МОНІТОРИНГ КОМАХ-ЛИСТОГРИЗІВ ДУБА ЗВИЧАЙНОГО (QUERCUS ROBUR L.) ТА ДУБА ЧЕРВОНОГО (QUERCUS RUBRA L.)

Анотація

MONITORING OF OAK (QUERCUS ROBUR L.) AND RED OAK
(QUERCUS RUBRA L.) LEAF BEATLES
I. M. Kul’bans’ka
Abstract. Our research related to the monitoring of leaf-eating pests of oak

Degradation and mass drying of oak forests have become a global phenomenon and can be found almost in all areas of many oak species in Europe, Central Asia, USA and other countries and regions. Temperature and hydrological regimes change, influence of man's activities, ecological misbalance, distribution of infectious agents etc are most often distinguished among the stressors that cause deterioration and drying up of plantations with oak. It should be noted that each individual phenomenon, as well as their combination, not only lead to phytocoenosis imbalance, but also to the formation of conditions favorable for the harmful insects and diseases development, that significantly increase the process of stands drying out. Therefore one should not underestimate the role of one of the listed components as a root cause and an intensifying factor of oak forests degradation.

Our research related to the monitoring of leaf-eating pests of oak (Quercus robur L. and Quercus rubra L.) in the context of Insecta class species composition determination at different growth and development stages. They are rather relevant because provide an opportunity to forecast the process of plantation weakening, development and improvement of regulation of population dynamics for the purpose of forests sustainability and productivity increasing.

During the entire study period such damage types in both species were identified: skeletization, mining, deformation, holes, browsing (hard and margin), leaf rolling, drying. Gall-like swellings were identified in Q. robur.

It has been established that the average damage amount of assimilation apparatus is more than 50 % of the leaves; the examined plantations were referred to the 2^nd defoliation ratio – medium-damaged.

The damage type «skeletization» is represented insignificantly, in particular on Q. robur leaves – 3.7 %, on Q. rubra leaves – 1.1 %. Mining on Q. robur leaves is 9.6 % of the total leaves number on a model branch. The number of deformed leaves was 0.4 % for Q. robur and 2.6 % for Q. rubra. Foramination on the average is 10.2 % (Q. robur) and 4.7 % (Q. rubra) of the total leaves number on the model branch.

Hard eating-out was found on 1.7% of Q. robur leaves and on 2.8 % of Q. rubra leaves. Marginal eating-out is the most common damage that occurred on the examined leaves; in particular it was noted on 19.5 % of Q. robur leaves and 16.2 % of Q. rubra leaves. Leaf rolling was noted on 1.0 % of leaves (Q. robur) and on 1.9 % (Q. rubra) of the total examined leaves on the model branch. Also during research gall-like swellings were unidentified on Q. robur leaves in small amounts (on average 1.9%) as a result of Cynips quercustolii, Neuroterus numismalis and Andricus foecundatrix activities. Drying out was noted on Q. robur leaves – 32.8 %, on Q. rubra leaves – 24.3 %.

It is also worth noting that during research powdery coating (invader – Microsphaera alphitoides Griffon & Maubl.) was noted on Q. robur leaves, whose harmfulness is shown in assimilative surface reduction and chlorophyll destruction of the affected leaf. According to visual appraisal (E.E. Heshele scale), considering the actual leaf surface occupied by mycelium, damage grade of oak is 5 (area of leaf surface damage is 65 %). No leaf with powdery mildew on Q. rubra was noted.

Thus, a significant Q. robur and Q. rubra defoliation degree in combination with high degree of M. alphitoides distribution lead to leaves weakening and gradual drying, that significantly affects not only its appearance, but also leads to physiological and biochemical processes violation and as a consequence of the forest phytocenosis imbalance.