The Larvicidal and Adulticidal Effects of Selected Plant Essential Oil Constituents on Greater Wax Moths

Abstract

Some plant essential oil constituents, such as monoterpenoids and phenylpropanoids, are promising insecticides in some situations and for certain insect pests. They vary in their toxicity, depending on the target insect. Moths (Lepidoptera) appear susceptible to these compounds, making them of promise for use against greater wax moths (Galleria mellonella Fabricius, (Lepidoptera: Pyrallidae), GWM), an important pest of western honey bee (Apis mellifera Linnaeus. (Hymenoptera: Apidae)) colonies. We determined the LC50 for GWM larvae or LD50 for GWM adults of select compounds (thymol, carvacrol, (S)-(+)-carvone, estragole, citral, linalool, (S)-(−)-limonene, and γ-terpinene). Concentrations between 8 and 2,266 µg/cm3 were mixed into the diets of GWM larvae and doses ranging between 0.08 and 70.3 mg per adult were applied topically to the abdomens of GWM adults. Lethal concentrations and doses were calculated after of 72 h of exposure. All eight compounds showed insecticidal activity against all tested stages of GWMs. Thymol (LC50 µg/cm3 (95% CI) = 21 [9–56], carvacrol = 46 [26–79], citral = 63 [30–134], and carvone = 76 [33–201]) had the highest toxicity toward GWM larvae. The hydrocarbons limonene (296 [231–377]), estragole (466 [354–611]), and γ-terpinene (729 [630–857]) had the lowest toxicity toward GWM larvae. Thymol had the highest toxicity towards GWM adults (LD50 (CI) = 0.5 [0.4–0.8] mg/adult). However, carvacrol (11.6 [10.1–13.6]), linalool (12.9 [9.3–17.8]), and limonene (15.8 [13.1–19.2]) were less toxic to GWM larvae. Our data show that select plant essential oil constituents are promising controls of GWM.

Potential of Essential Oils from Anise, Dill and Fennel Seeds for the Gypsy Moth Control

“…We showed that EOs of anise and fennel were rich in phenylpropanoid trans-anethol and dill EO was rich in oxygenated monoterpene carvone and monoterpene hydrocarbons α-phellandrene and limonene. High toxicity and antifeeding activity in insect pests are induced by major compounds of anise, dill and fennel EOs: trans-anethol [ 93 , 94 , 95 ] and carvone [ 53 , 96 , 97 , 98 ]. It has been suggested that oxygenated compounds provide higher insecticidal activity than monoterpene hydrocarbons [ 99 ].…”

A Systematic Review on Viruses in Mass-Reared Edible Insect Species

“…G. mellonella has been available as pet food and bait for many years in several European countries and in the USA [42]. This moth can be easily reared, standardized protocols already exist for its breeding and diets [245][246][247][248][249], and it has high nutritional value [19]. G. mellonella is a reliable model organism to assay pathogenicity of human, animal and insect pathogens (i.e., bacteria, fungi and viruses) as well as to test the effectiveness and toxicity of antimicrobial compounds [250][251][252][253].…”