Lethal and Sublethal Effects of Single and Double Applications of &lt;I&gt;Bacillus thuringiensis&lt;/I&gt; Variety &lt;I&gt;kurstaki&lt;/I&gt; on Spruce Budworm (Lepidoptera: Tortricidae) Larvae

Moreau, Gaétan; Bauce, Éric

doi:10.1603/0022-0493-96.2.280

Cited by 12 publications

(2 citation statements)

References 23 publications

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“…Pesticide applications are not expected to have a direct impact on apparent fecundity, except perhaps because of their effects on the reproductive abilities of survivors to sub-lethal doses, as documented for both Btk [42] and tebufenozide [43]. In moths that migrate following mating, successful population control by mating disruption is difficult [27].…”

Section: Discussionmentioning

confidence: 99%

The Impact of Moth Migration on Apparent Fecundity Overwhelms Mating Disruption as a Method to Manage Spruce Budworm Populations

Régnière

Delisle

Dupont³

et al. 2019

Forests

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Aerial applications of a registered formulation of synthetic spruce budworm female sex pheromone were made in 2008, 2013 and 2014 to disrupt mating in populations of this forest insect pest in Quebec, Canada. Each year, the applications resulted in a 90% reduction in captures of male spruce budworm moths in pheromone-baited traps. A commensurate reduction in mating success among virgin females held in individual cages at mid-crown of host trees was also obtained. However, there was no reduction in the populations of eggs or overwintering larvae in the following generation (late summer and fall). The failure of this approach as a viable tactic for spruce budworm population reduction could have resulted from considerable immigration of mated females, as evidenced by high rates of immigration and emigration that caused steep negative relationships between apparent fecundity and the density of locally emerged adults.

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Section: Discussionmentioning

confidence: 99%

The Impact of Moth Migration on Apparent Fecundity Overwhelms Mating Disruption as a Method to Manage Spruce Budworm Populations

Régnière

Delisle

Dupont³

et al. 2019

Forests

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“…It therefore seems that larvae can recover from the effects of the Bt toxin, following transient exposure. Other lepidopteran larvae that ingest sublethal doses of Bt also resume normal development after a few days [25].…”

Section: Hybrid Vigor In Reducing Survivors Of Spodoptera Littoralis mentioning

confidence: 99%

Mortality Responses of Spodoptera litura Following Feeding on BT- Sprayed Plants

Al-Otaibi¹

2013

J. Basic Appl. Sci.

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Bacillus thuringiensis delta-endotoxins are safe biological insecticidal proteins whose usefulness has long been recognized. The first commercialized Bt insecticidal formulations were composed of spore-crystal preparations derived from wild-type strains. These products generally have a limited insecticidal host range and several genetically modified strains have, therefore, been constructed in this study using conjugation procedure. However, addition of a new plasmids to Bt strains already harboring other genes often resulted in broader-spectrum. Bacillus thuringiensis serovar Kurstaki, Bacillus subtilis and four of their transconjugants were used in this study as a biocontral agents against lepidopterous cotton pest. Bacterial transconjugants were evaluated for their hybrid vigor in relation to the mid parents and better parent. This evaluation was related to survival and mortality percentages induced in Spodoptera littoralis larvae. Two groups of bioinsecticides; crystals, crystals + endospores were used to be evaluated in this study. The results appeared that bioinsecticides containing crystals + endospores was more effective than crystals for increasing mortality percentage and reducing survival percentage. This effective was including reduction in the mean number of Spodoptera littoralis larvae feeding on leaves sprayed with crystals + endospores. Increasing mortality percentage of crystals + endospores was due to higher toxicological effects than that of crystals. This recommended bioinsecticide biologists to use crystals + endospores in all bioinsecticides formulations. Higher positive efficiency was appeared at 168 h of treatments. Recombinant Bacillus thuringiensis was more effective as biocontrol agents against lepidopteran pests at the early instars, because susceptibility was decreased with larval development. This indicated that the first instars were more susceptible to Bt sprayed plants than the later instar stages. The combined effects of crystals + endospores produced higher mortality. This factor was important to be considered in designing resistance management strategies.

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Effects of chlorantraniliprole on development and reproduction of beet armyworm, Spodoptera exigua (Hübner)

Lai

2011

J Pest Sci

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The lethal and sublethal effects of chlorantraniliprole against Spodoptera exigua (Hübner) were evaluated under laboratory conditions by oral exposure of neonate larvae to the compound. The 72 h LC 50 value of this insecticide to S. exigua was found to be 12.747 lg l -1 . A progressive larval mortality of 24.32% for LC 30 treatment and 42.61% for LC 50 treatment was observed from 4th to 6th day after exposure, which resulted in the reduced pupation rates in exposure groups. The sublethal effects of this chemical were indicated by prolongation of larval period, the increase of pupal weight and decrease in hatch rate of egg. Chlorantraniliprole at LC 30 and LC 50 rate significantly delayed larval development; the developmental duration of surviving larvae was extended for 22.5 and 28.6%, respectively, compared with that of control group. LC 30 treatment increased the mean weight of pupa and induced to the production of heavier pupa ([150 mg). In LC 50 treatment, heavier pupa also showed up but the mean weight of pupa was not influenced. The egg hatch rate in LC 50 group was significant lower than that in control and LC 30 groups. No significant differences in pupal duration, emergence rate, sex ratio, egg number per female, and longevity of adults were observed among treatments. Chlorantraniliprole had exceptional activity against S. exigua according to concentration-response bioassay in laboratory, and the toxicities were primarily resulted from immediate lethality.

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Lethal and Sublethal Effects of Single and Double Applications of <I>Bacillus thuringiensis</I> Variety <I>kurstaki</I> on Spruce Budworm (Lepidoptera: Tortricidae) Larvae

Cited by 12 publications

References 23 publications

The Impact of Moth Migration on Apparent Fecundity Overwhelms Mating Disruption as a Method to Manage Spruce Budworm Populations

The Impact of Moth Migration on Apparent Fecundity Overwhelms Mating Disruption as a Method to Manage Spruce Budworm Populations

Mortality Responses of Spodoptera litura Following Feeding on BT- Sprayed Plants

Effects of chlorantraniliprole on development and reproduction of beet armyworm, Spodoptera exigua (Hübner)

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