations of the cockchafer populations to local conditions (e.g.…”

European Corn Borer (Ostrinia nubilalis Hbn.) Bioecology in Eastern Romania

“…One of the changes was the appearance of the second peak in August. The number of generations in Eastern Romania was stable for 25 years at one generation [ 9 ]; however, in the last few years, a partial second generation registered because of the temperature increases. However, these changes in insect development take place over time, with rising temperatures reported during the last few years and an increase in effective heat units, or degree–days, accumulating per day and annually above the biological thresholds [ 36 ].…”

“…In Romania, the pest is present in all areas where corn is the main crop [ 7 ]. The larvae feed on the epidermis of the leaves and the pollen from the inflorescences, and as it passes through the larval stages, it pierces the stem, the veins of the leaves, and the cobs, consuming the grain within the cob [ 8 , 9 ]. Larval boring causes the plants to break, which makes mechanized harvesting difficult, leading to direct quantitative losses and indirectly to grain deterioration.…”

“…Research carried out in Romania [ 14 ] showed that, depending on the average annual temperature, the European corn borer develops one generation per year in the northern part of the country. A partial second generation occurs in the country’s south [ 8 , 9 ]. Recent research indicates that rising temperatures have created favorable conditions for this species to develop in the country’s south for two complete generations per year [ 15 ].…”