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With the significant loss of biodiversity in the 20th and 21st century, pollution of air, soil, and water, alternatives to chemical pesticides are needed to preserve nature. One of the alternatives is the usage of plant components as pest insect control. They are an appropriate alternative to chemical pesticides as they are cost-effective, easy, and safe to use, do not affect the environment or beneficial insects negatively, and are still an effective measure against pest insects. The biggest challenge with plant components is that they are biologically unstable. That is why further insight into the effectiveness of different extracts and oils against different pest insects is needed. We tested the antifeedant activity of plant products derived from neem (Azadirachta indica A.Juss.), and linalool on the Spongy moth (Lymantria dispar L, 1758) larvae. To test the efficiency of these compounds, we conducted choice tests in laboratory conditions. Two disks (treatment and control) cut from red oak (Quercus rubra L.) leaves were presented to the second instar spongy moth larvae in Petri dishes for the testing. Twenty-five Petri dishes were used for each of the tested compounds at four concentrations (200 in total). The tested compounds showed the most significant effect at higher concentrations.

Gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae) feeds on a large number of tree species, while ash, Fraxinus spp. (Lamiales: Oleaceae) species are considered resistant and are only sporadically eaten. To assess the conditions under which late instar gypsy moth larvae (GML) can temporarily use non-host common ash ( CA) (F. excelsior L.), and to evaluate their ability to recover from ingestion of this toxic food, we determined the relative growth rate, the relative consumption rate and the amount of produced feces in different laboratory feeding trials. Our report is the first to show that under specific circumstances, the resources acquired after short-term consumption of CA leaves can be utilized for larval growth. We varied the intensity of density and starvation stress prior to feeding on CA leaves. We observed that after moderate stress a group of GML was temporarily capable of coping with CA leaves. Although observed growth and consumption were much lower on CA than on the optimal host oak, Quercus cerris L. (Fagales: Fagaceae), CA-oak-switched larvae showed the ability to recover from short-term use of a toxic non-host foliage. This suggests that feeding on CA might enable GML to survive under conditions of food shortage.