Iwona Skrzecz, Alicja Sowińska and Wojciech Janiszewski
The aim of the study was to evaluate the possibility of using botanic antifeedants to reduce the damage caused by Melolontha spp. grubs. To achieve the objective, the experiments were established in semi-field conditions to estimate the antifeedant activity of rutin, quercetin (flavonoids from buckwheat Fagopyrum esculentum) and an extract from black alder Alnus glutinosa leaves against Melolontha melolontha grubs. The grubs were placed individually in the pots with a soil in which 2 year old Pinus sylvestris trees were planted. The pots were put in garden pavilions placed in the open area. Then the soil in the pots were watered with the emulsions of rutin, quercetin, an extract from A. glutinosa leaves, and with pure water-comparative variant. After 4 months, the weight and mortality of grubs were compared, as well as the weight of tree roots in all pots.
There was no effect of the antifeedants on the development and extent of damage caused by M. melolontha grubs. The results do not indicate the use of botanic antifeedants in the protection of forests against the cockchafer grubs
Aleksandra Prokocka, Iwona Skrzecz, Alicja Sowińska, Robert Wolski and Wojciech Janiszewski
Scots pine (Pinus sylvestris) plantations and thickets damaged by biotic and abiotic factors are particularly attractive to small-banded pine weevil Pissodes castaneus, whose larvae excavate feeding tunnels in the stems of young trees, causing their death. There are no chemical methods that can be applied to protect forest plantations and thickets against this pest. Therefore, the studies were undertaken aimed at the assessment of the efficacy of alpha-cypermethrin used to reduce the numbers of this pest within restock areas. The scope of work included laboratory and field estimation of insecticidal activity of alpha-cypermethrin.
In laboratory, the beetles of P. castaneus were reared on P. sylvestris twigs treated with five concentrations of alpha-cypermethrin (0.0001–1%) formulated as Fastac Forest 15 SC. Insect mortality was calculated during 7-day rearing and median lethal concentration LC50 was calculated. The field treatments consisted of spraying of four-year old Scots pines with the insecticide in concentrations of 2% and 4%.
In laboratory conditions, the insecticide used at five different concentrations caused a 7–95% mortality of the beetles (LC50 = 0.266%), while field sprays resulted in a 1.5–3.5-fold reduction in the colonization of trees and in higher pest mortality rates.
The results indicate the possibility of using of alpha-cypermethrin in protecting the forest against P. castaneus and can be the basis for the development of chemical method used in the forestry practice.