Toxic effects of hexaflumuron on the development of Coccinella septempunctata

Abstract

Studying the toxic risk of pesticide exposure to ladybird beetles is important from an agronomical and ecological perspective since larval and adult ladybirds are dominant predators of herbivorous pest insects (e.g., aphids) in various crops in China. This article mainly deals with the long-term effects of a single application of the insect growth regulator hexaflumuron on Coccinella septempunctata. A 72-h and a 33-day toxicity test with hexaflumuron (single application) were performed, starting with the second instar larvae of C. septempunctata. Exposure doses in the long-term experiment were based on the estimated 72-h acute LR50 (application rate causing 50 % mortality) value of 304 g active ingredient (a.i.) ha−1 for second instar larvae of C. septempunctata. The long-term test used five hexaflumuron doses as treatment levels (1/50, 1/100, 1/200, 1/400, and 1/800 of the 72-h acute LR50), as well as a solvent control and blank control treatment. The measurement endpoints used to calculate no observed effect application rates (NOERs) included development time, hatching, pupation, adult emergence, survival, and number of eggs produced. Analyzing the experimental data with one-way analysis of variance showed that the single hexaflumuron application had significant effects on C. septempunctata endpoints in the 33-day test, including effects on development duration (NOER 1.52 g a.i. ha−1), hatching (NOER 3.04 g a.i. ha−1), pupation (NOER 3.04 g a.i. ha−1), and survival (NOER 1.52 g a.i. ha−1). These NOERs are lower than the reported maximum field application rate of hexaflumuron (135 g a.i. ha−1) in cotton cultivation, suggesting potential risks to beneficial arthropods.

Impact of imidacloprid on life-cycle development of Coccinella septempunctata in laboratory microcosms

“…The microcosm toxicity test was conducted following the methods described in a previous paper (Yu et al, 2014). The laboratory microcosms consisted of enclosures, each containing a pot filled with soil (11 cm in diameter) in which ten broad bean plants (length 10 cm) were planted.…”

“…ha À 1 , and blank controls were employed. The application rates were based on a preliminary 72 h toxicity test with 2nd instar larvae of C. septempunctata and assuming that sublethal effects in a full life-cycle test may be at least a factor of 100 lower as could be observed in a previous test with the insecticide hexaflumuron using the same test system and test species (Yu et al, 2014). Three replicates were used for each treatment (including controls), and ten 2nd instar larvae were introduced to each replicate test system.…”

“…A number of eggs were then collected from each cage (representing a specific microcosm test system) and placed in another climate room at the same condition. The percentage of eggs hatching was estimated by recording the number of larvae in each replicate (Yu et al, 2014).…”

“…In addition, it is an established technique to raise C. septempunctata in the laboratory, making this species an ideal test organism to study the potential impacts of pesticides on beneficial arthropods as part of the registration procedure for pesticides (e.g. Yu et al, 2014).…”

Vitality and Stability of Insecticide Resistance in AdultPropylaea japonica(Coleoptera: Coccinellidae)

“…The toxicity and selectivity of insecticides toward pest insects and their natural enemies (predators and parasitoids) are critical to integrated pest management (IPM). The susceptibility to insecticides, including organophosphates (OPs), pyrethroids, cabamates, and other different classes of commercial insecticides, was reported in predacious ladybirds (Coleoptera: Coccinellidae), for instance in Adalia bipunctata L. ( Olszak 1999 , Jalali et al 2009 , Jansen et al 2010 , Garzón et al 2015 ), Episyrphus balteatus (De Geer), Coccinella septempunctata L., Propylea quatuordecimpunctata L., and Chrysoperla carnea (Stephen) ( Yu et al 2014 , Jansen 2015 ); Micraspis discolor (Fabricius) ( Hasan et al 2001 ), Coleomegilla maculata De Geer ( Duan et al 2002 ), Stethorus punctum picipes (Casey), and Harmonia axyridis (Pallas) ( James 2003 , Youn et al 2003 , Galvan et al 2006 ); Adonia variegata Goeze ( Aldoghairi et al 2004 ); and Serangium japonicum ( Li et al 2015 ). The studies on selective toxicity of insecticides toward aphids (or other pest insects) and ladybirds were also studied ( Sechser et al 2002 , Xue and Li 2004 , Lucas et al 2004 , Cole et al 2010 ).…”