Sublethal effects of insecticides on the intrinsic rate of increase of cotton aphid

Abstract

Insecticides are often implicated in causing outbreaks of the cotton aphid, Aphis gossypii (Glover) (Homoptera: Aphididae), through stimulation of reproduction. In this study we report the sublethal effects of dosages of bifenthrin, acephate, carbofuran or pyriproxifen on cotton aphid reproduction. We could not detect any increase or decrease in the intrinsic rate of increase of cotton aphids exposed to bifenthrin, acephate or carbofuran. However, we did detect some increases in the net reproductive rate of aphids treated with bifenthrin justifying further investigation of the effect on reproduction by this insecticide. Trends based on simple linear regression models suggest that sublethal dosages of bifenthrin or carbofuran have a negative impact on aphid population growth as dosages increase. These data suggest that stimulation of reproduction by these insecticides probably does not play a major role in cotton aphid outbreaks or resurgence. Pyriproxyfen is a juvenoid currently used for control of whiteflies in cotton. It demonstrated significant activity towards cotton aphid reared on treated cotton in our bioassays. Pyriproxyfen caused sterility in most aphids exposed to dosages exceeding 1 ppm, and reduced aphid longevity by approximately 50%. However, it did not appear to greatly influence the reproductive potential or longevity of reproductively mature aphids. A field study indicates that pyriproxyfen affects cotton aphid population structure and may have potential in managing cotton aphid outbreaks. Modifying aphid population structure and growth through the use of juvenoids such as pyriproxifen may prove to be an effective proactive approach to pest control without adversely impacting beneficial organisms or causing pest resurgence.

Sublethal effects of nitenpyram on life-table parameters and wing formation of Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

“…The phenomenon of reproductive stimulation of pests by sublethal doses of insecticides has been observed in several pests treated with different insecticides. For example, increased fecundity had been observed in two-spotted spider mites and cotton aphids following triazophos and bifenthrin treatments, respectively (Dittrich et al, 1974;Kerns and Stewart, 2000). It was also reported that 572 J. ZHANG et al a sublethal dose of imidacloprid could reduce the fecundity of the cotton aphid and two green leafhopper species (Widiarta et al, 2001;Conway et al, 2003).…”

Terpenes: Natural Products for Controlling Insects of Importance to Human Health—A Structure-Activity Relationship Study

“…The use of natural compounds at sublethal concentrations can control insect pest populations by affecting growth and reproduction [117]. Terpenes can cause deformation of adult insect emergence or the lack of eggs, similar to growth-regulating hormones [118] such as juvenile hormone.…”

Assessment of physiological sublethal effects of imidacloprid on the mirid bug Apolygus lucorum (Meyer-Dür)

“…Sublethal effects of insecticides could affect population dynamics (Stark and Banks 2003) through impairment to behavioral and physiological traits (Kerns and Stewart 2000;Desneux et al 2006a;Arnó and Gabarra 2011;Cabral et al 2011;Shahout et al 2011;Stara et al 2011;Han et al 2012). Studies have demonstrated that exposure to lethal or sublethal doses/concentrations of pesticides could reduce insect longevity and fecundity (Desneux et al 2006b;Zeng et al 2006;Wang et al 2008;Bao et al 2009;Biondi et al 2012;Zappalà et al 2012) and disturb key behavioral traits (Desneux et al 2004a, b;Ramirez-Romero et al 2008;Cordeiro et al 2010).…”