Low efficacy of a Bacillus thuringiensis (Berl.) formulation in Controlling the diamondback moth, Plutella xylostella (L.), in the Philippines

Abstract

Neem (Azadirachta indica) seed kernel extracts were evaluated in cabbage fields in the Philippines for their ability to control the diamondback moth, Plutella xylostella (L.). The extracts were compared to synthetic insecticides and a Bacillus thuringiensis (Berl.) formulation (thuricide hp). The B.t. treatments (1 kg prod./ha) showed low efficacy in controlling P. xylostella. The assumption that this was due to higher UV‐radiation in the trial area could not be confirmed in a corresponding field experiment. Possible development of B.t. resistance in P. xylostella populations is discussed. Zusammenfassung über die geringe Wirksamkeit einer Bacillus thuringiensis (Berl.) Formulierung bei der Bekämpfung von Plutella xylostella auf den Philippinen Extrakte aus Niemsamen (Azadirachta indica) wurden In Kohlfeldern auf den Philippinen im Hinblick auf ihre Eignung zur Bekämpfung der Kohlmotte Plutella xylostella (L.) untersucht. Die Extrakte wurden mit synthetischen Insektiziden und einer Bacillus thuringiensis (Berl.)‐ Formulierung (thuricide hp) verglichen. Die B.t.‐Behandlungen zeigten einen geringen Bekämpfungseffekt bei P. xylostella. Die Annahme, daß dies auf stärkere UV‐Einstrahlung im Versuchsgebiet zurückzuführen sein könnte, ließ sich in einem entsprechend angelegten Feldversuch nicht bestätigen. Die mögliche Resistenzentwicklung gegen B.t. bei P. xylostella wird diskutiert.

Protease interactions with Bacillus thuringiensis insecticidal toxins

“…Insects have been selected for resistance to Bt toxins in the laboratory(reviewed in McGaughey and Oppert, 1999). Field resistance has also been reported in P. xylostella collected in fields where Bt sprays were used (Kirsch and Schmutterer, 1988;Tabashnik et al, 1990;Hama et al, 1992;Shelton et al, 1993;Perez and Shelton, 1997). Assessment of the frequency of resistance alleles in field populations of H. virescens indicated that resistance in nontarget species could develop in 3 to 4 years (Gould et al, 1997).…”

Transgenic broccoli expressing aBacillus thuringiensis insecticidal crystal protein: Implications for pest resistance management strategies

“…Genes encoding some of the Bt ICPs have recently been cloned and transferred to crop plants to reduce the need for spraying and to increase the activity and persistence ofBt ICPs [5,12,22,28,37,45]. Unfortunately, some insect species have developed resistance to Bt ICPs in laboratory selection experiments [25,36,38,45], and one insect, the diamondback moth (DBM), Plutella xylostella, has evolved resistance to Bt sprays in the field [ 15,21,31,33,38,40]. There is now concern that resistance may appear more rapidly when transgenic plants expressing Bt ICPs are deployed [8,15,26,41].…”

Cydia pomonella granulovirus Genotypes Overcome Virus Resistance in the Codling Moth and Improve Virus Efficiency by Selection against Resistant Hosts

“…In 1965, the development of resistance to Bacillus thuringiensis Berliner toxins in a laboratory colony of house flies was reported (18). In the early 1990s, the first reports of field populations of the diamondback moth resistant to B. thuringiensis were published (12,20,33). In contrast, the development of resistance to insect baculoviruses has been observed in the laboratory in several species of insects (2,4,11,16,19) but had not been detected in the field until recently.…”