Roy E. McLaughlin

Isolation of a protein from the parasporal crystal of Bacillus thuringiensis var, kurstaki toxic to the mosquito larva, Aedes taeniorhynchus☆

The parasporal crystal produced by a strain of Bacillus thuringiensis var. kurstaki (HD-1) contains two serologically distinct proteins. These proteins were isolated from a preparation of the parasporal crystal by Sephacryl S-300 column chromatography. Their molecular weights were estimated as 135,000 and 65,000. Both proteins were toxic to the cabbage looper, Trichoplusia ni, but only the 65,000-dalton protein was toxic to larvae of the mosquito, Aedes taeniorhynchus. Biochemical comparisons based on isoelectric focusing and peptide mapping by two-dimensional gel electrophoresis indicated that the two toxins were distinctly different.

Infection of the boll weevil by Chilo iridescent virus

Abstract When infections with Chilo iridescent virus (CIV) were induced in larvae of boll weevils, Anthonomus grandis , by intrahemocoelic injection or by feeding, and in adults by feeding, the typical blue coloration of adipose tissue developed at 3–7 days postinfection, and mortality occurred after 3 days. The symptomatology and the pathological expressions depended on the initial infectious titer. The virus remained viable when it was added to the feeding stimulant bait used to infect weevils with protozoan pathogens in the field, and weevils feeding on the formulation became infected when it had been exposed 1–3 days in nature.

Development of the bait principle for boll-weevil control: II. Field-cage tests with a feeding stimulant and the protozoan Mattesia grandis

Abstract A formulation containing spores of the protozoan Mattesia grandis and a feeding stimulant made from cottonseed oil and a water extract of contton squares plus carrier materials and a marking dye was tested against a population of the boll weevil, Anthonomus grandis, on cotton in 1 16 - acre field cages. Effectiveness of the formulation was judged by the percentage of marked weevils and the incidence of disease among adults collected at the end of the test. Twenty to 30% of the treated population was marked during the main fruiting period, which is also the period of rapid development of the boll-weevil population, and 50% to 60% during the latter part of the test when the plants were maturing and fewer weevils were developing because of cooler temperatures. At the end of the test, 55% of the weevils were diseased. The diseased population producd about half as many adults as the check population. The treated adult population remained stabilized; the check had sharply defined, eruptive increases in number of adults as each generation emerged from squares or bolls. A feeding stimulant with spores or other effective agents might be effective in reducing populations in large open fields.

Mass production in vivo of two protozoan pathogens, Mattesia grandis and Glugea gasti, of the boll weevil, Anthonomus grandis

A method is described for production in vivo of large amounts of spores of Mattesia grandis and Glugea gasti, both sporozoan pathogens of the boll weevil, Anthonomus grandis. Boll weevil larvae obtained from the mass-rearing section of our laboratory, growing in artificial diet in petri dishes, are inoculated with spores. An optimum spore dose and larval age at time of inoculation exists for each pathogen. Infected adults emerge, live a short time, and are harvested for optimum spore production. Production of the two pathogens is compared, with Glugea gasti producing more spores per insect and thus having a much lower cost. The method shows that mass production in vivo of a protozoan pathogen can be done when large numbers of the host insect can be economically grown. The pathogens were produced to support 5 years of field testing.

Development of the bait principle for boll weevil control IV. Field tests with a bait containing a feeding stimulant and the sporozoans Glugea gasti and Mattesia grandis

Abstract Bait containing feeding stimulant and one of two protozoan pathogens ( Mattesia grandis or Glugea gasti ) was tested against field populations of boll weevils ( Anthonomus grandis ) in the fall of 1966 throughout the season in 1967. In 1966, the weevils that subsequently diapaused responded well to the bait since 60–80% had ingested the red marker dye. Also, although the quantity of the pathogen was limited, both diseases were found in the populations. In 1967, 50–70% of the weevil population present in late June and early July (overwintered weevils) ingested bait containing G. gasti , and as many as 80% were diseased. In contrast, the F 1 and ensuing reproducing generations present from mid-July through August did not respond well: only 2–19% were marked, and only 11–25% were diseased. Then after August 31, as the weevils began to enter diapause, the population again responded well, and 50–70% were marked and diseased. Also, over 60% of the weevils subsequently collected from woods trash from winter hibernation sites were marked and diseased. The treatment with the pathogens in 1967 caused 96% winter mortality of boll weevils compared with 84% in nearby untreated areas. In addition, large populations of insect predators were found in the treated area, and several gallons of one species were collected in samples of woods trash examined in April 1968.

Observations of boll weevil midgut when fed natural food or on bacterially contaminated artificial diet

Abstract Boll weevils fed natural food had normal midgut morphology, but weevils fed bacterially contaminated artificial diet had deteriorated midguts which became progressively less functional with continued feeding on the diet. Reversal of the conditions occurred when the weevils were returned to natural food. This recovery did not take place, however, if the deterioration was too advanced. All strains of boll weevils had similar midgut responses. Cellular destruction in the midgut and loss of tissue function led to typical symptoms of starvation and desiccation during the first 10 days of adult life. Continued feeding upon contaminated food resulted in premature death. These observations show the importance of sanitation in mass-rearing procedures. It also may provide an explanation for subnormal boll weevil quality as reported by other authors who measured longevity, pheromone, and fatty acid production.

Development of the bait principle for boll-weevil control: III. Field-cage tests with a feeding stimulant and the protozoans Mattesia grandis (neogregarinida) and a microsporidian

Abstract When Mattesia grandis or a microsporidian were incorporated into a bait containing a feeding stimulant and a marker dye, and tested for suppression of a caged population of the boll weevil, Anthonomus grandis , about 30–40% of the adults fed on the bait. However, rain prevented continuous and optimum coverage of the plants with the bait. Both pathogens suppressed the populations of weevils, thus producing a further demonstration of the validity of the principle of using responseeliciting materials in a bait containing a pathogen to induce disease.

Free-Swimming Colonial Rotifers (Monogononta:Flosculariacea:Flosculariidae) in Southwestern Louisiana Rice Fields

During the summer of 1984, free-swimming colonial rotifers were collected incidental to field studies on mosquitoes in 335 rice fields in southwestern Louisiana. Six of the seven known species of free-swimming colonial flosculariid rotifers were found: Lacinularia elliptica Shepard, L. flosculosa (Mueller), L. ismailoviensis (Poggenpol), Sinantherina semibullata (Thorpe), S. socialis (Linnaeus) and S. spinosa (Thorpe). Lacinularia causeyae n. sp., a species new to science, was collected and is described herein. Of the 335 fields sampled, 225 fields had at least one species of these rotifers, which were locally abundant. Estimates of relative abundance are presented.

Some relationships between the boll weevil, Anthonomus grandis Boheman, and Mattesia grandis McLaughlin (Protozoa: Neogregarinida)☆

Abstract The neogregarine, Mattesia grandis McLaughlin, infects larvae and adults of the boll weevil, Anthonomus grandis Boheman, when the spores are ingested; larvae, pupae, and adults are susceptible. Sporogony and production of free spores usually occurred 7 days after infection. Development of the pathogen was retarded in adults when little or no lipoid material was deposited in the adipose tissue, but normal development resumed when the adult diet was altered to result in deposition of fat. The rate of development of the pathogen also appeared to vary directly with temperature changes. Infected female weevils laid fewer eggs per day than healthy females.

Bacteria and fungi associated with dead boll weevils (Anthonomus grandis) in a natural population

Abstract An unusually large number of dead boll weevils (Anthonomus grandis) were found covered by a pinkish-white external fungus and adhering to unopened cotton bolls in an experimental cotton field in Self Creek Community, Oktibbeha County, Mississippi, in October and November 1964. A study was made of the dead weevils, and all bacteria and fungi present internally were isolated. These cultures were identified, and representatives from taxonomic groups were tested for pathogenicity. Cloaca A (Aerobacter cloacae; Enterobacter cloacae) occurred most frequently. Other bacterial isolates with similar characteristics did not fit currently recognized groups of the Enterobacteriaceae but were similar in some respects to Cloaca A, Serratia, and an Intermediate group. Other genera represented were Pseudomonas, Alcaligenes, Achromobacter, Klebsiella, Lactobacillus, and Bacillus. The most frequently isolated fungi belonged to the genus Fusarium. Other fungi represented were Fusidium sp., Oedocephalum sp., Aspergillus sp., and Penicillium sp. No microorganisms tested were pathogenic. The bacteria were considered normal flora of the weevil intestinal tract, and their frequent occurrence indicated that Cloaca A and the Intermediate group were often either present in the living host or possessed special ability to grow after host death to the exclusion of other bacteria, or both. The frequent occurrence of Fusarium fungi indicated that the fungi possessed certain characteristics which permitted exclusive saprophytic growth.