Leptoglossus Corculus Research Articles

Biochemical Assay Detects Feeding Damage to Loblolly Pine Seeds Caused by the Leaffooted Pine Seed Bug (Hemiptera: Coreidae)

A large number of proteins in salivary gland extracts of the leaffooted pine seed bug, Leptoglossus corculus Say, were strongly recognized by a polyclonal antibody-based assay developed for detecting saliva of the western conifer seed bug. Leptoglossus occidentalis Heidemann, in lodgepole pine, Pinus contorta var. latifolia Engelmann, seeds. An average of approximately 85% of loblolly pine, Pinus taeda L., seeds exposed to feeding by L. corculus for 1 to 4 weeks in the laboratory contained detectable amounts of salivary proteins when the antibody assays were performed weekly on samples (n = 10) of seed. In comparison, radiography of exposed seed detected an average of approximately 63% damaged seed over the same 4-wk period, indicating that the antibody assay increased sensitivity of damage detection by approximately one-third. Depletion of insoluble polypeptides and proliferation of soluble polypeptides ≤23.5 kDa was apparent after SDS-PAGE and quantitative assays were performed on proteins extracted from seeds that were damaged by exposure to L. corculus feeding. Our data suggest that the antibody-based test could be used to obtain accurate estimates of seed losses attributable to L. corculus feeding in southern pine seed orchards.

PERSISTENCE OF INSECTICIDES IN A LOBLOLLY PINE SEED ORCHARD FOR CONTROL OF THE LEAFFOOTED PINE SEED BUG, LEPTOGLOSSUS CORCULUS (SAY) (HEMIPTERA: COREIDAE)

AbstractHigh volume sprays of azinphosmethyl, chlorpyrifos, fenvalerate, permethrin, and phosmet in various concentrations and formulations were simulated on loblolly pine (Pinus taeda L.) foliage in a pine seed orchard in northern Georgia. Persistence of these insecticides under field conditions was determined by weekly bioassays with adult leaffooted pine seed bugs [Leptoglossus corculus (Say)] and gas–liquid chromatography. Fenvalerate was the most persistent insecticide tested. In the first experiment, 0.2% AI fenvalerate caused virtually 100% seed bug mortality in bioassays through the 4th week after treatment, whereas mortality from azinphosmethyl dropped to ca. 14%. By the 6th week, mortality in the fenvalerate treatment was still 91%, even after 10.5 cm of rain. The permethrin treatments persisted for 2 weeks, then mortality declined below 40% at 3 weeks. In the second experiment, fenvalerate at 0.15% AI and 0.075% AI caused 95 and 90% mortality, respectively, after 3 weeks and 16 cm of rain, and the toxicity of the 0.038% and the 0.019% AI fenvalerate treatments lasted only 2 weeks with 12 cm rain. Permethrin in Ambush® EC at 0.2% AI had initial residues of about 150 ppm and caused ca. 84% mortality for 2 weeks with 12 cm rain. Azinphosmethyl WP at 0.2% AI had initial residues of ca. 104 ppm and persisted for 1 week. Seed bug mortality from phosmet at 0.4% AI diminished quickly after 1 week in the field.

Evaluation of Aerial Applications of Acephate and Other Insecticides for Control of Cone and Seed Insects in Southern Pine Seed Orchards2

Acephate was evaluated for control of cone and seed insects in southern pine seed orchards from 1980 to 1985. Insecticides compared with acephate during this study were azinphosmethyl, fenvalerate, malathion, and the bacterium Bacillus thuringiensis. Insecticides were applied aerially, by hydraulic sprayers, and by airblast sprayers. Experiments were conducted in loblolly pine seed orchards in Florida and North Carolina and in two slash pine seed orchards in Florida. Control of coneworms, Dioryctria spp., slash pine flower thrips, Gnophothrips fuscus (Morgan), and two seed bugs, the leaffooted pine seed bug, Leptoglossus corculus (Say), and the shieldbacked pine seed bug, Tetyra bipunctata (Herrich-Schäffer) was evaluated. Frost damage and a serious infection of southern cone rust, Cronartium strobilinum (Arth.) Hedgc, and Hahn, caused significant flower and conelet losses and may have obscured differences between treatment effects during some years. All of the insecticide treatments were equally effective in controlling coneworms. The percentages of trees infested with pine tortoise scale, Toumeyella parvicornis (Cockerell), and the striped pine scale, T. pini (King), and the numbers of scale insects per branch after five applications of insecticide, differed significantly for acephate and fenvalerate treatments.

Rainfastness of Insecticide Deposits on Loblolly Pine Foliage and the Efficacy of Adjuvants in Preventing Washoff

The rainfastness of several insecticides on loblolly pine foliage was determined by using a laboratory rain chamber and by testing the foliage in bioassays with adult leaffooted pine seed bugs, Leptoglossus corculus (Say). The efficacy of eight commercial and two experimental adjuvants in preventing rainwashing of deposits of azinphosmethyl and phosmet from loblolly pine foliage was also determined. Deposits of azinphosmethyl from 0.2% (Al) simulated sprays made from emulsifiable concentrates (EC's), (Guthion 2S and 2L), were highly susceptible to rainwashing. Regression analysis of these data showed a significant linear relationship between arcsin percent mortality and rainfall amount in cm [y = 68.08 – 6.88/(Rainfall)]. Using the confidence intervals from the regression analysis, it was estimated that rainfall in excess of 1.42 cm would reduce mean seed bug mortality on treated foliage to an amount below 80% with 95% confidence, and likewise, rainfall in excess of 3.95 cm would reduce mean mortality to an amount below 50%. However, mortality of L. corculus on deposits of simulated azinphosmethyl 0.2% (Al) sprays made from the wettable powder (Guthion 50 WP) were virtually unaffected by 15 cm of rain. Spray deposits from permethrin (Pounce 3.2EC) at lower rates were moderately to highly resistant to rainwashing. Regression analyses perfomed on these data showed no significant relationship between mortality and rainfall amount. Most of the adjuvants were ineffective in preventing rainwashing of deposits of azinphosmethyl (EC) or phosmet (WP). Only two, Bio-Film and Exhalt 800, showed any promise.

Toxicities of Insecticide Residues on Loblolly Pine Foliage to Leaffooted Pine Seed Bug Adults (Heteroptera: Coreidae)2

Fourteen commercial and four experimental formulations of insecticides, when applied to loblolly pine, Pinus taeda L., foliage in a simulated high volume spray, varied in their residual contact toxicities to adult leaffooted pine seed bugs, Leptoglossus corculus (Say). Deltamethrin emulsifiable concentrate (EC), the most toxic insecticide tested, was 7 times as toxic to adult females as the standard, azinphosmethyl EC. Azinphosmethyl wettable powder (WP) was slightly more toxic to females than the EC at LC90; all other insecticides were less toxic than azinphosmethyl EC to females (half or less). Azinphosmethyl EC, deltamethrin EC, permethrin (Pounce) EC, and phosmet WP were equally toxic to both sexes, while permethrin (Ambush) EC and fenvalerate EC were both more toxic to males than females. Azinphosmethyl WP was more toxic to females than males. Several of the insecticides, including propoxur WP, malathion EC and chlorpyrifos EC, had relatively low residual contact toxicities but were very toxic to seed bug adults as fumigants. The pyrethroids permethrin, deltamethrin and fenvalerate had a relatively rapid knockdown effect, in contrast to the slower-acting organophosphorous insecticides.

Low-volume Applications of Azinphosmethyl, Fenvalerate, and Permethrin for Control of Coneworms (Lepidoptera: Pyralidae) and Seed Bugs (Hemiptera: Coreidae and Pentatomidae) in Southern Pine Seed Orchards

Mist-blower applications of 0.9% wt/wt (AI) azinphosmethyl or 0.0625, 0.125, and 0.25% fenvalerate and permethrin repeated five or six times at monthly intervals effectively controlled cone worms, Dioryctria spp., in loblolly pine, Pinus taeda L., seed orchards in South Carolina but were less effective in Louisiana. Mist-blower applications of all concentrations of fenvalerate reduced cone worm losses by 52 to 67% in South Carolina. Permethrin at the two lowest concentrations was as effective in South Carolina, but failed to provide control in Louisiana. All three concentrations of permethrin and 0.9% azinphosmethyl, the standard, reduced seed losses caused by the leaf footed pine seed bug, Leptoglossus corculus (Say), and the shield backed pine seed bug, Tetyra bipunctata (Herrich-Schäffer), in Louisiana. Seed bug damage was too low in South Carolina to evaluate efficacy. Aerial application of azinphosmethyl at rates of 2.25 kg (AI)/ha in Louisiana and 3.37 kg (AI)/ha in North Carolina and fenvalerate at 0.75 kg (AI)/ha and 0.84 kg (AI)/ha at these same locations effectively reduced cone worm and seed bug damage. These pilot tests demonstrated that large increases in cone survival and seed yields can be attained in production seed orchards. Cone survival in the North Carolina orchard was 82% on trees aerially sprayed with azinphosmethyl and 86% on trees sprayed with fenvalerate, but only 14% on unsprayed trees. Cones from sprayed trees in this orchard averaged 132 filled seeds per cone compared to only 63 on unsprayed trees.

High-volume Applications of Azinphosmethyl, Fenvalerate, Permethrin, and Phosmet for Control of Coneworms (Lepidoptera: Pyralidae) and Seed Bugs (Hemiptera: Coreidae and Pentatomidae) in Southern Pine Seed Orchards

Mist-blower applications of 0.9% wt/wt (AI) azinphosmethyl or 0.0625, 0.125, and 0.25% fenvalerate and permethrin repeated five or six times at monthly intervals effectively controlled cone worms, Dioryctria spp., in loblolly pine, Pinus taeda L., seed orchards in South Carolina but were less effective in Louisiana. Mist-blower applications of all concentrations of fenvalerate reduced cone worm losses by 52 to 67% in South Carolina. Permethrin at the two lowest concentrations was as effective in South Carolina, but failed to provide control in Louisiana. All three concentrations of permethrin and 0.9% azinphosmethyl, the standard, reduced seed losses caused by the leaf footed pine seed bug, Leptoglossus corculus (Say), and the shield backed pine seed bug, Tetyra bipunctata (Herrich-Schaffer), in Louisiana. Seed bug damage was too low in South Carolina to evaluate efficacy. Aerial application of azinphosmethyl at rates of 2.25 kg (AI)/ha in Louisiana and 3.37 kg (AI)/ha in North Carolina and fenvalerate at 0.75 kg (AI)/ha and 0.84 kg (AI)/ha at these same locations effectively reduced cone worm and seed bug damage. These pilot tests demonstrated that large increases in cone survival and seed yields can be attained in production seed orchards. Cone survival in the North Carolina orchard was 82% on trees aerially sprayed with azinphosmethyl and 86% on trees sprayed with fenvalerate, but only 14% on unsprayed trees. Cones from sprayed trees in this orchard averaged 132 filled seeds per cone compared to only 63 on unsprayed trees.

CONTACT TOXICITIES OF 12 INSECTICIDES TO LEPTOGLOSSUS CORCULUS ADULTS (HEMIPTERA: COREIDAE)

AbstractContact toxicities of 12 insecticides to adult Leptoglossus corculus (Say) were determined. All insecticides tested were moderately to highly toxic to adult females. Five insecticides—decamethrin, carbofuran, aminocarb, fenvalerate, and bioethanomethrin—were as toxic or more toxic than the standard, azinphosmethyl, at LD90. Decamethrin (LD90 =.06 μg/g body wt.) was 29 times more toxic than azinphosmethyl at LD90. Five insecticides—carbofuran, bioethanomethrin, resmethrin, azinphosmethyl, and chlorpyrifos—were tested on males also. The first three were significantly more toxic to females than males and the latter two were equally toxic to both sexes. All but two insecticides, decamethrin and bioethanomethrin, were equally toxic or more toxic to second-stage nymphs than adult females.

Use of carbofuran for control of eastern white pine cone and seed insects

The major insects that destroy cones and seeds of eastern white pine, Pinus strobus L., were controlled with soil applications of the systematic insecticide carbofuran in orchards at Murphy and Morganton, NC, U.S.A. Carbofuran applied once a year at rates of 4.5, 9.0 or 13.5 g AI (active ingredient) per cm of diameter at breast height protected trees from the white pine cone beetle, Conophthorus coniperda (Schwarz), the leaffooted pine seed bug, Leptoglossus corculus (Say), the shieldbacked pine seed bug, Tetyra bipunctata (Herrich-Schäffer), and the white pine cone borer, Eucosma tocullionana Heinrich. Control was reflected by increased cone survival and increased yields of filled seeds per cone. Increasing the rate of application from 4.5 to 9.0 or 13.5 g generally improved control, but the improvement was not of statistical or practical significance. Carbofuran was ineffective against a seed chalcid, Megastigmus atedius (Walker). White pine clones varied in inherent susceptibility to insect attacks.

Color Variation in Nymphs of Leptoglossus corculus

An uncommon, green nymphal form of Leptoglossus corculus (Say) (Hemiptera: Coreidae) was collected, reared, and established as a laboratory colony. Breeding studies indicated that the green color was dominant over the usual brownish color of nymphs of this bug.

Comparison of Damage by Each Life Stage of Leptoglossus corculus and Tetyra bipunctata to Loblolly Pine Seeds123

Studies in 2 Louisiana seed orchards showed the extent of ovule and seed losses in cones of loblolly pine exposed to nymphs and adults of a seed bug Leptoglossus corculus (Say) and the shieldbacked pine seed bug Tetyra bipunctata (Herrich – Shaffer). Seed loss in uncaged cones was 56% compared to 22% in cones protected throughout the season. Damage by T. bipunctata adults in caging tests conducted prior to seedcoat formation was significantly less than that caused by any stage of L. corculus . However, after seedcoat formation, there was no significant difference in total impact of L. corculus or T. bipunctata on cones exposed for 2-week feeding periods. Prior to seedcoat formation, the percentages of full seeds in cones exposed to 3rd–5th instars and adults of L. corculus were similar. After seedcoat formation, however, these percentages differed significantly among stages. The 5th instar caused a significantly greater percentage of empty seeds than occurred in cones exposed to 3rd instars and adults, or in check cones. There was no significant difference in empty seeds in check cones exposed to 3rd–5th instars or adults of T. bipunctata after seedcoat formation. The 5th instar, however, did cause a significantly greater percentage of seedbug-damaged seeds than 3rd and 4th instars or adults.

CONTACT TOXICITY OF 34 INSECTICIDES TO SECOND-STAGE NYMPHS OF LEPTOGLOSSUS CORCULUS (HEMIPTERA: COREIDAE)

AbstractSecond-stage nymphs of the leaffooted pine seedbug, Leptoglossus corculus (Say), were highly susceptible to most of 34 topically applied insecticides, twenty-six chemicals ad Ld50 values of less than 5 μg/g of body weight. Nine insecticides — aldicarb, aminocarb, azinphosmethyl, carbofuran, dicrotophos, FMC 45498 ((−)-(Cyano) (3-phenoxyphenyl)-methyl (+)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylate), monocrotophos, propoxur, and SD 43775 (Cyano(3-phenoxyphenyl)methyl-4-chloro-alpha-(1-methylethyl)benzeneacetate) — had LD90 values of less than 1 μg/g of body weight. There was good agreement between the relative toxicities of insecticides applied topically to the leaffooted pine seedbug in these laboratory tests and the effectiveness of several insecticides previously tested in the field.

Impact of Insect Damage on Loblolly Pine Seed Production

Conelets and cones on sample branches of loblolly pine, Pinus taeda L., in the Georgia Piedmont were monitored for 2 years to determine damage from insects, seasonal pattern of losses, and overall loss of potential seed. Conelet losses were 32% in 1969 and 18% in 1970. Over 70% of this loss was unaccountable abortion or disappearance, which we attribute in part to feeding by a bug, Leptoglossus corculus (Say). For 2nd-year cones, losses were 37% in 1969 and 22% in 1970. A majority of these losses was accountable; they were caused primarily by damage from various Coneworms, Dioryctria spp., in midsummer. Survival from conelet to harvested cone was 51.4% However, harvested cones held only 42.6% of the potential seed, and only 64.8% of the harvested seeds were full; seedbugs contributed to this final stage of loss. Overall, only 14.2% of the potential seed survived to maturity.

ANATOMICAL BASIS FOR CONELET ABORTION ON PINUS ECHINATA FOLLOWING FEEDING BY LEPTOGLOSSUS CORCULUS (HEMIPTERA: COREIDAE)

AbstractSecond-instar nymphs of Leptoglossus corculus (Say) confined to shortleaf pine conelets for only 4 days caused 100% conelet abortion. The bugs fed almost exlusively on the cytoplasm of cells of the nucellar tissue. Feeding in May produced an abscission zone in only a few days and resulted in conelet abscission in less than 2 weeks. Similar ovule destruction, followed by conelet abortion, occurred in late summer after being fed upon by the same instar, but conelet abscission was prevented because of a greater proportion of tracheary elements in the conelet stalks.

Insect-Caused Damage and Mortality to Conelets, Cones, and Seed of Short leaf Pine

The sequence of insect-caused damage and mortality to conelets and 2nd-year cones of shortleaf pine, Pinus echinata Mill, was followed over the 2-year period of cone development in the Georgia Piedmont. During the 1st year, major conelet loss was attributed to infestation by the Nantucket pine tip moth, Rhyacionia frustrana (Comstock), and to abortion, possibly the result of feeding by a seedbug Leptoglossus corculus (Say). Over 70% of the tota1 recorded mortality occurred during this 1st year of cone development. Subsequent disappearance after the initia1 observation accounted for 38% of the conelet loss in 1968 and 62% of the loss of overwintering cones during 1969. Major 2nd-year cone loss was attributed to a combination of coneworms (Dioryctria spp.), a coneborer (Eucosma cocana Kearfott), and midges (Cecidomyiidae). However, loss of nearly half of the seed within the cones, probably the result of seedbug feeding, was the greatest single factor affecting ultimate seed yields of the study trees.

Trunk implantations of dicrotophos for cone-insect control in slash pine seed production stands.

Presented are the results of 4 years of research in north Florida on dicrotophos trunk implantation to control Dioryctria spp. coneworms and the slash pine seedworm, Laspeyresia anaranjada Miller, on 2nd-year cones of slash pine, Pinus elliottii var elliotti Engelm. Dicrotophos technical liquid (1.08 kg active ingredient (AI) per liter) was implanted in early May into holes drilled in the tree stems. Dosage rates of 0.8–2.0 g AI per cm of tree diameter at waist height gave 86–94% control of Dioryctria spp. and 94–100% control of M L. anaranjada on mature cones harvested in mid-September of the year of treatment. Dicrotophos implanted by Mauget® injectors at dosages of 0.6–1.4 g/cm diameter resulted in 30–81% control of Dioryctria spp. and 56–97% control of slash pine seedworm. Date of treatment may be advanced to early April and good control of both insects still be obtained. Foliage of trees implanted with dicrotophos in early May showed no phytotoxic symptoms at the dosages tested. Seeds from trees implanted with a 1.4 g per cm-diameter dosage of dicrotophos for 3 consecutive years showed no decrease in full-seed germination percentage when compared with seeds from untreated trees. Seed losses caused by the hemipteran seed bugs Leptoglossus corculus (Say) and Tetyra bipunctata (Herrich-Schaeffer) were also reduced with dicrotophos implants.

Characteristics and Radiographic Detection of Seed Bug Damage to Slash Pine Seed

A leaf-footed bug, Leptoglossus corculus (Say), and the shield-back bug, Tetyra bipunctata (H. + S.), feed on seeds of the major pine species grown in seed orchards in the Southeast. Characteristics of the inconspicuous damage caused by these seed bugs are described, along with the use of radiography to detect damage in mature seed. At least 82% as many damaged seeds were detected on radiographs as could be detected in ocular examination at 60X.