Management of Tobacco Budworm, Heliothis Virescens (F.) and Bollworm, Helicoverpa Zea (Boddie) in Cotton: Host Plant Resistance and Ovicidal Approaches.

Growth, development and survival of pyrethroid-resistant (PY-R) and -susceptible (PY-S and FIELD-88) tobacco budworm, Heliothis virescens (F.), and bollworm (CORN-BW), Helicoverpa zea (Boddie), were compared on four cotton lines (\u27Deltapine 41\u27, La. HG-660, La. HG-063 and PD-0804) and artificial diet. The FIELD-88 and CORN-BW strains had significantly higher 5 and 9 day larval weights compared to the PY-R and PY-S laboratory strains. Larvae fed squares of La. HG-660 and La. HG-063 had significantly lower larval and pupal weights, required significantly more days to pupate and had higher cumulative mortality compared to those reared on squares of a commercial cultivar, Deltapine 41. In a field trial conducted during 1988 to evaluate advanced cotton lines and insecticide treatments against tobacco budworm and bollworm, no significant interaction was observed. However, La. HG-660 reduced larval infestations and damage, matured earlier and had comparable yields to DPL 41. Lint turnout and boll weight was lower for La. HG-660 than that for Deltapine 41. No significant differences were found among treatments in fiber length, micronaire and fiber strength of cotton samples. The toxicity of insecticides to eggs of PY-R, PY-S and field (FIELD-89) tobacco budworm strains was determined in laboratory tests. LC\sb{50}\u27s for all insecticides except profenofos on eggs of the PY-R strain were significantly higher than LC\sb{50}\u27s for the same insecticide on eggs of the PY-S strain. All insecticides except profenofos and methomyl were significantly more toxic to eggs of the PY-S strain compared to their respective toxicity to eggs of the FIELD-89 strain. Eggs of the PY-R strain exhibited resistance to esfenvalerate, lambda-cyhalothrin, and chlordimeform while eggs of the FIELD-89 strain possessed resistance to lambda-cyhalothrin, chlordimeform and SN 49844. In field tests conducted during 1987-1989, all insecticide treatments except methomyl (0.0071 kg (AI) /ha) and profenofos (0.56 kg (AI) /ha) exhibited initial ovicidal activity in one or more trials. The formamidines (amitraz and SN 49844) and a carbamate (thiodicarb) at 0.28 kg (AI) /ha generally exhibited residual ovicidal activity comparable to that of chlordimeform at 0.28 kg (AI) /ha

Pest population dynamics are related to a continental overwintering gradient

Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests

Pest population dynamics are related to a continental overwintering gradient

Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests

Pest population dynamics are related to a continental overwintering gradient

Overwintering success is an important determinant of arthropod populations that must be considered as climate change continues to influence the spatiotemporal population dynamics of agricultural pests. Using a long-term monitoring database and biologically relevant overwintering zones, we modeled the annual and seasonal population dynamics of a common pest, Helicoverpa zea (Boddie), based on three overwintering suitability zones throughout North America using four decades of soil temperatures: the southern range (able to persist through winter), transitional zone (uncertain overwintering survivorship), and northern limits (unable to survive winter). Our model indicates H. zea population dynamics are hierarchically structured with continental-level effects that are partitioned into three geographic zones. Seasonal populations were initially detected in the southern range, where they experienced multiple large population peaks. All three zones experienced a final peak between late July (southern range) and mid-August to mid-September (transitional zone and northern limits). The southern range expanded by 3% since 1981 and is projected to increase by twofold by 2099 but the areas of other zones are expected to decrease in the future. These changes suggest larger populations may persist at higher latitudes in the future due to reduced low-temperature lethal events during winter. Because H. zea is a highly migratory pest, predicting when populations accumulate in one region can inform synchronous or lagged population development in other regions. We show the value of combining long-term datasets, remotely sensed data, and laboratory findings to inform forecasting of insect pests