Trap Trees Research Articles

Relationship Between Fall Catches of Campylomma verbasci (Heteroptera: Miridae) in Traps Baited with Females and Density of Nymphs in the Spring

Male mullein bugs, Campylamma verbasci (Meyer), were captured in 27 traps baited with live females in the fall within 10 apple orchards in the Okanagan Valley, British Columbia. When the catches of males from 14 September to 13 October 1987 were compared with limb tap samples of nymphs in the following spring, the relationships in the trap trees (r2 = 0.61) and trees adjacent to the trap trees (r2 = 0.56) were significant. Similar positive relationships occurred for four shorter trapping intervals but not for the final interval from 3 to 13 October, when trap catches were low. These results suggest that when a synthetic pheromone is available for this mirid, prediction of economic injury levels may be made in the fall, 6-8 mo before egg hatch. Limb tap sampling in the spring could then be concentrated in orchards with the highest probability of damage to the crop.

Opciones de control para Sirex noctilio: una revisión * (Hymenoptera - Siricidae)

Sirex noctilio Fabricius, a woodwasp, represents today a serious potential pest for the main forest resource in Chile: Pinus radiata, D. Don. Specially vulnerable to the pest are the extensive monoespecific plantations in marginal sites, in edaphoclimates zones of high risk and in places where the lack of silvicultural management makes an opening for the establishing of Sirex. This is of special concern since an introduced species without natural enemies rapidly increases its density and dispersion rates. This is a review of the principal control measures adopted by Australia and New Zealand, with more than 50 years of research in Sirex. Two kinds of measures have been used and some of them evaluated: Preventives which consider legal and silvicultural practices, and Curatives, which comprises biological control with parasites andparasitoids or integrated control with trap tree techniques and specific bioregulatoring agents. The Chilean forestry sector is now compiling within the Forest Sanitary Committee (Sub-commission Sirex) all the basic biological and technological knowledges about this pest. This review is a contribution to this objective.

The recent Ips typographus outbreak in Norway ‐ experiences from a control program

During the period 1971‐81 there were severe outbreaks of the bark beetle Ips typographus in southern Norway that damaged trees equivalent to 5 million cubic metres of timber. The outbreaks were caused partly by an extensive windblow and partly by drought. Trap trees were used until 1979, when pheromone‐baited traps were introducted as part of an extensive control program. The various aspects of this program are outlined and problems of scientific, technological, economical‐administrative and informative character are discussed. Possible explanation for the decline of the epidemic after 1980 is presented and the main conditions which must be fulfilled for achieving successful mass trapping of insect pests are listed.

The European struggle to control Ips typographus ‐ past, present and future

The achievement of the Scandinavian campaign is seen in the swift development and unorthodox transfer of an innovative trapping technique into the management of pest populations of the spruce engraver Ips typographus without the use of pesticides. The pheromone traps proved to be far more efficient in the prevention of engraver reproduction and the reduction of beetle numbers than the cumbersome trap trees they replaced. The wholesale application of pheromone traps as an integrated part of engraver pest management is justified alone by the empirically proven benefits that result from a “surveillance with the intent to control”, although appraisal of the actual impact of trapping on the population density remains scientifically ambiguous for the lack of reliable methodology. Furthermore, the campaign opens a new era in bark beetle management by stipulating for the commercial availability of pheromones and traps as well as for research on basic and applied aspects. As the years to come may show, behaviour chemistry is likely to bear more promises to engraver management than just trapping techniques.

Behaviour of female and male Mediterranean fruit flies, Ceratitis capitata in and around Jackson traps placed on fruiting host trees

We studied the distribution of wild Mediterranean fruit flies, Ceratitis capitata (Diptera: Tephritidae) in different environments of trimedlure-baited Jackson traps during high fall season populations in Southern Egypt. We found that 98% of females attracted to within aim radius of standard trimedlure (TML)-baited Jackson traps remained on the surrounding foliage without approaching the trap. Also about 30 % of males aggregated there, calling and competing for matings with approaching females. The closest mating occurred 25 cm from a standard trap. The nearest lek formation away from a trap was observed at a distance of 2 m on the same trap tree. The highest captures of males were recorded in the morning after male calling on the foliage reached its daily peak. Jackson traps baited with both protein hydrolyzate and TML on cotton wicks caught as many males, but significantly more females than traps with TML only.

Trap Trees for Control of Dutch Elm Disease

Diseased or unwanted elms treated with cacodylic acid or monosodium methylarsonate (MSMA) by injection or topical application to axe or chain saw cuts are colonized by elm bark beetles, but herbicide-induced drying of the bark suppresses brood production. Treated trees need not be removed for the sake of Dutch elm disease (DED) control and their wood can be utilized for fuel and other purposes. Experimental and operational applications of this technique have been followed by reduced rates of DED infection. Time required to treat a tree averages about 15 min and per tree cost of materials ranges from a few cents to about $10. A one or two person crew working full time during the growing season can apply the trap tree technique to all diseased trees in a population of about 100,000 elms.

Impact and Role of Monosodium Methanearsonate on Attack and Progeny Production by the Douglas-Fir Beetle (Coleoptera: Scolytidae) in Lethal Trap Trees

Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, trees located in interior British Columbia were baited with frontalin and treated with monosodium methanearsonate (MSMA) on two dates. The first treatment was 2 wk before initial Douglas-fir beetle, Dendroctonus Pseudotsugae Hopkins, flight, and the second coincided with flight. Each application was subjected to three felling regimes (2 and 4 wk, and unfelled) after treatment, as were the controls. MSMA significantly reduced the number of Douglas-fir beetle progeny in all cases but was most effective (greatest attacks, 80% reduction in progeny) in trees treated at the time of initial beetle flight and felled 4 wk later. The unfelled trap trees were least effective (fewest attacks, greatest survival). Samples of phloem and xylem were subjected to arsenic compound (speciation) analysis which identified significant concentrations of inorganic arsenic (arsenate plus arsenite), monomethylarsonic acid (MMAA), and cacodylic acid (DMAA) in treated and untreated trees. The control tree contained mainly inorganic arsenic, but the presence of MMAA and DMAA was consistent with in situ biomethylation. Treatment with MSMA resulted in much higher levels of all arsenicals, with concentrations generally decreasing with height and radially from the phloem to the heartwood boundary. Inorganic arsenic appears to be translocated differently than MSMA, but the elevated levels of inorganic arsenic compounds in the treated tree can be attributed to an impurity in the commercial herbicide. Water content was not correlated with distribution of arsenic. The role of arsenic in the development of lethal trap trees is considered in terms of the translocation of the herbicide, its subsequent chemical fate, and the toxicities of the various arsenic compounds identified in the treated tree. These data strongly suggest that arsenic has a direct insecticidal impact on bark beetle survival.

Bionomics of Pissodes nemorensis Germar (Coleoptera: Curculionidae) in Northern Florida

Brood development and adult activity of Pissodes nemorensis Germar were studied in slash pine ( Pinus elliottii Engelm. var. elliottii ) plantations in northern Florida in 1977-78. The insect is basically univoltine in this area, but immatures are present in infested hosts for almost 9 mo during the cooler part of the year. Eggs were present in the field from late August until mid March; most oviposition occurred from October through February. Development from egg to adult within hosts required 7-25 wk depending on date of oviposition. Most adults emerged from late March to mid May. Some adults emerged before December from eggs laid in late summer, but it is not known whether these reproduced during the same season. Adults were caught in sticky traps next to trap trees, in window traps, and in pheromone traps from August until early April, with a major peak in October or November and a smaller peak in March. Most adults trapped were apparently mature (i.e., had developed in the previous season), for trap catches declined as new adults emerged. Adults were not observed in the summer months and were not caught in traps. P. nemorensis has five instars. At constant temperatures of 15, 20, and 25°C, egg-to-adult development required ca. 180, 70, and 58 d, respectively. Principal causes of mortality to weevil brood were the parasite Coeloides pissodis (Ashmead) (Hymenoptera: Braconidae) and woodpeckers. Disease and competition, principally with Ips spp., also appeared to be important.

COMPARISON OF INSECT FAUNA CAPTURED IN SIX DIFFERENT TRAP TYPES IN A DOUGLAS-FIR FOREST

AbstractInsects were sampled in a Douglas-fir forest in California to evaluate differences among inexpensive survey methods. Sampling was done with sweep nets and with window, sticky, light, suspended cone, and two kinds of yellow pan traps. Also examined were effects of trap location in the given tree and the following tree species: Douglas-fir (Pseudotsuga menziesii Franco), canyon live oak (Quercus chrysolepis Liebm.), tanoak (Lithocarpus densiflorus Rehd.), Pacific madrone (Arbutus menziesii Pursh.), and big-leaf maple (Acer macrophyllum Pursh.). Relative abundance and faunistic similarity of the 9662 insects caught varied greatly by trap type and little by tree species or trap location. Family-level taxonomic richness differed among the diverse trap types, tree species, and trap locations.

Phototactic response of Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) to yellow-coloured surfaces, and an attempt at commercial suppression using yellow barriers and trap trees

AbstractTrioza erytreae (Del Guercio), the vector of the serious citrus greening disease, was found to be highly attracted to yellow surfaces, particularly fluorescent yellow-green (about 530 nm). The phototactic response was used to develop a monitoring trap using 3M Saturn Yellow self-adhesive tape adhering to a glass or Perspex sheet. Transparent PVC foils smeared with a thin layer of clear polybutene were clipped in position over the Saturn Yellow surface and acted as the sticky catchment surface. A spectroradiometric comparison of new and weathered traps indicated only a 10% decrease in reflectance after one year. The traps were a sensitive indicator of psylla abundance. Valencia orchards in the Transvaal, South Africa, supported higher population levels than did navel orchards. A mass-trapping experiment was also done, and involved a cordon of yellow sticky polyethylene strips (Gundle Flexipipe smeared with polybutene) placed around an orchard. This perimeter barrier was combined with aldicarb-treated trap trees within the orchard in an attempt to reduce further the already low psylla numbers. Inside the experimental area there was no statistically significant drop in psylla numbers compared with the control trees outside. These poor economic results making use of the flight response of T. erytreae suggest that carefully integrated biological and chemical suppression of the psylla vector is at present the most practical entomological method for containing greening disease on mature trees.

Trap trees for elm bark beetles

European elm bark beetles,Scolytus multistriatus (Marsh.), were strongly attracted to American elms,Ulmus americana L., baited with theS. multistriatus attractant, multilure, or killed by injection of the arboricide, cacodylic acid; a combination of the two treatments was most attractive. Comparisons of beetle catches on sticky bands affixed to the trees with samples of bark from the same trees showed that the number of beetles landing on cacodylic acid-treated trees was approximately 40 times greater than the number boring into them. Spraying the bark with the insecticide chlorpyrifos had no direct effect on attraction. No live bark beetle brood was found in trees that had been treated with cacodylic acid or chlorpyrifos, but trees that were only baited or left untreated (check) were attacked, killed, and colonized. We suggest that the contribution of the cacodylic acid trap tree technique to Dutch elm disease control will be enhanced by baiting treated trees with multilure and spraying their lower boles with 0.5% chlorpyrifos. This treatment will eliminate diseased and unwanted elms as potential breeding material and kill large numbers of elm bark beetles that might otherwise innoculate healthy elms with the Dutch elm disease fungus.

Behavioral responses of elm bark beetles to baited and unbaited elms killed by cacodylic acid

Diseased elms, treated with various doses of cacodylic acid in northwest England, became attractive to elm bark beetles (Coleoptera: Scolytidae). This attraction seemed to be independent of pheromone baits. However attractive the trees became, they were unsuitable to the beetles as breeding sites since significantly more beetles visited the trees than were stimulated to penetrate and attempt to breed. It seems as if colonization of trap trees by the bark saprophytePhomopsis oblonga following cacodylic acid treatment made the trees unsuitable to beetles for breeding.

Insecticides for Control of Bark Beetles that Spread Dutch Elm Disease

Chlorpyrifos, carbaryl and methoxychlor were compared for the following uses against elm bark beetles: 1, elimination of broods in infested elm wood; 2, exclusion of colonization of uninfested elm logs; 3, toxicity to beetles "landing" on treated elm bark; 4, prophylaxis against twig feeding. Chlorpyrifos killed virtually 100% of the beetle broods, completely excluded colonization of uninfested logs and was toxic to 90% or more of the beetles exposed for 10 seconds to bark sprayed 6 weeks earlier. Methoxychlor ranked second in inflicting mortality on beetle brood and it excluded colonization of green logs, but it was marginally toxic to "landing" beetles. Although less toxic than chlorpyrifos, methoxychlor was superior for suppressing twig-feeding by European elm bark beetles. Carbaryl ranked third in effectiveness in all of these tests. We conclude that chlorpyrifos applied at 0.5% can be an alternative to burning or burying elm wood and that the effects of trap trees can be considerably enhanced by this treatment. Healthy elms can be made prophylactic to branch-feeding or overwintering native elm bark beetles by treatment with chlorpyrifos. However, owing to its repellancy, methoxychlor remains the insecticide of choice to protect healthy elms in regions where the European elm bark beetle is the dominant Dutch elm disease vector.

SCOLYTIDAE ASSOCIATED WITH FELLED WHITE SPRUCE IN ALASKA

AbstractPheromone baited traps and trap trees attracted an aggregate of 29 scolytid species associated with white spruce in three localities in Alaska. Species diversity was higher in the Fairbanks (lat. 64°45′) area than in the Brooks Range (lat. 68°15′) or Kenai Peninsula (lat. 60°37′). Scolytids were found inhabiting all bark-producing areas of the tree from the roots to small branches with the highest density in the tree bole. The most abundant scolytids were Ips perturbatus (Eichhoff), Ips tridens tridens (Mannerheim), Polygraphus rufipennis (Kirby), Dryocoetes affaber (Mannerheim), Trypodendron lineatum (Olivier), and Scolytus piceae (Swaine).

Influence of natural enemies on theSirexwood wasp in herbicide-treated trap trees of radiata pine in north-eastern Victoria

From 1979 to 1982 in north-eastern Victoria, interactions between the European tree-killing wood wasp Sirex noctilio, the parasitic nematode Deladenus siricidicola, and the parasitoids Ibalia leuco...

Immigration, Frequency Distributions and Dispersion Patterns of the Psyllid Trioza erytreae (Del Guercio) in a Citrus Orchard

SUMMARY A citrus orchard at Nelspruit, South Africa was pruned back to the main branches to stimulate the growth of new shoots which are highly attractive to the psyllid Trioza erytreae (Del Guercio). Adults invaded the orchard in exponentially increasing numbers, which led to an exponential increase in number of shoots supporting eggs. In terms of area, there was an increase of 4% of new trees infested per day. The frequency distribution of the first immigrants was random, leading later to extreme contagion. A Poisson model fitted the first sampling date, and the negative binomial the second. After that, the frequency distribution curve was too skew for the negative binomial to fit. The log-normal was the only model to fit all sampling dates. Its standard deviation, which represents the increase in contagion, increased linearly with time. The value of b in a variance/mean plot (Taylor's power law) was 1.69 for this species. Dispersion patterns showed that adults tended to accumulate in the row adjacent to the source of infestation and along the edge bordered by large silver oaks, Grevillea robusta A. Cunn., commonly used as windbreaks. Short shoots supported no or only a few psylla, while long shoots supported zero to many tens of psylla. Valencia seems to be the most attractive variety to this species, while grapefruit was the least attractive and navel and Ortanique intermediate. These results suggest that trap trees in the form of heavily-pruned Valencias treated with an insecticide may be one way to manage T. erytreae populations.

Semiochemicals for the mountain pine beetle, Dendroctonusponderosae (Coleoptera: Scolytidae), in British Columbia: baited-tree studies

Lodgepole pines, Pinuscontorta var. latifolia Engelm., in three interior British Columbia locations were baited with six monoterpenes alone or combined, and various combinations of the beetle-produced volatiles trans-verbenol, exo-brevicomin, and 3-caren-10-ol. Trees baited with trans-verbenol, exo brevicomin, and the monoterpene 3-carene sustained higher attack densities by the mountain pine beetle, Dendroctonusponderosae Hopkins, and were surrounded by more attacked trees than trees baited with trans-verbenol and 3-carene or unbaited controls. Myrcene was apparently the best of six monoterpenes as a synergist for trans-verbenol. 3-Caren-10-ol appeared to have some activity in an early test but did not prove to be an attractive pheromone in extensive studies. In a 17-ha portion of an infestation, treatment of 99 trees with 3-carene and trans-verbenol apparently caused a higher attack rate, resulting in 56.4% of the available green trees being attacked, as opposed to 22.3% of the available trees in the 14-ha unbaited area. These data as well as the high attack rates associated with trees which also had an exo-brevicomin bait suggest that semiochemicals could be used to contain D. ponderosae infestations and to attract beetles to lethal trap trees.

EMERGENCE OF DENDROCTONUS RUFIPENNIS (COLEOPTERA: SCOLYTIDAE) FROM BURIED LOGS

The spruce beetle, Dendroctonus rufipennis (Kirby), causes periodic, widespread mortality of mature spruce (Picea spp.) in western North America (Massey and Wygant 1954; Schmid and Frye 1977). In British Columbia, logging of infested stands and felling of trap trees are the commonly recommended methods for preventing or suppressing spruce beetle outbreaks. Implicit in these methods is the requirement of treating infested logging residue, and removal for processing of trap trees after the attack period of the spruce beetle. The usual treatment for infested logging residue, prescribed burning, is difficult to carry out in most years because of the generally wet climate of spruce forests during the growing season and the fall period. The forest industry questioned whether burying infested logging residue would be effective in preventing emergence by the spruce beetle. The work described herein addressed this question.

Field Evaluation of Pheromone-Baited Trap Trees to Control Elm Bark Beetles 1 , Vectors of Dutch Elm Disease 2

Over 250 diseased or unwanted elm trees ( Ulmus americana ) were killed with the herbicides cacodylic acid (Silvisar 510®) or MSMA (Silvisar 550®), applied either to axe-frills or by pressure injection. Elms thus poisoned and baited with the pheromone “multilure,” were mass-attacked by elm bark beetles but more than 87% of the potential brood was effectively eliminated. A decline in the Dutch elm disease rate accompanied brood elimination. We suggest that this trap tree technique will make a positive contribution to Dutch elm disease control programs by enhancing existing sanitation procedures and allowing tree removal to proceed in an orderly manner, rather than on the urgent schedule now necessary to prevent new infections vectored by emerging beetles.

Colonisation of twelve species of Eucalyptus by Phoracantha semipunctata (F.) (Coleoptera: Cerambycidae) in Malawi

AbstractFelled logs of twelve species of Eucalyptus were exposed simultaneously to attack by Phoracantha semipunctata (F.) in Malawi. Colonisation was assessed by counting the number of larval feeding channels on the surface of the sapwood. The level of colonisation varied significantly between different tree species. E. fastigata and E. paniculata were much more heavily colonised than any of the other species. Possible factors contributing to this variation in susceptibility are discussed. The more susceptible species should be the most efficient for control operations involving the use of trap trees.