Lethal and sublethal effects of cypermethrin and methoxyfenozide on the larvae ofRachiplusia nu(Guenee) (Lepidoptera: Noctuidae)

Abstract

Rachiplusia nu is a defoliator lepidopteran species considered a potential pest in soybean and other crops. Cypermethrin is the main insecticide used in Argentina. Worldwide trends in pest control promote the use of insecticides with high specificity like methoxyfenozide; however, their usage in South America is still incipient. The effectiveness of cypermethrin and methoxyfenozide was studied on fifth larval instar of R. nu under chronic exposure in laboratory conditions. Four dilutions (between 10% and 80%) of the maximum field recommended concentration for each insecticide were assessed. Methoxyfenozide caused 100% larval mortality in all tested concentrations, while at tested cypermethrin concentrations, larval mortalities were between 75% and 98%. Cypermethrin treatments showed higher mean survival time values than methoxyfenozide. Both insecticides inhibited larval growth according to weight loss assessment. Cypermethrin also inhibited diet consumption during the first 24-h exposure.

Endophytic Effects of Beauveria bassiana on Corn (Zea mays) and Its Herbivore, Rachiplusia nu (Lepidoptera: Noctuidae)

“…Among the main corn pests are the lepidopteran defoliators. Rachiplusia nu (Guennée) is widely distributed in South America and is one of the primary lepidopteran pests of corn in this region [3]. Although chemical insecticides are effective against most pests, their indiscriminate use has generated a series of ecological problems, such as the development of resistance, environmental contamination, and negative impacts on human health [4,5].…”

Effects of Insect Growth Regulators on Mortality, Survival, and Feeding of Euprosterna elaeasa (Lepidoptera: Limacodidae) Larvae

“…However, while it is difficult to accurately determine the quantity of insecticide penetrating (by contact or ingestion) each insect, mortality caused by IGRs on E. elaeasa was similar to that found with topical application in the concentration-mortality bioassay. The lethality of IGRs and their effectiveness has also been observed with other defoliating pests under field conditions, justifying them as potent bio-rational agents against defoliating pests that can be incorporated in several agricultural systems [24][25][26][40][41][42][43]. The findings demonstrate that these IGRs have a specific mode of action as insecticides affecting a high number of E. elaeasa larvae.…”

“…Especially, our findings show that methoxyfenozide and tebufenozide cause further cessation in feeding of E. elaeasa larvae in comparison with fenoxycarb and pyriproxyfen. Feeding inhibition after exposure to methoxyfenozide and tebufenozide has been also reported in lepidopteran pests, including Rachiplusia nu Gueene (Noctuidae) [40] and Orgyia pseudotsugata (McDunnough) (Erebidae) [41]. In contrast, moderate feeding inhibition after exposure to fenoxycarb and pyriproxyfen has been reported in Abraxas suspecta Warren (Geometridae) [42] and Spodoptera litoralis Boisduval (Noctuidae) [43], respectively.…”

Identification and quantitative analysis of lipids and other organic compounds contained in eggs of Colorado potato beetle (Leptinotarsa decemlineata)

“…Chemical and biological agents-insecticides-are most commonly used to fight this pest. They are used, for example, in the form of spraying and also soaking of potatoes seedlings in insecticide solutions against insect pests (Weber et al 2006;Krawczyk et al 2015;Rimoldi et al 2011;Rojht et al 2012). Different organic compounds may be present in the eggs, e.g., carboxylic acids, alcohols, alkanes.…”