CLASSICAL BIOLOGICAL CONTROL OF APHIDS BY USING OF LADYBUGS SPECIES IN SOME ROSE VARIETIES.

Aphids are considered to be the most common and most harmful species of insect attacking the rose. The western area of Romania is favorable for the development of a large number to the generations, regardless of the species of aphids. Reducing the population level of aphids by ladybugs (an inexpensive and environmentally friendly biological method is, in fact, the main objective of this paper). In recent years, the ladybugs populations have increased considerably in the natural environment, which has implicitly led to the reduction of the aphid populations present on the plants. It is known that the main food of the ladybugs is aphids, so the interaction between them has been and remains a permanent subject of research in the field of classical biological combat. Three biotic factors have been implicated in this paper: aphids, ladybugs, and rose. The place of observation was identified in the western area of country (Arad County, Santana village). The observations were made during the years 2016 and 2017 and materialized in weekly readings. The rose varieties studied were Rosa Blue Monday, Queen Elizabeth and Rosa Aida. Rose varieties were selected on the basis of frequency in the area and trade availability. Five plants of each variety were monitored and analyzed. The results showed that on all rose varieties there were both aphids and ladybugs. Aphids were represented by the species Macrosiphum rosae (rose aphid), Myzaphys rosarum (pink aphid of the rose) and the predators (ladybugs) of the invasive species Harmonia axyridis (Asian ladybugs). The Rosa Aida variety was highlighted by a total of 130.75 aphids consumed by predators. Average results were obtained on the Queen Elizabeth variety (21.7 aphid consumed). Low efficiency was recorded in the Rosa Blue Monday variety, where only 8.71 aphids were consumed. The explanation would be that where the aphid's population is large and the population of the predators grows. As a recommendation, exploitation of ladybugs present in crops is encouraged. By naturally controlling biological exploitation of the ladybugs it reduces number of chemical treatments. [ABSTRACT FROM AUTHOR]