A Maximum Dose Bioassay to Assess Efficacy of Key Insecticides Against Bemisia tabaci MEAM1 (Hemiptera: Aleyrodidae)

2021 ◽  
Author(s):  
Bruno Rossitto De Marchi ◽  
Hugh Smith ◽  
William Turechek ◽  
David Riley
Keyword(s):  
Bemisia Tabaci ◽  
Maximum Dose ◽  
Petri Dish ◽  
South Florida ◽  
Insecticide Efficacy ◽  
Dose Curve ◽  
Laboratory Colony ◽  
Weed Hosts ◽  
Different Populations

Abstract The whitefly, Bemisia tabaci MEAM1 Gennadius causes serious losses to Florida vegetable and ornamental production. In 2019, a maximum dose bioassay was administered to 20 field populations of B. tabaci MEAM1 collected from various economic and weed hosts across south Florida to assess insecticide efficacy. The maximum dose bioassay tests the top labeled rate of the insecticide against B. tabaci adults on treated cotton leaves in a Petri dish over a 72-h period. A susceptible laboratory colony of B. tabaci MEAM1 and a colony of B. tabaci MED were also tested. Survival over 72 h was used to produce an area under the maximum dose curve, which was used to compare insecticide effects on different populations. Overall, imidacloprid demonstrated the poorest efficacy, dinotefuran and flupyradifurone were the most effective, and bifenthrin, cyantraniliprole, and thiamethoxam tended to group together, providing intermediate control. Across populations tested, survival in whitefly adults treated with dinotefuran was 50% lower than whiteflies treated with imidacloprid, about 33% lower than whiteflies treated with thiamethoxam, bifenthrin, and cyantraniliprole, and 10% lower than whiteflies treated with flupyradifurone. Efficacy of bifenthrin was less than imidacloprid on some populations, particularly from the Homestead area. Imidacloprid and thiamethoxam had no effect on mortality of the MED population when it was tested after 22 mo in culture without exposure to insecticides, although 7 mo later, these materials resulted in some mortality for the MED population.

scholarly journals Laboratory Evaluation of a Neem Product Against DBM Larvae, 1995

1997 ◽  
Vol 22 (1) ◽  
pp. 409-409
Author(s):  
R.F.L. Mau ◽  
L. R. Gusukuma-Minuto
Keyword(s):  
Petri Dish ◽  
Seedling Stage ◽  
Laboratory Evaluation ◽  
Complete Coverage ◽  
Plastic Petri Dish ◽  
True Leaf ◽  
Laboratory Colony ◽  
Treated Plant ◽  
Head Cabbage

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot containing approximately 10 cabbage plants in the 5 true leaf seedling stage was inverted and dipped in a test insecticide mix for about 30 sees for complete coverage. The dipped plants were allowed to air dry. For each dip, 1 liter insecticide mix was prepared based on field rate concentrations of 100 gal/acre. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten late 2nd instars were placed on each leaf. Fresh leaves from the original treated plant were added every two days. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed.

Testing mate recognition through reciprocal crosses of two native populations of the whitefly Bemisia tabaci (Gennadius) in Australia

2019 ◽  
Vol 110 (3) ◽  
pp. 328-339 ◽  
Author(s):  
W. Wongnikong ◽  
S. L. van Brunschot ◽  
J. P. Hereward ◽  
P. J. De Barro ◽  
G. H. Walter
Keyword(s):  
Bemisia Tabaci ◽  
Critical Role ◽  
Mate Recognition ◽  
Distinct Species ◽  
Species Status ◽  
Female Progeny ◽  
Native Populations ◽  
Different Populations ◽  
The Individual ◽  
Mating Tests

AbstractBemisia tabaci (Gennadius) represents a relatively large cryptic species complex. Australia has at least two native populations of B. tabaci sensu lato and these were first found on different host plants in different parts of Australia. The species status of these populations has not been resolved, although their mitochondrial sequences differ by 3.82–4.20%. We addressed the question of whether these AUSI and AUSII B. tabaci populations are distinct species. We used reciprocal cross-mating tests to establish whether the insects from these different populations recognize one another as potential mating partners. The results show that the two native Australian populations of B. tabaci have a mating sequence with four phases, each of which is described. Not all pairs in the control crosses mated and the frequency of mating differed across them. Some pairs in the AUSI-M × AUSII-F did mate (15%) and did produce female progeny, but the frequency was extremely low relative to controls. Microsatellite genotyping of the female progeny produced in the crosses showed these matings were successful. None of the AUSII-M × AUSI-F crosses mated although some of the males did search for females. These results demonstrate the critical role of the mate recognition process and the need to assess this directly in cross-mating tests if the species status of different populations is to be tested realistically. In short, AUSI and AUSII B. tabaci populations are distinct species because the individual males and females do not recognize individuals of the alternative population as potential mating partners.

scholarly journals Laboratory Evaluation of Two IGR Insecticides Against DBM Larvae, 1995

1997 ◽  
Vol 22 (1) ◽  
pp. 411-411
Author(s):  
R.F.L. Mau ◽  
L. R. Gusukuma-Minuto
Keyword(s):  
Petri Dish ◽  
Seedling Stage ◽  
Test Material ◽  
Laboratory Evaluation ◽  
Complete Coverage ◽  
Plastic Petri Dish ◽  
True Leaf ◽  
Laboratory Colony ◽  
Previously Treated ◽  
Head Cabbage

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot containing approximately 10 cabbage plants in the 5-7 true leaf seedling stage was inverted and dipped in a solution of the test materials for about 30 sees for complete coverage. The dipped plants were allowed to air dry. For each dip, 1 liter solution of the test material was prepared based on field rate concentrations of 100 gal/acre. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten 2nd instars were placed on each leaf. Each treatment was replicated 10 times. Xentari was used as the treated check. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed. Leaves were changed every other day with fresh leaves from the previously treated pots.

scholarly journals Germination of coastalplain honeycombhead (Balduina angustifolia) in response to photoperiod, temperature and gibberellic acid

2021 ◽  
Author(s):  
Gabriel Campbell-Martínez ◽  
Mack Thetford ◽  
Sandra B. Wilson ◽  
Carlee Steppe ◽  
Héctor E. Pérez ◽  
...  
Keyword(s):  
Gibberellic Acid ◽  
Regional Scale ◽  
South Florida ◽  
Source Population ◽  
Central Florida ◽  
South Central ◽  
Different Populations ◽  
Conservation Projects ◽  
One Year ◽  
Northwest Florida

Coastalplain honeycombhead (Balduina angustifolia) is underutilised in ecosystem restoration and pollinator conservation projects. Seeds collected from different populations throughout Florida, USA during 2007 and 2016-2018 were used in experiments that evaluated the effects of a 0 or 12-hour photoperiod, seasonal and standard temperatures, 0-5,000 ppm gibberellic acid (GA) or source population (northwest, central and south Florida) on seed germination. For central Florida seeds, germination was high (62-74%) in all seasonal temperatures except for summer (4%) and was not affected by photoperiod. Germination differed for two northwest populations and was higher in warm (35/25 and 30/20°C) temperatures compared with cool (25/15 and 20/10°C) temperatures (63-72% vs. 9-36%). In a one-year move-along experiment, germination was similar at all seasonal and constant temperatures for seeds from central, south-central and south Florida, while northwest Florida seeds had reduced germination under winter temperatures. Germination of northwest Florida seeds after exposure to GA increased for two of four and three of four populations for one year and five-day old seeds, respectively. There were different temperature requirements on a regional scale and different dormancy levels at a local scale for coastalplain honeycombhead.

Ultraviolet germicidal irradiation disinfection of Stachybotrys chartarum

2005 ◽  
Vol 51 (9) ◽  
pp. 801-804 ◽  
Author(s):  
Christopher F Green ◽  
Craig S Davidson ◽  
Pasquale V Scarpino ◽  
Shawn G Gibbs
Keyword(s):  
Maximum Dose ◽  
Fungal Spores ◽  
Petri Dish ◽  
Stachybotrys Chartarum ◽  
Surface Dose ◽  
Ultraviolet Germicidal Irradiation ◽  
Airborne Fungal Spores ◽  
Dose Ranging ◽  
Agar Surface ◽  
Higher Doses

The ultraviolet germicidal irradiation (UVGI) dose necessary to inactivate fungal spores on an agar surface and the efficacy of UVGI were determined for cultures of Stachybotrys chartarum (ATCC 208877). This study employed a UVGI testing unit consisting of four chambers with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber. The testing unit's apertures were adjusted to provide 50, 100, 150, and 200 µW/cm2 of uniform flux to the Petri dish surfaces, resulting in a total UVGI surface dose ranging from 12 to 144 mJ/cm2. The UVGI dose necessary to inactivate 90% of the S. chartarum was greater than the maximum dose of 144 mJ/cm2 evaluated in this study. While UVGI has been used to inactivate several strains of culturable fungal spores, S. chartarum was not susceptible to an appropriate dose of UVGI. The results of this study may not correlate directly to the effect of UVGI on airborne fungal spores. However, they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores, such as S. chartarum, traveling through the irradiated zone.Key words: Stachybotrys chartarum (synonyms S. atra, S. alternana), ultraviolet germicidal irradiation, fungi.

scholarly journals Laboratory Evaluations of Bioinsecticides Against Dbm Larvae, 1994

1995 ◽  
Vol 20 (1) ◽  
pp. 327-327
Author(s):  
R. F. L. Mau ◽  
L. R. Gusukuma-Minuto ◽  
R. S. Shimabuku
Keyword(s):  
Petri Dish ◽  
Seedling Stage ◽  
Complete Coverage ◽  
Plastic Petri Dish ◽  
True Leaf ◽  
Laboratory Colony ◽  
Treated Plant ◽  
Newly Hatched Larvae ◽  
Head Cabbage ◽  
Respective Solution

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot contained approximately 10 cabbage plants. Potted head cabbage in the 5 true leaf seedling stage were dipped in each respective solution for complete coverage and allowed to air dry. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii were used. Ten newly hatched larvae were placed on each leaf. Fresh leaves from the original treated plant were added every two days. The number of dead larvae was counted at 24 or 48 hour intervals. Larvae were recorded as dead when there was no movement when probed.

scholarly journals Bacterial Endosymbiont Diversity among Bemisia tabaci (Hemiptera: Aleyrodidae) Populations in Florida

Insects ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 179 ◽  
Author(s):  
Bruno Rossitto De Marchi ◽  
Hugh A. Smith
Keyword(s):  
Phylogenetic Analysis ◽  
Bemisia Tabaci ◽  
Virus Transmission ◽  
Plant Viruses ◽  
Transmission Efficiency ◽  
South Florida ◽  
Sweetpotato Whitefly ◽  
Low Genetic Diversity ◽  
Bacterial Endosymbionts

The sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a pest of many economically important agricultural crops and a vector of plant viruses. Bemisia tabaci harbors facultative endosymbiont species that have been implicated in pest status, including tolerance to insecticides, virus transmission efficiency and tolerance to high-temperatures. The facultative endosymbionts reported in B. tabaci include Arsenophonus, Hamiltonella, Wolbachia, Cardinium, Fritschea and Rickettsia. We collected whitefly populations from weed and crop hosts in south Florida and identified the whitefly species as well as the facultative endosymbionts present in these populations by molecular analysis. In addition, a phylogenetic analysis of whiteflies and their endosymbionts was performed. The only facultative endosymbionts found among the B. tabaci populations collected in Florida were Hamiltonella and Rickettsia. The phylogenetic analysis revealed the low genetic diversity of whiteflies and their endosymbionts. Additionally, the phylogenetic tree clustered Rickettsia from Florida in the R1 genetic group. The results will aid to understand the role of the bacterial endosymbionts in the whitefly host.

scholarly journals Regional Survey of Diamondback Moth (Lepidoptera: Plutellidae) Response to Maximum Dosages of Insecticides in Georgia and Florida

2020 ◽  
Vol 113 (5) ◽  
pp. 2458-2464
Author(s):  
David Riley ◽  
Hugh Smith ◽  
John Bennett ◽  
Philip Torrance ◽  
Evan Huffman ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Maximum Dose ◽  
Diamondback Moth ◽  
Resistance Management ◽  
Regional Survey ◽  
Insecticide Efficacy ◽  
Action Committee ◽  
Lambda Cyhalothrin ◽  
Rapid Bioassay ◽  
Low Levels

Abstract We conducted maximum dose bioassays of insecticide for the control of diamondback moth (DBM), Plutella xylostella (Linnaeus), in cole crops, from 2016 to 2019 at several commercial locations in Georgia and Florida. The nominal maximum dose was defined as the highest labeled rate of an insecticide at the beginning of the survey in the equivalent of 935 liters/ha dilution. The results indicated low insecticide efficacy for high labeled rates of the following insecticides by common name (Insecticide Resistance Action Committee group number in parentheses). Our 4-yr survey identified very low levels of DBM larval control (<47%) by lambda-cyhalothrin (3), methoxyfenozide (18), pyriproxyfen (7C), novaluron (15), bifenthrin (3), chlorantraniliprole (28), indoxacarb (22A), and methomyl (1A). The best products for DBM control (>74%) listed in decreasing average levels of efficacy were naled (1B), cyclaniliprole (28), tolfenpyrad (21A), emamectin benzoate (6), and cyantraniliprole (28). Intermediate levels of control (61–71%) were obtained with Bacillus thuringiensis subspecies aizawai (11A), Bacillus thuringiensis, subsp. kurstaki, strain ABTS-351 (11A), and spinetoram (5). This rapid bioassay provided the grower with a ranking of insecticide efficacy for the control the DBM population for that farm site. These data allowed growers to make an informed decision on control quickly and plan for resistance management rotations for DBM that season.

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