Essential oils cause detrimental effects on biological parameters of Trichogramma galloi immatures

Abstract

Essential oils from botanical extracts used for insect pest control should be both effective and have low impact on natural enemies. The objective was to evaluate the effects of ten essential oils on the biological and reproductive parameters in two Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae) generations. The emergence F 1 generation of T. galloi was reduced by more than 30% with Allium sativum, Carapa guianensis, Citrus sinensis, Neem and Syzygium aromaticum. Zingiber officinale reduced the T. galloi emergence of the F 1 and F 2 generations by between 30 and 99%. The longevity of the F 1 generation was reduced by more than 50% with Z. officinale at the pre-pupae and pupae stages. All oils reduced the parasitism rate of the F 1 generation in the egg-larva and pre-pupa stages. Allium sativum, C. guianensis and C. sinensis, Neem and Origanum vulgare reduced parasitism by between 30 and 79%. Zingiber officinale was slightly and moderately harmful to the F 1 and F 2 generations, respectively, for the T. galloi parasitism. The sex ratio of the two T. galloi generations was not affected by the essential oils. The low side effects of the oils on the F 2 generation, except for Z. officinale (the most harmful oil), suggest that T. galloi developed some post-transgenerational tolerance/resistance mechanisms to these oils and/or their components. The A. sativum, C. guianensis, C. sinensis, Neem, O. vulgare, S. aromaticum and Z. officinale oils were not selective for T. galloi. Mentha piperita, Piper nigrum and Thymus vulgaris essential oils can be included in integrated pest management programs for this parasitoid.

Non-target effects of ten essential oils on the egg parasitoidTrichogramma evanescens

“…It could confirm that pupal stages are more sensitive to exposition to EOs in Trichogramma (Parreira et al, 2018a,b). Indeed, the emergence of parasitized eggs of E. kuehniella was not affected by a five-second immersion in diluted EOs during the egg/larva stage (<1 day after parasitism) while it was reduced by more than 30% when immersion occurred at the pupal stage (7-8 days after parasitsm) for T. pretiosum (Parreira et al, 2018a) and T. galloi (Parreira et al, 2018b). Early instar parasitoids, that have very minute size, might be protected inside the host egg while after growth and host feeding (Volkoff et al, 1995), parasitoid pupae might be more directly exposed to air pollution.…”

“…when immersion occurred at the pupal stage (7-8 days after parasitsm) for T. pretiosum (Parreira et al, 2018a) and T. galloi (Parreira et al, 2018b). Early instar parasitoids, that have very minute size, might be protected inside the host egg while after growth and host feeding (Volkoff et al, 1995), parasitoid pupae might be more directly exposed to air pollution.…”

“…Non-target effects on T. evanescens could thus have both economical and ecological consequences. Regarding EOs, some Trichogramma species are sensitive to both fumigant and contact toxicity: EOs might reduce the longevity and the fecundity of parasitoids, affect their reproductive behavior and have an impact on their progeny (Poorjavad et al, 2014; Parreira et al, 2018a,b).…”

ZnO nanoparticles produced in the culture supernatant of Bacillus thuringiensis ser. israelensis affect the demographic parameters of Musca domestica using the age‐stage, two‐sex life table

“…34 These exposures, besides causing direct mortality, may also affect insect biology, behavior, gene expression and enzymatic activities. 4,[35][36][37] In addition, hormesis effects have been reported in arthropods after exposure to sublethal concentrations of pesticides. 38 Sublethal effects may also affect future population fluctuations if these effects are passed on to the next generation.…”

“…Target and non‐target species usually receive sublethal exposures of insecticides as a result of residual effects following the application of insecticides 34 . These exposures, besides causing direct mortality, may also affect insect biology, behavior, gene expression and enzymatic activities 4, 35–37 . In addition, hormesis effects have been reported in arthropods after exposure to sublethal concentrations of pesticides 38 .…”