Comparative efficacy of Beauveria bassiana, Bacillus thuringiensis, and aldicarb for control of Colorado potato beetle in an irrigated desert agroecosystem and their effects on biodiversity

Abstract

Five weekly applications of Beauveria bassiana (Balsamo) Vuillemin, a genetically engineered isolate of Bacillus thuringiensis Berliner (Raven®), and aldicarb (Temik®) were compared for control of Colorado potato beetle, Leptinotarsa decemlineata (Say) in an irrigated desert cropping system. B. thuringiensis was applied using low and high label rates (1.17 and 7.0 l ha−1). B. bassiana was applied at 5×1013 spores ha−1. Aldicarb (Rhône‐Poulenc), applied at 3.37 kg a.i. ha−1 provided the greatest beetle control and potato yields (45 metric tons ha−1), but overall lowest biodiversity in nontarget organisms, particularly predatory Heteroptera. Low and high rates of B. thuringiensis produced fair to excellent beetle control, yielded 33 and 40 metric tons ha−1 and enabled good survival in predatory Heteroptera and other nontargets. Plots treated with B. bassiana resulted in poor control of beetles prior to row closure after which fair to good control was achieved. Yield in the Beauveria‐treated plots was 33 metric tons ha−1 and effect on biodiversity was comparable to the Bt‐treated plots. The lowest number of overwintering adult L. decemlineata was found in the plots treated with bacteria and fungi (0.68–0.84 adults/0.03 m−3 of soil) and the highest was found in control and aldicarb plots (3.44 and 1.84 adults/0.03 m3 of soil). Aphids and leafhoppers showed higher densities in plots treated with microbial control agents, but were eliminated from plots treated with aldicarb.

Control of Earias vittella (Lepidoptera: Noctuidae) by Beauveria bassiana along with Bacillus thuringiensis

“…The ecdysis or molting enables the insects to escape from the infectious cycle of a fungus and more fungal spores rupture and penetrate the cuticle of the host during the prolonged intra-period of molting (Vey and Fargues, 1977). Similarly in our bioassays, the mortality rate was higher with the higher dose rates of B. bassiana and B. thuringiensis against 2 nd and 4 th instar larvae of E. vittella and these findings agree with Lacey et al (1999). The researchers reported reduced populations of L. decemlineata when B. bassiana and B. thuringiensis were applied simultaneously in small plots.…”

Delayed efficacy of Beauveria bassiana foliar spray applications against Colorado potato beetle: Impacts of number and timing of applications on larval and next-generation adult populations

“…Results from foliar spray applications have been positive in some small-scale field tests (Fargues et al, 1980;Campbell et al, 1985;Anderson et al, 1988;Poprawski et al, 1997;Lacey et al, 1999), but in other tests, including pilotscale efforts, efficacy has been marginal to poor (Anderson et al, 1988;Jaques and Laing, 1988;Hajek et al, 1987), We conducted small-scale field tests of B. bassiana strain GHA formulated as BotaniGard in the late 1990s and ultimately reached conclusions similar to those of Hajek et al (1987) that multiple, frequent applications of Bb, even via efficient manually-targeted sprayers, could not be relied upon to control larval populations of this difficult pest (Wraight and Ramos, 2002).…”

Biological efficacy of some biorational and conventional insecticides in the control of different stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

“…Biological control would be the concerted use as a major component of integrated pest management for the control of CPB. Natural enemies of CPB include a variety of predatory insects, parasitoids and microbial control agents (Lacey et al 1999).…”

“…Several biopesticide products based on the bacterium Bacillus thuringiensis (Bt) and on the fungal agent Beauveria bassiana have received considerable attention as a potential biological control agent over the last three decades against CPB (Lacey et al 1999). Nevertheless, Bt-based bioinsecticides are generally efficient if applications are timed to coincide with peak egg hatch or when early larval instars of CPB predominate.…”