Toxicity of Insecticides Targeting Rice Planthoppers to Adult and Immature Stages of Trichogramma chilonis (Hymenoptera: Trichogrammatidae)

Abstract

Planthopper-targeting insecticides, pymetrozine, thiamethoxam, buprofezin, and nitenpyram, were tested under laboratory conditions for toxicity to adults and immatures of Trichogramma chilonis Ishii, using standard tests described by International Organization for Biological Control (IOBC). In the dry film residue test, all insecticides resulted in >90% mortality in T. chilonis adults and were ranked as moderately harmful. Persistent toxicity tests revealed that nitenpyram was short-lived and the other three insecticides were of slightly persistent toxicity to the wasp adults. Effects of the insecticides on egg, larval, and prepupal stages of T. chilonis were investigated with striped stem borer as host. At the three stages of T. chilonis (within the host egg), all the insecticides reduced parasitism rate, but nitenpyram and pymetrozine applied at egg stage, buprofezin and nitenpyram at larval stage, and buprofezin and thiamethoxam at prepupal stage of T. chilonis reduced parasitism by <30% in comparison with the control, and were thus ranked as harmless. Although insecticide treatment of the three immature stages of T. chilonis all reduced wasp emergence from host eggs, only thiamethoxam applied at larval stage and buprofezin at prepupal stage resulted in >30% reduction in emergence rate as compared with the control and were categorized as harmful. Immature duration of T. chilonis was only significantly extended by nitenpyram applied to egg stage than the control. Sex ratio of emerged wasps was not affected by the treatment to immature stages. The data are of significance for IPM programs incorporating inundative release of T. chilonis for control of lepidopteran rice pests where there is heavy co-occurrence of planthoppers.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

“…In the case of Trichogramma chilonis exposed to residues of commercial formulations of thiamethoxam and nitenpyram, mortalities of 98 and 96%, respectively, were observed in 24 h. This together with a reduction of parasitism in the larval stage: 20-37% for thiamethoxam and 14-45% for nitenpyram, and a reduced emergence of 12-33% for thiamethoxam and 21-29% for nitenpyram (Ko et al 2015). Also, exposures by contact following the recommended paper disc tests of the International Organization for Biological Control (IOBC) showed the high acute toxicity of thiamethoxam, imidacloprid and acetamiprid when applied at 25, 30-40, and 60 ppm concentrations.…”

Proceedings of the 5th International Symposium on Biological Control of Arthropods, Langkawi, Malaysia, September 11-15, 2017

“…Although insecticide treatment of the three wasp immature stages all reduced wasp emergence, only thiamethoxam applied at larval stage and buprofezin at prepupal stage were categorized as harmful. The data are of significance for IPM programs incorporating inundative release of Trichogramma for control of lepidopteran rice pests where there is heavy co-occurrence of planthoppers (Ko et al, 2015).…”

Pengaruh Residu Insektisida Deltametrin Pada Tanaman Padi terhadap Tingkat Parasitasi Parasitoid Anagrus Nilaparvatae (Hymenoptera: Mymaridae)

“…Insektisida imidakloprid pada 7 hari setelah aplikasi dapat menyebabkan mortalitas A. nilaparvatae sampai 80,7% (Wang et al 2008). Aplikasi Insektisida (pymetrozine, thiamethoxam, buprofezin, dan nitenpyram) dalam mengendalikan hama wereng pada tanaman padi berdampak negatif terhadap musuh alami, karena mengurangi tingkat parasitasi parasitoid Trichogramma chilonis (Ko et al 2015). Dampak negatif insektisida terhadap parasitoid dapat terjadi melalui inangnya, kontak langsung, menghisap nektar atau pollen bunga yang sudah terkontaminasi (Fernandes et al 2010).…”