Toxicity of neem oil to the cassava green mite Mononychellus tanajoa (Bondar) (Acari: Tetranychidae)

Abstract

Neem (Azadirachta indica A. Juss.)-derived pesticides have been used against a wide range of agricultural pests including tetranychid mites. Approaches combining lethal and sublethal toxicity studies of neem pesticides towards tetranychid mites are necessary to a comprehensive evaluation of such products. Here, we evaluated the lethal and sublethal toxicity of the neem oil Bioneem to the cassava green mite Mononychellus tanajoa (Bondar) by integrating lethal concentration (LC) with population growth and biological parameter studies. According to Probit analyses the concentration of neem oil Bioneem which kills 50% of the population (LC50) of M. tanajoa was 3.28 µL cm -2 , which is roughly twice the field concentration recommended of this biopesticide to control pest mites (1.7 µL cm -2 ). The growth rate of the cassava green mite steadily decreased with dosages of neem oil. Furthermore, sublethal concentrations of the neem oil corresponding to the LC50 reduced the periods of the immature stages of M. tanajoa resulting in a shorter developmental time. Similarly, the number of eggs per day and the number of eggs per female per day, a proxy for fecundity, were drastically reduced in M. tanajoa females exposed to the LC50 of neem oil. Based on our comprehensive approach we conclude that the neem oil showed lethal as well as sublethal toxicity on growth rate and biological parameters such as duration of immature stages and fecundity of the cassava green mite M. tanajoa and it could be used as an ecological alternative for the management of this pest.

Pathogenicity of Metarhizium anisopliae and Beauveria bassiana fungi to Tetranychus ludeni (Acari: Tetranychidae)

“…2B). Stressing factors, such as pathogens or toxic substances, may reduce the oviposition of phytophagous mites (SILVA et al, 2013), an effect considered important in IPM, because it reduces future generations of phytophagous. Sublethal effects of pathogenic fungi on target pests should be considered.…”

Bioactivity of essential oil from Lippia gracilis Schauer against two major coconut pest mites and toxicity to a non-target predator

“…In addition to lethal toxicity, sublethal effects on individuals that survive pesticide exposure play a key role in pest control (Desneux et al, 2007). Such effects include reduced longevity and oviposition as well as altered orientation (attraction and repellence) (Silva et al, 2013;Tak and Isman, 2017). In addition to survival, the estimated LC 50 of the essential oil of L. gracilis drastically reduced the number of eggs laid by females.…”

Volatile Metabolomic Composition of Vitex Species: Chemodiversity Insights and Acaricidal Activity

“…Concentration-mortality bioassays ( Silva et al, 2013 ) were conducted to estimate the lethal concentration (LC) of the essential oil extracted from four Vitex species ( V. capitata, V. megapotamica, V. gardneriana , and V. rufescens ) to adult coconut mites ( A. guerreronis ). A preliminary bioassay was performed using a wide concentration range where the no observed adverse effect level (NOAEL) and the concentration able to kill 100% of A. guerreronis were determined.…”