Row data for antifeeding and antimicrobial activity of Calocedrus decurrens and Cupressus arozonica essential oils against spongy moth larvae and Phytophthora root pathogens.

Subject: We performed choice and no-choice assays to estimate deterrence coefficients in 2nd instar spongy moth larvae. By using standard formula for nutritional indices we also determined relative consumption rate and relative growth rate of larvae. Antimicrobial activity was estimated based on percent of inhibition of mycelial growth of three Phytophthora species: P. ×cambivora, P. plurivora and P. quercina. 

Material and methods: For determination of relative and absolute deterrent coefficient (choice and no-choice assays, respectively) we treated leaf discs (d=30mm) of Quercus cerris with 50 % ethanol (control group) or ethanolic solutions of essential oils (EO) of Calocedrus decurrens and Cupressus arozonica at three concentrations (0.05%, 0.1% and 0.5%). Treatments were performed by imerson of discs in solutions for 3s. Feeding arena in choice assay consisted of one control and one EO-treated disc on opposite sides of Petri dish (d=9cm). Arena for no-choice assay had one leaf disc in the center of Petri dish. For each assay and each EO type and concentration 25 replicates were formed with one 2nd instar spongy moth larvae. After 48 h, leaf remains were scanned and eaten surface area was calculated as difference between leaf surface area before feeding and after 48 h of feeding. Also, larvae were weighed at the beginning of feeding trial in no-choice assay and after 48 h. Relative consumption rate and relative growth rate were calculated. For determination of antimicrobial activity Phytophthora species were developed on V8 agar media. For treatments, EOs of Calocedrus decurrens and Cupressus arozonica were dissolved in 0.5% Tween 80, added to V8 agar media at concentrations 0.1%, 0.5% and 1% and poured into Petri dishes (d=60mm). Control group contained 0.5% Tween 80. Agar plugs (d=6mm) were taken from edges of actively growing colonies and transferred to the center of Petri dishes. Control group had 12 replicates and each treatment groups had 8 replicates. Petri dishes were kept at 20°C in dark for 24 h and then mycelial growth was monitored daily for five days. Percentage of inhibition of mycelial growth by essential oils was calculated relative to the control group.

Analysis: To evaluate antifeeding and antimicrobial effects we analyzed data by ANOVA (ADC, RCR, RGR) and PERMANOVA (RDC, Ir).

Statistics: Raw data are presented, not subjected to the statistical analyses.

Data presentation: Presented data are raw data for relative deterrence coefficient, absolute deterrent coefficient, relative consumption rate, relative growth rate and inhibition rate of mycelial growth. Data are presented in five *.csv files.

Highlight: Essential oils may negatively affect pest insect growth and consumption and inhibit mycelial growth of pathogens. We showed that C. decurrens EO had strong antifeeding activity against spongy moth larvae whereas C. arizonica EO stimulated feeding. C. arizonica EO did not affect relative consumption and growth while C. decurrens EO reduced consumption and increased larval growth at low concentration. The highest EO concentration provoked total inhibition of mycelial growth in all three Phytophthora species. At the lowest concentration P. quercina was the most sensitive species and C. arizonica EO had higher antimicrobial activity than C. decurrens EO. 

Abbreviations:
RDC – relative deterrence coefficient
ADC – absolute deterrence coefficient
RCR – relative consumption rate
RGR – relative growth rate
Ir – Inhibition rate of mycelial growth