Conophthorus Coniperda Research Articles

Response of Pityophthorus puberulus (Coleoptera: Curculionidae: Scolytinae) to pheromones and terpenes

AbstractIn field studies conducted to improve trapping programs for the white pine cone beetle, Conophthorus coniperda (Schwarz), a twig beetle, Pityophthorus puberulus (LeConte), a common associate of eastern white pine, Pinus strobus L. (Pinaceae), in seed orchards, was also captured. In these experiments, P. puberulus was attracted to traps containing the sex pheromone pityol with or without the monoterpenes (−)-α-pinene and (−)-β-pinene, but attraction to traps was inhibited when S-(−)-limonene was present. We speculate that limonene may play an important role in host recognition and suitability, by indicating a resource suitable for C. coniperda but unsuitable for P. puberulus.

Limonene: Attractant Kairomone for White Pine Cone Beetles (Coleoptera: Scolytidae) in an Eastern White Pine Seed Orchard in Western North Carolina

I report on the attraction of the white pine cone beetle, Conophthoru.s coniperda (Schwarz) (Coleoptera: Scolytidae), to traps baited with the host monoterpene limonene in western North Carolina. Both (+)- and (-)-limonene attracted male and female cone beetles to Japanese beetle traps in an eastern white pine, Pinus strobus L., seed orchard near Murphy, NC. Catches of cone beetles were directly proportional to the release rate of (-)-limonene; (+)-limonene was not tested for dose response. Attraction of cone beetles to the pheromone (+/-)-trans-pityol was increased significantly by both enantiomers of limonene. In all experiments, catches of C. coniperda were strongly male biased with no treatment effect on sex ratio. (- )-Limonene had no effect on trap catches of the predator Enoclerus nigripes (Say) to pityol, whereas (+)-limonene interrupted the attraction of E. nigripes to traps baited with pityol. Of six monoterpenes commonly found in white pine cones, only (-)-alpha-pinene elicited attraction of E. nigripes to Japanese beetle traps.

Field evaluation of host kairomones and pheromones for capture of Conophthorus coniperda (Coleoptera: Scolytidae)

AbstractField studies were conducted to determine the attractiveness of monoterpenes and pheromones to the white pine cone beetle, Conophthorus coniperda (Schwarz), the most destructive cone and seed pest of eastern white pine, Pinus strobus L. (Pinaceae). Limonene was identified as a new attractant that acts synergistically when added to the female-produced sex pheromone, pityol. Trap catches were higher with increasing release rates of S-(–)-limonene. The enantiomers of limonene showed equivalent efficacy on mean trap catch. (–)-β-Pinene was not attractive and may be repellent to both sexes, and (–)-α-pinene was shown to have no effect on female response when added to pityol or pityol + S-(–)-limonene. The pheromones trans-verbenol, trans-pinocarveol, and myrtenol were not attractive to C. coniperda.

Use of pityol to reduce damage by the white pine cone beetle, Conophthorus coniperda (Col., Scolytidae) in seed orchards

Abstract: The white pine cone beetle, Conophthorus coniperda (Schwarz), is a common and destructive pest of eastern white pine cones. The potential of mating disruption as a pest management tool against C. coniperda was tested during this experiment. The 5.5 ha white pine seed orchard used in this study was separated in three equal sections and different blocks were treated with pityol over 2‐year experiments. Ten and 20 pityol dispensers (bubble caps) were hung per treated block in 2001 (east block) and 2002 (centre block), respectively, to evaluate their impact on cone protection. During both seasons, the percentage of damaged cones at permanent stations was evaluated at monthly intervals in the middle of the treated block and at different places in the control area. For both years, the mean reduction in cone damage was 63.7% in the pheromone‐treated blocks. With this study, we have been able to demonstrate that mating disruption could be used as a biological pest management tool for the control of C. coniperda in white pine seed orchards.

Dose and enantiospecific responses of white pine cone beetles, Conophthorus coniperda, to alpha-Pinene in an eastern white pine seed orchard.

The white pine cone beetle, Conophthorus coniperda, exhibited dose and enantiospecific responses to alpha-pinene in stands of mature eastern white pine, Pinus strobus, in a seed orchard near Murphy, North Carolina, USA. (-)-alpha-Pinene significantly increased catches of cone beetles to traps baited with (+/-)-trans-pityol. (+)-alpha-Pinene did not increase catches of beetles to pityol-baited traps and interrupted the response of beetles to traps baited with (+/-)-trans-pityol and (-)-alpha-pinene. Maximal attraction of cone beetles to pityol-baited traps was obtained with lures releasing (-)-alpha-pinene at a rate of 103 mg/day at 23 degrees C. Lures releasing (-)-alpha-pinene at rates lower or higher than 103 mg/day resulted in reduced catches to traps baited with (+/-)-trans-pityol. The sex ratio in all catches was heavily male biased. Attraction of the clerid predator, Thanasimus dubius, to traps baited with (+/-)-trans-pityol increased significantly with the presence of alpha-pinene, irrespective of enantiomeric composition. Maximal attraction of T. dubius to pityol-baited traps occurred with devices releasing (-)-alpha-pinene at the highest rate tested, 579 mg/d at 23 degrees C, a sub optimal rate for cone beetles.

RESPONSE OF CONE AND TWIG BEETLES (COLEOPTERA: SCOLYTIDAE) AND A PREDATOR (COLEOPTERA: CLERIDAE) TO PITYOL, CONOPHTHORIN, AND VERBENONE

AbstractField studies were conducted in the United States and Canada to determine the response of the white pine cone beetle, Conophthorus coniperda (Schwarz), and the red pine cone beetle, Conophthorus resinosae Hopkins, to two potential inhibitors, conophthorin and verbenone, of pheromone communication. Trap catches of male C. coniperda and C. resinosae were significantly reduced and generally declined with increasing concentrations of conophthorin in traps baited with the pityol, a female-produced pheromone. Verbenone did not significantly reduce trap catches of C. coniperda. Conophthorin, but not verbenone, significantly reduced cone attacks by C. coniperda when placed near cone clusters. The twig beetles, Pityophthorus cariniceps LeConte and Pityophthorus puberulus (LeConte), responded to traps with pityol and α-pinene baits alone or with conophthorin. Thanasimus dubius (F) (Coleoptera: Cleridae) was attracted to the pityol and α-pinene, but conophthorin had no effect on attraction of this generalist bark beetle predator. Verbenone significantly reduced trap catches of T. dubius in pityol-baited traps.

RESPONSES OF CONOPHTHORUS SPP. (COLEOPTERA: SCOLYTIDAE) TO BEHAVIORAL CHEMICALS IN FIELD TRIALS: A TRANSCONTINENTAL PERSPECTIVE

AbstractWe tested six behavioral chemicals, pityol, conophthorin, 4-allylanisole, verbenone, 2-hexenol, and α-pinene, in a series of field trials directed at six combinations of Conophthorus Hopkins – Pinus L. spp. (Pinaceae) in sites distributed across North America. Beetle – host tree combinations included Conophthorus ponderosae Hopkins on Pinus ponderosa Laws., C. ponderosae on Pinus monticola Dougl., Conophthorus conicolens Wood on Pinus pseudostrobus Lindl., Conophthorus teocotum Wood on Pinus teocote Schl. & Cham., Conophthorus coniperda (Schwarz) on Pinus strobus L., and Conophthorus resinosae Hopkins on Pinus resinosa Ait. trans-Verbenol was tested only on C. resinosae on P. resinosa. Traps baited with pityol caught more beetles than unbaited traps in nearly all of the assays, and conophthorin consistently inhibited male beetle response to pityol for all species tested. Behavioral responses of species of Conophthorus to α-pinene appeared to parallel host phylogeny, inasmuch as beetles using Haploxylon pines as hosts utilized α-pinene as a synergist for the beetle-produced pityol, whereas beetles using Diploxylon pines as hosts did not. α-Pinene was a synergist for pityol in C. ponderosae on P. monticola and C. coniperda on P. strobus, but not for species of Conophthorus on any other pines tested. Conophthorus ponderosae on P. ponderosa was the only beetle–host combination tested where verbenone was a synergist for pityol, but this effect was not consistent in all years of testing. It was also the only beetle–host combination in which 4-allylanisole was a repellent. For all other beetle–host combinations, verbenone was neutral to slightly repellent and 4-allylanisole was either synergistic or neutral in pityol-baited traps. Promising synergists and interruptants/repellents were identified for implementation in pest-management regimes, including conophthorin as an interruptant for all species of Conophthorus tested, 4-allylanisole as an interruptant for C. ponderosae on P. ponderosa, α-pinene as a synergist for pityol in all species tested on Haploxylon pines, and 4-allylanisole as a synergist for pityol in C. conicolens and C. coniperda.

SEX PHEROMONE OF CONOPHTHORUS PONDEROSAE (COLEOPTERA: SCOLYTIDAE) IN A COASTAL STAND OF WESTERN WHITE PINE (PINACEAE)

An isolated stand of western white pine, Pinus monticola Dougl. ex D. Don, on Texada Island (49°40′N, 124°10′W), British Columbia, is extremely valuable as a seed-production area for progeny resistant to white pine blister rust, Cronartium ribicola J.C. Fisch. (Cronartiaceae). During the past 5 years, cone beetles, Conophthorus ponderosae Hopkins (= C. monticolae), have severely limited crops of western white pine seed from the stand. Standard management options for cone beetles in seed orchards are not possible on Texada Island. A control program in wild stands such as the one on Texada Island requires alternate tactics such as a semiochemical-based trapping program. Females of the related species, Conophthorus coniperda (Schwarz) and Conophthorus resinosae Hopkins, produce (+)-pityol, (2R,5S)-2-(1-hydroxyl-l-methylethyl)-5-methyl-tetrahydrofurana, sex pheromone that attracts males of both species (Birgersson et al. 1995; Pierce et al. 1995). The host compound a-pinene significantly increases attraction of male C. coniperda to pityol-baited traps in stands of eastern white pine, Pinus strobus L. (de Groot et al. 1998).

Field Bioassays of Synthetic Pheromones and Host Monoterpenes for Conophthorus coniperda (Coleoptera: Scolytidae)

Four major monoterpenes, (±)- α -pinene, l( S )-(–)- β -pinene, ( R )-(+)-limonene, and myrcene are found in the cones of eastern white pines, Pinus strobus L. Mixtures of these, as well as, α -pinene or β -pinene alone, increased catches of male white pine cone beetles, Conophthorus coniperda (Schwartz), in traps baited with the female sex pheromone, (±)- trans -pityol. The monoterpenes by themselves as mixtures or individually ( α -pinene, β -pinene) were not attractants for males or females. Traps baited with (±)- trans -pityol and α -pinene caught as many, or significantly more beetles than those baited with pityol and a four monoterpene mixture (1:1:1:1) used in seed orchards in North Carolina, Ohio, and Virginia. Three beetle-produced compounds, conophthorin, trans-pinocarveol, and myrtenol did not enhance catches of males or females in (±)- trans -pityol-baited traps. Racemic E -(±)- conophthorin, E -(−)- conophthorin, and E -(+)- conophthorin significantly reduced catches of males in traps baited with (±)- trans -pityol alone. Female C. coniperda were not attracted to any of the host- or beetle-produced compounds tested. The study demonstrated that traps with baits releasing (±)- trans -pityol at about 1mg/wk with (±)- α -pinene (98% pure) are potentially valuable tools for C. coniperda pest management. Baited traps can be used to monitor C. coniperda populations or possibly to reduce seed losses in a beetle trap-out control strategy.

Factors affecting capture of the white pine cone beetle, Conophthorus coniperda (Schwarz) (Col., Scolytidae) in pheromone traps

Abstract: The white pine cone beetle, Conophthorus coniperda, is a serious pest of seed orchards. The sex pheromone (+)‐trans‐pityol, (2R,5S)‐2‐(1‐hydroxy‐1‐methylethyl)‐5‐methyltetrahydrofuran, shows considerable promise to manage the cone beetle populations in seed orchards. Our work confirms that pityol is an effective attractant to capture male C. coniperda. Traps need to be placed in the tree crown, preferably in the cone‐bearing region, to trap out more insects. Japanese beetle traps were superior to the Lindgren funnel traps in capturing insects and trap colour had no significant effect. Commercially available bubble caps for dispensing pheromone were as effective as the experimental ‘vial and wick’ and the glass capillary tube units. Pityol released at about 0.1 mg ṁ day−1 (100 female equivalents) was effective, and higher (more expensive) rates did not significantly improve trap catch.

Pheromones in white pine cone beetle,Conophthorus coniperda (schwarz) (Coleoptera: Scolytidae)

Female white pine cone beetles,Conophthorus coniperda, attacking second-year cones of eastern white pine,Pinus strobus L., produced a sex-specific pheromone that attracted conspecific males in laboratory bioassays and to field traps. Beetle response was enhanced by host monoterpenes. The female-produced compound was identified in volatiles collected on Porapak Q and in hindgut extracts as (+)-trans-pityol, (2R,5S)-(+)-2-(1-hydroxy-1-methylethyl)-5-methyltetrahydrofuran. Males and females produced and released the (E)-(-)-spiroacetal, (5S,7S)-(-)-7-methyl-1,6-dioxaspiro[4.5]decane, which was not an attractant for either sex, but acted as a repellent for males. Porapak Q-trapped volatiles from both sexes contained (+)-trans-pinocarveol and (-)-myrtenol. In addition, hindgut extracts of females containedtrans-verbenol, while males had pinocarvone and verbenone. Work in Georgia and Canada confirmed that the same isomers of pityol and spiroacetal are present in two distinct and widely separated populations ofC. coniperda.

EVIDENCE FOR A FEMALE-PRODUCED PHEROMONE IN THE WHITE PINE CONE BEETLE, CONOPHTHORUS CONIPERDA (SCHWARZ), AND IN THE RED PINE CONE BEETLE, C. RESINOSAE HOPKINS (COLEOPTERA: SCOLYTIDAE)

AbstractEvidence for a female-produced sex pheromone in the white pine cone beetle, Conophthorus coniperda (Schwarz), and the red pine cone beetle, C. resinosae Hopkins, was obtained from laboratory bioassays and field experiments conducted with C. coniperda beetles from Ontario and North Carolina. In an olfactometer, males from both species responded significantly more to volatiles from females than to volatiles from males or cones. Generally, females did not differ in their response to female-, male-, or cone-produced volatiles. Both sexes responded to host volatiles. The strong response by male C. coniperda to females was confirmed in field tests.

Control of White Pine Cone Beetle (Coleoptera: Scolytidae) with Carbofuran Granules in a New York State White Pine Seed Orchard

An eastern white pine ( Pinus strobus L.) seed orchard was used to test the effects of carbofuran on the white pine cone beetle, Conophthorus coniperda (Schwarz). A total of 120 cone-bearing trees was used in the study. Carbofuran was applied to the soil around the drip line of 60 trees in April 1985 at a rate of 55.8 g/cm of diameter at breast height. Thirty of the treated trees received a second application at the same rate in October 1985. The single April application of carbofuran was applied too late in the season to control the white pine cone beetle in the seed orchard effectively. However, significant control was obtained in 1986 for trees that received carbofuran applications in both April and October 1985.

CYTOTAXONOMY OF CONOPHTHORUS (COLEOPTERA: SCOLYTIDAE) IN EASTERN NORTH AMERICA

AbstractThe male meiotic karyotypic formula of Conophthorus coniperda (Schwarz) (Coleoptera: Scolytidae) is 9AA + XY. This karyotype differs from C. resinosae Hopkins and C. banksianae McPherson, both of which have the karyotypic formula of 8AA + XY. Supernumerary chromosomes were found in different populations of C. resinosae and C. banksianae but were absent in C. coniperda. No geographic variation in the karyotypes of the three species was observed. The karyotypic formulae confirm the designations of C. coniperda and C. resinosae by morphological characters, but do not support the designation of C. banksianae as a distinct species.

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.

Behavior and Generation Dynamics of the White Pine Cone Beetle Conophthorus coniperda (Schwarz) in Central Wisconsin1

Estimates from 2 weekly analyses of its population density indicate there are relatively small decreases in populations of Conophthorus coniperda during the immature stadia. Sharp declines in density occur in the adult stage, nearly 50% of the insects disappearing from the habitat in autumn and more than 20% drowning in waterlogged cones as snow melts in spring. Hibernation is a temperature-controlled quiescence; insects quickly become active, fly, attack and oviposit in new host tissue, once returned to suitable temperatures. Adults have a relatively consistent sequential series of behavior patterns associated with dispersal, reproduction, and autolysis and regeneration of vertical thoracic wing muscles. They appear to prefer different host-tissue conditions for oviposition and for feeding. Controls for this beetle are briefly discussed, in terms of recommendations in the literature and our studies of both its biology and relationship with the food-plant.

The Life History of the White-Pine Cone Beetle, Conophthorus coniperda

The life history of the white-pine cone beetle, Conophthorus coniperda (Schwarz), was studied in the vicinity of New Haven, Connecticut, in 1958-60. The various life stages and seasonal development are described. The adult female leaves its hibernation place in the litter in April, flies to a developing white-pine cone, and bores into the cone at its junction with the petiole and quickly kills it by girdling. A gallery is bored down the axis of the cone and eggs are deposited in niches along its length. There are 2 larval instars. New adults are present in July. Most adults stay within the infested cones, on the ground, until the following spring.

Laboratory Studies on the Adult Behavior of Conophthorus coniperda(Coleoptera: Scolytidae). III. Flight

Adults of the white-pine cone beetle, Conophthorus coniperda (Schwarz), undertook spontaneous flight most frequently at temperatures between 27.5° and 35° C, Flight frequency was increased by exposure to dry air, although prolonged exposure resulted in water loss and cessation of flight. Preliminary exposure to light also increased flight frequency. On flight mills, beetles flew continuously for periods up to 5 hours, but the great majority of tethered flights were of only a few minutes' duration. In free flight the insects oriented to a point source of light; with diffuse light they were still photopositive, and tended to fly a horizontal course and to orient to dark silhouettes. These mechanisms would result in the movement of the beetles from their overwintering sites to the cone-bearing terminals of the trees. The mean duration of flight in the field is probably rather short, because the beetles would fly just above the mean crown surface and would orient to the dark silhouettes of the dominant leaders.

Laboratory Studies on the Adult Behavior of Conopthorus coniperda (Schwarz) (Coleoptera: Scolytidae). II. Thigmotropic Aggregation

The white pine cone beetle ( Conophthorus coniperda (Schwarz)) ionns aggregations when confined in open arenas in the laboratory. These aggregations are stable and immobile. They appear to be symptomatic of a strong thigmotropism which leads the insect to increase its body contact. The extent of aggregation is increased by a variety of physical conditions which tend to increase overall activity and thus provide more opportunities for collisions. The seasonal change in the reaction makes it a useful model for the investigation of aggregation in general, as well as providing additional understanding of the field behavior of the insect.

Laboratory Studies on the Adult Behavior of Conophthorus coniperda (Schwarz) (Coleoptera: Scolytidae). I. Seasonal Changes in the Internal Anatomy of the Adult

Conophthorus coniperda does not feed from the time of adult emergence to the following spring. The gonads develop only after feeding, mating takes place at least twice, and oviposition continues over a considerable period. Flight muscle degeneration takes place at the time of gonadal activity. Regeneration is apparently possible, at least in some individuals. Starvation of adults at definite periods of the year suggests the severity of competition for suitable food within even a moderate population.