Jacqueline L. Robertson

Bemisia: Bionomics and Management of a Global Pest

This is the most informative compilation I have ever read. The original workshop took place in 2006, and all information was updated to produce the book. Worldwide outbreaks of Bemisia in the past 25 yr have been economically devastating. In the future, we can expect this trend to continue, especially with the spread of insecticide-resistant biotype Q. I read about whiteflies in the context of pesticide resistance and tolerance but had no idea how quickly an insect species can evolve. (When you do …

Comparative Toxicities and Synergism of Apple Orchard Pesticides to Apis mellifera (L.) and Osmia cornifrons (Radoszkowski)

The topical toxicities of five commercial grade pesticides commonly sprayed in apple orchards were estimated on adult worker honey bees, Apis mellifera (L.) (Hymenoptera: Apidae) and Japanese orchard bees, Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae). The pesticides were acetamiprid (Assail 30SG), λ-cyhalothrin (Warrior II), dimethoate (Dimethoate 4EC), phosmet (Imidan 70W), and imidacloprid (Provado 1.6F). At least 5 doses of each chemical, diluted in distilled water, were applied to freshly-eclosed adult bees. Mortality was assessed after 48 hr. Dose-mortality regressions were analyzed by probit analysis to test the hypotheses of parallelism and equality by likelihood ratio tests. For A. mellifera, the decreasing order of toxicity at LD50 was imidacloprid, λ-cyhalothrin, dimethoate, phosmet, and acetamiprid. For O. cornifrons, the decreasing order of toxicity at LD50 was dimethoate, λ-cyhalothrin, imidacloprid, acetamiprid, and phosmet. Interaction of imidacloprid or acetamiprid with the fungicide fenbuconazole (Indar 2F) was also tested in a 1∶1 proportion for each species. Estimates of response parameters for each mixture component applied to each species were compared with dose-response data for each mixture in statistical tests of the hypothesis of independent joint action. For each mixture, the interaction of fenbuconazole (a material non-toxic to both species) was significant and positive along the entire line for the pesticide. Our results clearly show that responses of A. mellifera cannot be extrapolated to responses of O.cornifrons, and that synergism of neonicotinoid insecticides and fungicides occurs using formulated product in mixtures as they are commonly applied in apple orchards.

METABOLIC BASIS OF DIFFERENTIAL SUSCEPTIBILITY OF TWO FOREST LEPIDOPTERANS TO DIFLUBENZURON

Sixth instar Choristoneura occidentalis Freeman and 5th instar Orgyia pseudotsugata (McDunnough) were fed ring‐labelled 14C‐diflubenzuron coated on Douglas‐fir needles. After ingestion the gut was purged of radioactive needle residues with artificial diet. Radioactivity in body and frass extracts and residues were measured. Diflubenzuron in extracts were separated from metabolites by thin layer chromatography.

Possible physiological mechanisms for the differential susceptibility of two forest Lepidoptera to diflubenzuron

Abstract In an attempt to explain the physiological mechanisms for the differential susceptibility of insects to the chitin synthesis inhibitor, diflubenzuron, chitin content, chitin synthesis, and retention of ingested 14 C-diflubenzuron in two forest Lepidoptera were investigated. The spruce budworm, Choristoneura fumiferana , a refractory species, had less chitin and retained less of the ingested material than the forest tent caterpillar, Malacosoma disstria , a species highly sensitive to diflubenzuron. No difference in the chitin synthesis pattern during the 6th stadium was observed in the two species. It is concluded that the primary reasons for the increased susceptibility of the forest tent caterpillar to this compound was the increased retention of ingested diflubenzuron and, to a lesser extent, the increased chitin content.

Chilled Galleria mellonella: Salivary glands may mechanically inhibit development☆

Abstract The possible role of the stiffened salivary glands in inhibiting metamorphosis of last-instar chilled Galleria mellonella was explored. Inhibitory effects of chilling on the salivary glands and delayed development of the whole animal were clearly correlated. In animals less than 3 days post-ecdysis, the salivary glands accounted for less than 4% of the total body weight; chilling these animals resulted in an increased number of supernumerary apolyses and accelerated developmental time. From 4 to 10 days post-ecdysis, when the salivary glands accounted for 5% or more of total body weight, chilling significantly delayed larval-pupal ecdysis. Reduction of the dimensions of the salivary glands by prior space deprivation significantly reduced the effects of chilling. Extirpation of the salivary glands eliminated the chill effect, whereas insertion of a 7 mm piece of tubing into the body mimicked the effect. These results suggest that chill-stiffened salivary glands may mechanically inhibit development.

LABORATORY EVALUATION OF PHOSALONE FOR CONTROL OF WESTERN SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

Phosalone was tested to estimate the optimal time and minimum application rate for 90% population mortality of western spruce budworm, Choristoneura occidentalis Freeman, larvae. The optimal time o...

XRD-473 (AN EXPERIMENTAL BENZOYLPHENYLUREA): RATES AND OPTIMAL TIME OF APPLICATION TO WESTERN SPRUCE BUDWORM

XRD-473 (N-(((3,5-Dichloro-4-(1,1,2,2-tetrafluoroethoxy) phenyl-amino) carbonyl)-2, 6-difluorobenzamide), a benzoylphenylurea (BPU), was tested in a series of experiments to estimate the optimal ti...