Data regarding the monitoring of the species Diabrotica virgifera virgifera le conte species in agricultural crops from the central area of Moldova

Abstract

In addition to the 25 species of harmful insects, of economic importance for the maize crops identified in Romania, of which, the corn leaf weevil (Tanymecus dilaticollis) and wireworms (Agriotes spp.) are very dangerous soil pests, it is added species Diabrotica virgifera virgifera Le Conte. The species was identified in Europe in 1992, and in 1996 it spread to Romania. The spreding area of the pest was initially restricted in the south-west and west, in the counties of Arad, Timiș, Caraș-Severin, Mehedinți, Dolj, Hunedoara, then gradually spread to all areas of maize cultivation. In the eastern part of the country, respectively in thearea of influence of the A.R.D.S. Secuieni (Neamț, Bacău and North Vrancea counties area) the insect was reported in 2015, the flight intensity, abundance and frequency of attack increased from year to year, which imposed as a necessity the monitoring of the species and the way of attack. The species Diabrotica virgifera virgifera Le Conte causes damage to maize crops both in the larval stage and in the adult stage. Oligophagous larvae feed on the roots of several species of grasses, except sorghum, which they gnaw, cut off, the strongly attacked plants have the slanted stem in the form of a swan's neck, the plants dry prematurely, production losses being 10 - 13%, sometimes higher, up to 55%. Adults are polyphagous, but especially feed on the leaves, silk and corn pollen, but also on the grains at the top of the cobs. The attack reported on the corn leaves is similar to that of the species Lema menalopa. Observations and determinations on the appearance and flight of adults were made using yellow glue traps, which have been installed in maize crops since the beginnig of June. The first adults were registered in the first decade of July, the flight continued without interruption until the end of September. During this period July - September, the adults made a single flight curve, the maximum flight peak was recorded in the second decade of August and totaled an average of 470 specimens / trap / decade. Knowing the abundance of Diabrotica virgifera virgifera Le Conte in agricultural crops in Central Moldova, it is necessary to continue the research on knowledge of bioecology, factors influencing the emergence, evolution and attack, measures to prevent and control the pest.