Diorhabda elongata (Brullé) sensu lato leaf beetles have been released in the United States for t... more Diorhabda elongata (Brullé) sensu lato leaf beetles have been released in the United States for the classical biological control of invasive Tamarix L. species, which are exotic trees that are causing deterioration of riparian ecosystems in western North America. The impact of D. elongata defoliation on Tamarix nonstructural carbohydrates (NCHOs) was measured in both manipulative field cage, and non-manipulative natural experiments. Additionally, spring above-ground growth was measured following beetle defoliation in manipulative field cage experiments in Texas. There was no significant difference in the proportional change in NCHOs between beetle-damaged and undamaged control-treatment trees in the manipulative field cage experiment. However, spring above-ground regrowth was reduced by 35% on trees which experienced beetle defoliation the previous fall. In the natural experiment, root crown tissue was sampled in 2005 and 2006 from stands near Lovelock, Nevada in which trees had experienced 0-4 years of beetle defoliation. In 2005, mean NCHO concentrations were statistically different between tree stands and ranged from 9.0 ± 0.8% (mean ± SE) in trees that had not been defoliated to 3.2 ± 0.4%, 2.1 ± 0.4% and 2.3 ± 0.4% in trees in stands that had been defoliated for 1, 2 and 3 successive years, respectively. In 2006, NCHO concentrations were again statistically different between stands and ranged from 13.6 ± 0.9% in trees that had not been defoliated to 7.6 ± 0.8%, 2.3 ± 0.4%, 1.5 ± 0.3% and 1.7 ± 0.4% in trees in stands that had been defoliated for 1, 2, 3 and 4 years, respectively. These results indicate that D. elongata herbivory reduces nonstructural carbohydrates and inhibits regrowth which may lead to reduced survival and reproduction of Tamarix.
... MARVIN HARRIS, I BILL REE, I JOHN COOPEH,2 JOHN JACKMAN,t JONI YOUNG, I HONAL]) LACEWELL,3 AN... more ... MARVIN HARRIS, I BILL REE, I JOHN COOPEH,2 JOHN JACKMAN,t JONI YOUNG, I HONAL]) LACEWELL,3 AND ALLEN KNUTSON4 ... Spraying in 1977used a hydraulic sprayer (at 1,871-2,807Iiters/ha) and, in subsequent years, a Savage model .500mist blower (at 1,207 ...
The cotton fleahopper, Pseudatomoscelis seriatus Reuter, is a widespread and important insect pes... more The cotton fleahopper, Pseudatomoscelis seriatus Reuter, is a widespread and important insect pest of cotton in Texas and Oklahoma. This plant bug feeds on small floral buds, which results in bud abscission, delayed fruiting, and subsequent crop loss. In central and southeastern Texas, two to four insecticide applications are typically applied for cotton fleahopper management. Primitive race stocks of cotton have been identified as an important source of resistance to a wide range of insect pests, but they have not been evaluated for resistance to cotton fleahopper. The objective of this study was to evaluate selected groups of primitive race stocks of Gossypium hirsutum L. for resistance to cotton fleahopper. Resistance was identified by caging cotton fleahoppers on cotton plants in a no-choice feeding trial and comparing the mean number of damaged squares per plant to a standard susceptible genotype. Four primitive race stocks, TX706, TX188, TX1530, and TX1156, were identified as ...
Sugarcane aphid Melanaphis sacchari Zehntner is a significant economic pest of grain sorghum in t... more Sugarcane aphid Melanaphis sacchari Zehntner is a significant economic pest of grain sorghum in the United States. Effective monitoring and early detection are cornerstones for managing invasive pests. The recently developed binomial sequential sampling plan estimates sugarcane aphid economic thresholds (ETs) based on classification whether a 2-leaf sample unit has ≤ or ≥ 50 M. sacchari. In this study, we evaluated eight 2-leaf sampling units for potential use in the sequential sampling plan. From 2016 through 2017, whole plant counts of M. sacchari were recorded non-destructively in situ on sorghum plants from 140 fields located in five states. Plant canopies were stratified into three categories. Two leaves from each stratum were used to compare linear relationships between M. sacchari numbers per two-leaf sample unit and total M. sacchari density per plant. Analysis revealed that two randomly selected leaves from the middle stratum accounted more variation for estimating M. sacch...
The cotton fleahopper, Pseudatomocelis seriatus (Reuter), is a major pest of cotton, Gossypium hi... more The cotton fleahopper, Pseudatomocelis seriatus (Reuter), is a major pest of cotton, Gossypium hirsutum L., in Texas and Oklahoma. Although commonly studied as a cotton pest, little is known of the insect parasitoids attacking cotton fleahopper nymphs and adults. We surveyed parasitoids of cotton fleahopper collected during 2 years from wild plant hosts in 17 Texas counties from the Rio Grande Valley to northcentral Texas. The only parasitoid found was Leiophron uniformis (Gahan) (Braconidae). Parasitoids were recovered from 2-4% of nymphs and 0-1% of adults as determined by dissection or by holding cotton fleahoppers for parasitoid emergence. The parasitoid was reared from cotton fleahopper collected from Monarda spp., Solanum elaeagnifolium A. Cavanilles, and Croton glandulosus L., but was not recovered from cotton fleahopper collected on Croton capitatus A. Michaux or Tidestromia lanuginosa (Nutt.) Standl. The low parasitism rate suggested that importation and establishment of parasitoids might be beneficial if increased parasitism resulted in fewer cotton fleahopper adults dispersing from wild hosts into cotton.
Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from ... more Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from 2003 to 2010 for biological control of tamarisk (Tamarix spp.): Mediterranean tamarisk beetles, D. elongata (Brullé) from Greece, also established in New Mexico; subtropical tamarisk beetles, D. sublineata (Lucas) from Tunisia; and larger tamarisk beetles, D. carinata (Faldermann) from Uzbekistan. More than one million tamarisk beetles were released at 99 sites. Species establishment success ranged from 52 to 83%. All three species now co-occur in New Mexico with the northern tamarisk beetles, D. carinulata (Desbrochers). A phenotypic hybrid scoring system was developed to assess Diorhabda phenotype distributions and character mixing in hybrid zones. Widespread field populations of bispecific hybrid phenotypes for D. carinata/D. elongata and D. sublineata/D. elongata rapidly appeared following contact of parental species. Initial distributions and dispersal of Diorhabda spp. and hybrids ...
The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first repo... more The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern United States. Injury results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Injury slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas. Yield loss was estimated to be 9.97 kg/ha (8.90 lbs /acre) for each percentage of stems with bermudagrass stem maggot damage. This relationship was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy, and digestibility of bermudagrass hay was also investigated. A...
Abstract. Four species of leaf beetles, Diorhabda spp, (Chrysomelidae), were introduced for biolo... more Abstract. Four species of leaf beetles, Diorhabda spp, (Chrysomelidae), were introduced for biological control of saltcedar, Tamarix spp., an invasive small tree or shrub, in the US. In Texas, three species established at some sites but failed to establish or initially established but did not persist at other sites. Diorhabda larvae pupate in leaf litter on the soil surface and thus are exposed to ants and other soil-active predators. Predation by ants on Diorhabda pupa was evaluated as a potential factor in limiting establishment of Diorhabda populations at field sites in West Texas. Nighttime observations of pupae found that native ants represented 46-65% and pill bugs (Isopoda: Armadillidiidae) represented 8-51% of observed predation events. The predation rate of Diorhabda pupae by ants was significantly greater where red imported fire ant, Solenopsis invicta Buren, was present. When present, S. invicta was responsible for 93-100% of observed predation during the day. In the absence of S. invicta, native ants Monomorium spp., Crematogaster spp., and Formica perpilosa Wheeler were observed preying on Diorhabda pupae. Results suggested that predation by ants, especially red imported fire ant, could limit establishment of Diorhabda spp. released for biological control of saltcedar.
Abstract. Stink bugs have become important pests of cotton, Gossypium hirsutum L., in the Lower G... more Abstract. Stink bugs have become important pests of cotton, Gossypium hirsutum L., in the Lower Gulf Coast region of Texas. Common species, damage potential, and insecticide susceptibility of stink bugs were assessed. A survey of stink bugs in commercial cotton fields in six counties in the Lower Gulf Coastal region of Texas during 2004 and 2005 revealed that brown stink bug, Euschistus servus (Say); E. quadrator Rolston; and E. obscurus (Palisot) were the most common species (>95% both years), while southern green stink bug, Nezara viridula (L.); and green stink bug, Acrosternum hilare (Say), were less common. This stink bug complex differs from that reported for other areas of the Cotton Belt. Also, significantly more stink bugs were collected in the northern counties of Calhoun, Refugio, and Victoria than in the southern counties of Kleberg, Nueces, and San Patricio (approximately 7.5 and 4 times more in 2004 and 2005, respectively). The potential of E. servus and E. quadrator to damage cotton bolls was compared by caging individual adults on bolls in the field. Both E. servus and E. quadrator caused significant reductions in yield (seed cotton weight) and fiber quality (length and fineness) of cotton bolls. Feeding by both species caused abscission of 1.8-cm-diameter bolls from the plant. In general, E. servus caused more damage to bolls than did E. quadrator and damaged a wider size-range of bolls. Foliar-applied insecticides were evaluated against E. servus, E. quadrator, and N. viridula in small plots of cotton in the field. Dicrotophos was most effective against all species. Pyrethroids killed all N. viridula, but the number of E. servus and E. quadrator killed varied significantly. Euschistus quadrator was more susceptible than E. servus to organophosphate, pyrethroid, neonicotinoid, and carbamate insecticides.
Diorhabda elongata (Brullé) sensu lato leaf beetles have been released in the United States for t... more Diorhabda elongata (Brullé) sensu lato leaf beetles have been released in the United States for the classical biological control of invasive Tamarix L. species, which are exotic trees that are causing deterioration of riparian ecosystems in western North America. The impact of D. elongata defoliation on Tamarix nonstructural carbohydrates (NCHOs) was measured in both manipulative field cage, and non-manipulative natural experiments. Additionally, spring above-ground growth was measured following beetle defoliation in manipulative field cage experiments in Texas. There was no significant difference in the proportional change in NCHOs between beetle-damaged and undamaged control-treatment trees in the manipulative field cage experiment. However, spring above-ground regrowth was reduced by 35% on trees which experienced beetle defoliation the previous fall. In the natural experiment, root crown tissue was sampled in 2005 and 2006 from stands near Lovelock, Nevada in which trees had experienced 0-4 years of beetle defoliation. In 2005, mean NCHO concentrations were statistically different between tree stands and ranged from 9.0 ± 0.8% (mean ± SE) in trees that had not been defoliated to 3.2 ± 0.4%, 2.1 ± 0.4% and 2.3 ± 0.4% in trees in stands that had been defoliated for 1, 2 and 3 successive years, respectively. In 2006, NCHO concentrations were again statistically different between stands and ranged from 13.6 ± 0.9% in trees that had not been defoliated to 7.6 ± 0.8%, 2.3 ± 0.4%, 1.5 ± 0.3% and 1.7 ± 0.4% in trees in stands that had been defoliated for 1, 2, 3 and 4 years, respectively. These results indicate that D. elongata herbivory reduces nonstructural carbohydrates and inhibits regrowth which may lead to reduced survival and reproduction of Tamarix.
... MARVIN HARRIS, I BILL REE, I JOHN COOPEH,2 JOHN JACKMAN,t JONI YOUNG, I HONAL]) LACEWELL,3 AN... more ... MARVIN HARRIS, I BILL REE, I JOHN COOPEH,2 JOHN JACKMAN,t JONI YOUNG, I HONAL]) LACEWELL,3 AND ALLEN KNUTSON4 ... Spraying in 1977used a hydraulic sprayer (at 1,871-2,807Iiters/ha) and, in subsequent years, a Savage model .500mist blower (at 1,207 ...
The cotton fleahopper, Pseudatomoscelis seriatus Reuter, is a widespread and important insect pes... more The cotton fleahopper, Pseudatomoscelis seriatus Reuter, is a widespread and important insect pest of cotton in Texas and Oklahoma. This plant bug feeds on small floral buds, which results in bud abscission, delayed fruiting, and subsequent crop loss. In central and southeastern Texas, two to four insecticide applications are typically applied for cotton fleahopper management. Primitive race stocks of cotton have been identified as an important source of resistance to a wide range of insect pests, but they have not been evaluated for resistance to cotton fleahopper. The objective of this study was to evaluate selected groups of primitive race stocks of Gossypium hirsutum L. for resistance to cotton fleahopper. Resistance was identified by caging cotton fleahoppers on cotton plants in a no-choice feeding trial and comparing the mean number of damaged squares per plant to a standard susceptible genotype. Four primitive race stocks, TX706, TX188, TX1530, and TX1156, were identified as ...
Sugarcane aphid Melanaphis sacchari Zehntner is a significant economic pest of grain sorghum in t... more Sugarcane aphid Melanaphis sacchari Zehntner is a significant economic pest of grain sorghum in the United States. Effective monitoring and early detection are cornerstones for managing invasive pests. The recently developed binomial sequential sampling plan estimates sugarcane aphid economic thresholds (ETs) based on classification whether a 2-leaf sample unit has ≤ or ≥ 50 M. sacchari. In this study, we evaluated eight 2-leaf sampling units for potential use in the sequential sampling plan. From 2016 through 2017, whole plant counts of M. sacchari were recorded non-destructively in situ on sorghum plants from 140 fields located in five states. Plant canopies were stratified into three categories. Two leaves from each stratum were used to compare linear relationships between M. sacchari numbers per two-leaf sample unit and total M. sacchari density per plant. Analysis revealed that two randomly selected leaves from the middle stratum accounted more variation for estimating M. sacch...
The cotton fleahopper, Pseudatomocelis seriatus (Reuter), is a major pest of cotton, Gossypium hi... more The cotton fleahopper, Pseudatomocelis seriatus (Reuter), is a major pest of cotton, Gossypium hirsutum L., in Texas and Oklahoma. Although commonly studied as a cotton pest, little is known of the insect parasitoids attacking cotton fleahopper nymphs and adults. We surveyed parasitoids of cotton fleahopper collected during 2 years from wild plant hosts in 17 Texas counties from the Rio Grande Valley to northcentral Texas. The only parasitoid found was Leiophron uniformis (Gahan) (Braconidae). Parasitoids were recovered from 2-4% of nymphs and 0-1% of adults as determined by dissection or by holding cotton fleahoppers for parasitoid emergence. The parasitoid was reared from cotton fleahopper collected from Monarda spp., Solanum elaeagnifolium A. Cavanilles, and Croton glandulosus L., but was not recovered from cotton fleahopper collected on Croton capitatus A. Michaux or Tidestromia lanuginosa (Nutt.) Standl. The low parasitism rate suggested that importation and establishment of parasitoids might be beneficial if increased parasitism resulted in fewer cotton fleahopper adults dispersing from wild hosts into cotton.
Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from ... more Three Diorhabda spp. tamarisk beetles (Coleoptera: Chrysomelidae) were established in Texas from 2003 to 2010 for biological control of tamarisk (Tamarix spp.): Mediterranean tamarisk beetles, D. elongata (Brullé) from Greece, also established in New Mexico; subtropical tamarisk beetles, D. sublineata (Lucas) from Tunisia; and larger tamarisk beetles, D. carinata (Faldermann) from Uzbekistan. More than one million tamarisk beetles were released at 99 sites. Species establishment success ranged from 52 to 83%. All three species now co-occur in New Mexico with the northern tamarisk beetles, D. carinulata (Desbrochers). A phenotypic hybrid scoring system was developed to assess Diorhabda phenotype distributions and character mixing in hybrid zones. Widespread field populations of bispecific hybrid phenotypes for D. carinata/D. elongata and D. sublineata/D. elongata rapidly appeared following contact of parental species. Initial distributions and dispersal of Diorhabda spp. and hybrids ...
The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first repo... more The bermudagrass stem maggot, Atherigona reversura Villeneuve (Diptera: Muscidae), was first reported damaging bermudagrass Cynodon dactylon (L.) Pers grown for forage in 2010 in the southeastern United States. Injury results from individual larvae feeding internally on the vascular tissue just above the terminal node of the grass stem. Injury slows plant growth and reduces forage accumulation. To address the need for economic guidelines to manage this new pest, the relationship between the percent of stems damaged by bermudagrass stem maggot and forage yield was measured in commercial bermudagrass hay fields in northcentral Texas. Yield loss was estimated to be 9.97 kg/ha (8.90 lbs /acre) for each percentage of stems with bermudagrass stem maggot damage. This relationship was used to calculate economic injury levels for a range of hay market values and control costs. The impact of stem damage on protein content, energy, and digestibility of bermudagrass hay was also investigated. A...
Abstract. Four species of leaf beetles, Diorhabda spp, (Chrysomelidae), were introduced for biolo... more Abstract. Four species of leaf beetles, Diorhabda spp, (Chrysomelidae), were introduced for biological control of saltcedar, Tamarix spp., an invasive small tree or shrub, in the US. In Texas, three species established at some sites but failed to establish or initially established but did not persist at other sites. Diorhabda larvae pupate in leaf litter on the soil surface and thus are exposed to ants and other soil-active predators. Predation by ants on Diorhabda pupa was evaluated as a potential factor in limiting establishment of Diorhabda populations at field sites in West Texas. Nighttime observations of pupae found that native ants represented 46-65% and pill bugs (Isopoda: Armadillidiidae) represented 8-51% of observed predation events. The predation rate of Diorhabda pupae by ants was significantly greater where red imported fire ant, Solenopsis invicta Buren, was present. When present, S. invicta was responsible for 93-100% of observed predation during the day. In the absence of S. invicta, native ants Monomorium spp., Crematogaster spp., and Formica perpilosa Wheeler were observed preying on Diorhabda pupae. Results suggested that predation by ants, especially red imported fire ant, could limit establishment of Diorhabda spp. released for biological control of saltcedar.
Abstract. Stink bugs have become important pests of cotton, Gossypium hirsutum L., in the Lower G... more Abstract. Stink bugs have become important pests of cotton, Gossypium hirsutum L., in the Lower Gulf Coast region of Texas. Common species, damage potential, and insecticide susceptibility of stink bugs were assessed. A survey of stink bugs in commercial cotton fields in six counties in the Lower Gulf Coastal region of Texas during 2004 and 2005 revealed that brown stink bug, Euschistus servus (Say); E. quadrator Rolston; and E. obscurus (Palisot) were the most common species (>95% both years), while southern green stink bug, Nezara viridula (L.); and green stink bug, Acrosternum hilare (Say), were less common. This stink bug complex differs from that reported for other areas of the Cotton Belt. Also, significantly more stink bugs were collected in the northern counties of Calhoun, Refugio, and Victoria than in the southern counties of Kleberg, Nueces, and San Patricio (approximately 7.5 and 4 times more in 2004 and 2005, respectively). The potential of E. servus and E. quadrator to damage cotton bolls was compared by caging individual adults on bolls in the field. Both E. servus and E. quadrator caused significant reductions in yield (seed cotton weight) and fiber quality (length and fineness) of cotton bolls. Feeding by both species caused abscission of 1.8-cm-diameter bolls from the plant. In general, E. servus caused more damage to bolls than did E. quadrator and damaged a wider size-range of bolls. Foliar-applied insecticides were evaluated against E. servus, E. quadrator, and N. viridula in small plots of cotton in the field. Dicrotophos was most effective against all species. Pyrethroids killed all N. viridula, but the number of E. servus and E. quadrator killed varied significantly. Euschistus quadrator was more susceptible than E. servus to organophosphate, pyrethroid, neonicotinoid, and carbamate insecticides.
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