scholarly journals Bifenthrin Baseline Susceptibility and Evaluation of Simulated Aerial Applications in Striacosta albicosta (Lepidoptera: Noctuidae)

2019 ◽  
Vol 112 (6) ◽  
pp. 2915-2922
Author(s):  
Débora G Montezano ◽  
Thomas E Hunt ◽  
Dariane Souza ◽  
Bruno C Vieira ◽  
Ana M Vélez ◽  
...  
Keyword(s):  
Active Ingredient ◽  
Resistance Management ◽  
Eastern United States ◽  
Spray Chamber ◽  
Aerial Application ◽  
Natural Behavior ◽  
Striacosta Albicosta ◽  
Lepidoptera Noctuidae ◽  
Control Failures ◽  
Field Failure

Abstract Striacosta albicosta (Smith) is a maize pest that has recently expanded its geographical range into the eastern United States and southeastern Canada. Aerial application of pyrethroids, such as bifenthrin, has been a major practice adopted to manage this pest. Reports of field failure of pyrethroids have increased since 2013. Striacosta albicosta populations were collected in 2016 and 2017 from maize fields in Nebraska, Kansas, and Canada and screened with bifenthrin active ingredient in larval contact dose-response bioassays. Resistance ratios estimated were generally low in 2016 (1.04- to 1.32-fold) with the highest LC50 in North Platte, NE (66.10 ng/cm2) and lowest in Scottsbluff, NE (50.10 ng/cm2). In 2017, O’Neill, NE showed the highest LC50 (100.66 ng/cm2) and Delhi, Canada exhibited the lowest (6.33 ng/cm2), resulting in a resistance ratio variation of 6.02- to 15.90-fold. Implications of bifenthrin resistance levels were further investigated by aerial application simulations. Experiments were conducted with a spray chamber where representative S. albicosta populations were exposed to labeled rates of a commercial bifenthrin formulation. Experiments resulted in 100% mortality for all populations, instars, insecticide rates, and carrier volumes, suggesting that levels of resistance estimated for bifenthrin active ingredient did not seem to impact the efficacy of the correspondent commercial product under controlled conditions. Results obtained from this research indicate that control failures reported in Nebraska could be associated with factors other than insecticide resistance, such as issues with the application technique, environmental conditions during and/or after application, or the insect’s natural behavior. Data generated will assist future S. albicosta resistance management programs.

Susceptibility of Different Instars of Striacosta albicosta (Lepidoptera: Noctuidae) to Vip3A, a Bacillus thuringiensis (Bacillaceae: Bacillales) Protein

2019 ◽  
Vol 112 (5) ◽  
pp. 2335-2344 ◽  
Author(s):  
Yasmine Farhan ◽  
Jocelyn L Smith ◽  
Arthur W Schaafsma
Keyword(s):  
Bacillus Thuringiensis ◽  
Resistance Management ◽  
High Dose ◽  
Transgenic Corn ◽  
Resistance Development ◽  
Significant Difference ◽  
Survival And Development ◽  
Important Pest ◽  
Striacosta Albicosta ◽  
Lepidoptera Noctuidae

Abstract Striacosta albicosta (Smith) (Lepidoptera: Noctuidae) is an important pest of corn, Zea mays L. in the Great Lakes region, which can be controlled by transgenic corn expressing Vip3A protein from Bacillus thuringiensis. To inform insect resistance management, the susceptibility, survival, and development of first, third, and fifth instar S. albicosta to Vip3A was determined using protein-overlay and corn tissue bioassays. Tissue bioassays were also used to determine the quantity of corn tissues with and without Vip3A-expression consumed by various instars. In diet bioassays, third and fifth instars were significantly less susceptible to Vip3A compared with first instars; however, no significant difference was observed in susceptibility of older instars. In tissue bioassays, survival was lowest for larvae fed Vip3A-expressing tissues, ranging from 0 to 21%, however, developmental measures of larvae fed Vip3A-expressing tissues did not differ from those fed artificial diet or tissues of other Bt events. Consumption of Vip3A × Cry1Ab tissues did not differ from that of Cry1Ab for each instar. Estimated Vip3A exposure of first instars ranged from 3 to 57 times higher than the concentration required for 99% mortality (LC99) based on the product of the reported Vip3A expression in transgenic corn tissues and the consumption observed in tissue bioassays; however, the estimated exposure of third and fifth instars to Vip3A was lower than their respective LC99. These findings suggest that first instar S. albicosta maybe exposed to a high dose of Vip3A under field conditions; however, Vip3A-expression in corn may not be high dose against older instars, increasing the risk of resistance development.

Helicoverpa zea (Lepidoptera: Noctuidae) Preference for Plant Structures, and Their Location, Within Bt Cotton Under Different Nitrogen and Irrigation Regimes

2019 ◽  
Vol 112 (4) ◽  
pp. 1741-1751
Author(s):  
Lewis R Braswell ◽  
Dominic D Reisig ◽  
Clyde E Sorenson ◽  
Guy D Collins
Keyword(s):  
Helicoverpa Zea ◽  
Resistance Management ◽  
Larval Feeding ◽  
Bt Cotton ◽  
Larval Distribution ◽  
Cotton Plants ◽  
Small Plot ◽  
Nitrogen Treatments ◽  
Behavioral Resistance ◽  
Lepidoptera Noctuidae

Abstract Helicoverpa zea Boddie is a common economic pest of cotton (Gossypium hirsutum L.), including transgenic cotton varieties that express Bacillus thuringiensis (Bt). Helicoverpa zea oviposition is similar in Bt and non-Bt cotton, but behavior of H. zea larvae can be different in the presence of Bt, with neonates moving away from terminals faster in single-toxin Bt than non-Bt cotton or avoiding Bt-treated diet in the lab. We quantified H. zea oviposition and larval distribution on structures within cotton plants in small plot experiments of Cry1Ac + Cry1F cotton for 2 yr under different irrigation and nitrogen treatments. More eggs were oviposited on plants receiving nitrogen application during 2016 and on leaves in the top section of irrigated plants during 2017, but other treatment effects on eggs or larvae were minimal. Helicoverpa zea eggs were most common on leaves in the top third of plants at position zero and middle section of cotton plants throughout the season, but some oviposition occurred on fruiting structures as well. First and second instars were more common on squares in the top section of plants during 2016 and bolls in the middle and lower sections during 2017 due to oviposition lower in the canopy during 2017. During both years, third through fifth instars were more common on bolls in the middle and lower section of plants closer to the main stem. These findings have resistance management implications as extended larval feeding on bolls could optimize nutrition, decrease Bt susceptibility, and potentially influence behavioral resistance.

RELATIONSHIP BETWEEN MICROBIAL NUMBERS AND DROPLET SIZE IN AERIAL SPRAY APPLICATIONS

1977 ◽  
Vol 109 (10) ◽  
pp. 1319-1323 ◽  
Author(s):  
O. N. Morris
Keyword(s):  
Active Ingredient ◽  
Inclusion Bodies ◽  
Drop Size ◽  
Unit Area ◽  
Agar Plate ◽  
Ground Level ◽  
Aerial Application ◽  
Plate Method ◽  
The Relationship ◽  
Entomopathogenic Viruses

AbstractExperiments were designed to determine the actual number of spores and crystals of Bacillus thuringiensis (B.t.) and of nuclear polyhedral virus and entomopoxvirus deposited at ground level per unit area and to determine any change in spore:crystal ration following aerial application in forested plots.The results indicate that: (1) The estimation of B.t. aerial spray deposits by the commonly used agar plate method grossly underestimates the deposit rates of active ingredient. The tracer dye method more accurately estimates deposit rates for both B.t. and entomopathogenic viruses. As a dye 0.1% Erio Acid Red XB is recommended. (2) The relationship between drop size and the number of spores and crystals or virus inclusion bodies/drop is curvilinear. This relationship probably holds true regardless of spray volume rate. All visible spray deposits at ground level contained some active ingredient. (3) With B.t. sprays the sporexrystal ratio emitted from the aircraft is not changed upon target impact.

Communication disruption of adult Egyptian cotton leafworm Spodoptera littoralis (Boisd.) (Lepidoptera, Noctuidae) in Crete using synthetic pheromones applied by microencapsulation and dispenser techniques

1976 ◽  
Vol 66 (2) ◽  
pp. 335-344 ◽  
Author(s):  
D. G. Campion ◽  
L. J. McVeigh ◽  
J. Murlis ◽  
D. R. Hall ◽  
R. Lester ◽  
...  
Keyword(s):  
Active Ingredient ◽  
Spodoptera Littoralis ◽  
Inhibitory Effect ◽  
Unmated Female ◽  
North West ◽  
Communication Disruption ◽  
Clear Dose Response ◽  
High Level ◽  
Egyptian Cotton ◽  
Lepidoptera Noctuidae

AbstractCommunication between adult male and female Spodoptera littoralis (Boisd.) was disrupted by spraying microencapsulated formulations of pheromone inhibitor (IIA) (Z)-9-tetradecen-1-yl-acetate on lucerne plots in north-west Crete. Polyurea-based microcapsules applied at the rate of 100 g/ha active ingredient caused a 97% disruption for a period of seven days, as measured by the reduction of catches in the treated area in traps baited with the pheromone attractant (III) (Z)-9, (E)-11-tetradecadien-1-yl acetate, compared with catches in control areas. At lower rates of application both the level of disruption after seven days and the subsequent persistence of the effect were reduced. When applied at a rate of 100 g/ha active ingredient, disruption of 80% and above was achieved for a period of three weeks. Slower release microcapsules containing IIA based on polyurea/polyamide appeared more effective in that a level of disruption was achieved at one-tenth the amount of active ingredient required for the polyurea-based formulations.III dispensed in polythene vials caused 97% disruption when distributed at the rate of one vial per 9 m2, with lower levels of disruption at distributions of one vial per 25 m2 or 50 m2. IIA was much less effective in causing communication disruption at the same rates of distribution and no clear dose/response relationship was established.Inside enclosures of 10 100 and 1 000 m2 fenced by single-strand polythene impregnated with IIA at the rate of 1 mg/5 cm and maintained at a height of 0·5 m, a high level of disruption in excess of 93% was achieved for the first five days. The effect persisted in the smaller enclosures in that disruption in excess of 80% was maintained for a period of 40 days. In the 1 000 m2 enclosure the effect declined much more quickly.When IIA and III were dispensed together in WT traps the inhibitory effect persisted for at least 60 days. Similarly the polyurea-based microcapsules containing IIA together with III in WT traps maintained an inhibitory action for periods of 30–40 days. Polyurea/polyamide formulations of IIA were generally less effective, probably because loss from these slow releasing formulations became too low. Small numbers of mostly unmated female moths were attracted to the traps when IIA was exposed together with III, either when dispensed in the polythene vials or in microencapsulated formulations.

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