Diprion Similis Research Articles

Whole-genome resequencing data support a single introduction of the invasive white pine sawfly, Diprion similis.

Biological introductions are unintended "natural experiments" that provide unique insights into evolutionary processes. Invasive phytophagous insects are of particular interest to evolutionary biologists studying adaptation, as introductions often require rapid adaptation to novel host plants. However, adaptive potential of invasive populations may be limited by reduced genetic diversity-a problem known as the "genetic paradox of invasions." One potential solution to this paradox is if there are multiple invasive waves that bolster genetic variation in invasive populations. Evaluating this hypothesis requires characterizing genetic variation and population structure in the invaded range. To this end, we assemble a reference genome and describe patterns of genetic variation in the introduced white pine sawfly, Diprion similis. This species was introduced to North America in 1914, where it has rapidly colonized the thin-needled eastern white pine (Pinus strobus), making it an ideal invasion system for studying adaptation to novel environments. To evaluate evidence of multiple introductions, we generated whole-genome resequencing data for 64 D. similis females sampled across the North American range. Both model-based and model-free clustering analyses supported a single population for North American D. similis. Within this population, we found evidence of isolation-by-distance and a pattern of declining heterozygosity with distance from the hypothesized introduction site. Together, these results support a single-introduction event. We consider implications of these findings for the genetic paradox of invasion and discuss priorities for future research in D. similis, a promising model system for invasion biology.

Diprion similis (white pine sawfly)

Diprion similis (white pine sawfly)

Sex Pheromone of the Introduced Pine Sawfly, Diprion similis, Revisited to Define a Useful Monitoring Lure: Deviating Chiral Composition and Behavioural Responses Compared to Earlier Reports.

Simple SummaryLarvae of sawflies within the family Diprionidae feed on conifer needles and can cause significant damage to a tree by reducing its growth rate and even causing its death. In forest protection, it is therefore important to make use of various tools to detect the potentially harmful species, and the chemical signals emitted by female sawflies to attracts males, i.e., sex pheromones, have been identified for several species. However, a very precise natural pheromone is often expensive to produce and formulate, and in this study we investigated if the previously reported superior mixtures of similar substances (stereoisomers) actually improved the trap catches of the introduced pine sawfly, Diprion similis. Our field tests performed in Ontario, Canada, did not verify the necessity of adding other stereoisomers to the main pheromone component, the propanoate of (2S,3R,7R)-3,7-dimethylpentadecan-2-ol, in order to obtain maximum catch. Thus, the main component alone can be used in monitoring programs aiming at detection of the introduced pine sawfly. When testing the threo four-isomer blend, it was as attractive as the main component alone, suggesting that monitoring programs can use this more easily synthesized mixture without losing efficiency. We also highlight the need for renewed investigation of male attraction to various isomeric mixtures previously proposed as the sex pheromones for other diprionids.Extracts of Diprion similis females contained about 15 ng of the sex pheromone precursor 3,7-dimethylpentadecan-2-ol per female. After derivatisation with (S)-2-acetoxypropanoyl chloride, we found that the major stereoisomer in the extract was (2S,3R,7R)-3,7-dimethylpentadecan-2-ol. Small amounts of other stereoisomers of 3,7-dimethylpentadecan-2-ol were also identified in the extract, namely 1% of (2R,3S,7S), 0.3% (2R,3R,7R) and 0.4% of (2R,3R,7S). An unknown fifth substance showed a very similar spectrum to 3,7-dimethylpentadecan-2-ol, both in SIM and full scan mode. None of the earlier suggested behavioural synergistic isomers ((2S,3S,7S), (2S,3S,7R) and (2S,3R,7S)) were detected in the extracts. In field tests in Ontario, Canada, the earlier identified main pheromone component, viz. the propanoate of (2S,3R,7R)-3,7-dimethylpentadecan-2-ol, was tested alone and in combination with other stereoisomers, earlier reported to be synergistic. No synergistic effects were detected and the threo four-isomer blend was as attractive as the pure main compound. Thus, one of the few examples of a diprionid sawfly using more than one substance in its sex pheromone could not be confirmed. The results also suggest that monitoring programs can use the more easily synthesized threo-blend without losing efficiency. Furthermore, the study suggests that other diprionid pheromones may benefit from a reinvestigation, to clarify possible synergistic effects of stereoisomers.

TWO NEW HYMENOPTERAN FINDINGS IN SERBIA: DIPRION SIMILIS (DIPRIONIDAE) AS HOST AND ITS PARASITOID, MONODONTOMERUS DENTIPES (TORYMIDAE)

Two hymenopteran species are reported for the Serbian fauna. Diprion similis, from the family Diprionidae, served as a host for the parasitoid wasp Monodontomerus dentipes, from the family Torymidae. The specimens were collected from Mt. Zlatibor in western Serbia. The parasitoid specimens were reared from the pupal stadium of the host D. similis.

Pupation Site Selection and Enemy Avoidance in the Introduced Pine Sawfly (Diprion similis)

Abstract Insects that pupate on the branches of trees and shrubs suffer mortality from both predators and parasitic wasps. Which natural enemy represents the greater threat and therefore the stronger selection force on pupation site selection depends upon the time of year, the relative abundance of predators versus parasitoids, and the availability of alternative prey or hosts. Predation by foraging birds and mammals is likely to occur most commonly in winter when leaves have fallen, cocoons are conspicuous, and higher quality prey are scarcer. Inaccessibility and crypsis of pupation sites may provide protection from visually hunting predators. Attacks by parasitic wasps, which take place only during warmer months, may not be as easily avoided by inaccessibility or crypsis. We studied the patterns and mortality risks of pupation site selection in Diprion similis (Hymenoptera: Diprionidae; Introduced Pine Sawfly). Cocoons that were smaller than average and situated in relatively inaccessible sites (thinner...

Activity of Bacillus thuringiensis cyt1Ba crystal protein against hymenopteran forest pests

A crystal–spore suspension of PS201T6 was toxic to larvae of Diprion similis (Hymenoptera: Diprionidae). Toxicity was at least in part attributable to the Cyt1Ba crystal protein, as demonstrated by bioassays of solubilized protein produced by Escherichia coli expressing PS201T6’s cyt1Ba gene. PS201T6 reduced survival and growth of D. similis in a 2-week field experiment. In laboratory bioassays, both toxin and parental strain affected Acantholyda erythrocephala (Pamphiliidae), Pikonema alaskensis (Tenthredinidae), and Neodiprion sertifer (Diprionidae), as well as spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae). Affecting insects across at least four orders (Diptera, Coleoptera, Hymenoptera, Lepidoptera), Cyt1Ba has the broadest insecticidal activity spectrum among Bacillus thuringiensis crystal proteins documented to date.

Efficacy of Piper nigrum (Piperaceae) extract for control of insect defoliators of forest and ornamental trees

AbstractThe acute toxicities of an extract obtained from a plant within the Piperaceae family and related synthetic analogues were tested against four common Canadian forest pest insects. The acute toxicity of the extract from black pepper, Piper nigrum L., was assessed after 1, 24, and 72 h by the percent larval mortality. The 24 h LC50 estimates for the P. nigrum extract were (in order of decreasing sensitivity) 0.012% for the introduced pine sawfly, Diprion similis (Hartig) (Hymenoptera: Diprionidae), 0.053% for the forest tent caterpillar, Malacosoma disstria Hubner (Lepidoptera: Lasiocampidae), 0.282% for the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), and 0.998% for the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Torticidae). There was no significant increase in mortality after 72 h. Seventy percent of L. dispar larvae dropped off or moved from branches within 1 h of application of 0.2% P. nigrum extract, indicating that these compounds have a repellent effect. Pipercide and nor-pipercide were more toxic to L. dispar and M. disstria larvae than piperolein A and a P. sarmentosum Roxb. amide 72 h after either oral or topical administration of these compounds. Toxic effects of piperamides were more pronounced by oral ingestion. Ninety percent mortality of L. dispar larvae occurred following an oral dose of 5 µg pipercide in diet, whereas mortality was only 40% following topical treatment at 5 µg pipercide/insect. Whole Piper extracts might be useful for the control of sawflies and tent caterpillars in small-scale applications, based on the demonstrated efficacy and reduced risk potential.

Comparison of the fat allocation patterns in female pine sawflies (Hymenoptera: Diprionidae)

The allocation of fat resources to somatic and reproductive tissues was studied in females of five species of pine sawflies (Diprion pini (L.), Diprion similis (Htg.), Gilpinia frutetorum (F.), Gilpinia pallida (Klug), Neodiprion sertifer (Geoffroy); Hymenoptera, Diprionidae). The soma and eggs of newly emerged females were separated and then put in ether to extract and determine their fat content. The fat allocation patterns differed between species. The gregarious outbreak species D. pini and N. sertifer allocated most of the fat to their eggs, whereas the gregarious non-outbreak species, G. pallida, allocated most to its somatic tissues. No modification of these basic allocation patterns was observed with increasing total fat content. In contrast, the solitary non-outbreak species, D. similis and G. frutetorum, invested equal amounts of fat in soma and eggs, and the proportion allocated to the egg load decreased as total fat content increased. That is, they invested additional resources in somatic tissues. Apparently, outbreak species tend to allocate more fat to reproductive tissues than non-outbreak species.

Diapause Induction in a Kentucky Population of Diprion similis (Hymenoptera: Diprionidae)

Critical photoperiod, sensitive stage for diapause induction, and requirements for termination of diapause were studied in a colony of the introduced pine sawfly, Diprion similis (Hartig), established from a feral Kentucky population. We investigated induction of diapause in the laboratory under photoperiods of 10:14, 11:13, 12:12, 13:11, 14:10, 15:9, and 16:8 (L:D) in the first trial, and added a photoperiod of 9:15 (L:D) in the second trial. Individuals exposed to light periods ≤12:12 (L:D) entered diapause; individuals in a photoperiod > 13:11 (L:D) bypassed diapause. The sensitive stage was determined using reciprocal switches of diapause-inducing (9:15) and non-diapause inducing (16:8) L:D regimes. Our studies indicated that late instars of the introduced pine sawfly are significantly sensitive to photoperiod. Termination of diapause in D. similis did not require a cold or chilling period. All individuals from critical photoperiod trials were kept at 22°C to determine the duration of diapause. Diapausing individuals emerged from the cocoon after 82 to 105 d, compared to 6 to 23 d for individuals not entering diapause.

Genetic Variation in Neodiprion (Hymenoptera: Symphyta: Diprionidae) Sawflies and a Comment on Low Levels of Genetic Diversity within the Hymenoptera

Starch-gel electrophoresis was used to investigate the biochemical genetics of seven species of Neodiprion sawflies and the confamilial Diprion similis (Hartig). Interspecific Rogers' distance coefficients ranged from 0.14 to 0.74. Cladistic and phenetic cluster algorithms are consistent regarding interspecific relationships. Average genetic diversity values do not differ from those in the literature for vertebrate groups, Crustacea, or other hymenopterans. The sawfly heterozygosity value (0.06) differs significantly from those of insects excluding hymenopterans and Drosophila (0.10), and from Drosophila (0.12). Small effective population sizes and inbreeding may account for much of the difference.

Isozymes of the sawflies Neodiprion and Diprion similis: Diagnostic characters and genetic distance

No isozyme markers distinguish between any two of the following, Neodiprion swainei, N. rugifrons or N. dubiosus . Assuming independent sorting of the ACO-A, GPD and SDH loci, N. swainei can be distinguished from the other two with a probability of 99.23% if these three loci are all used. The results from Nei's genetic distance calculation for 13 Neodiprion spp. are generally similar to previous work using morphological and geographic characters, except that: (a) N. taedae linearis and N. pratti are not as close to N. rugifrons as believed; (b) N. nanulus nanulus and N. fulviceps are closer to the other North American species in the lecontei group than they are to the Eurasian N. sertifer , and (c) there is no pattem of relationship between the sertifer group species studied.

Insect Parasites Associated with the Introduced Pine Sawfly, Diprion similis (Hartig) (Hymenoptera: Diprionidae), in North Carolina

The parasitic fauna of Diprion similis in North Carolina was investigated by rearing field-collected cocoons from 1978 to 1982. The fauna is impoverished compared with Wisconsin. The torymid, Monodontomerus dentipes (Dalman), and the eulophid, Dahlbominus fuscipennis (Zetterstedt), were transferred from Wisconsin, and small numbers of three European species of egg parasites were also released. Very high levels of parasitism by M. dentipes were subsequently observed.

Utilization of dry matter and elements by larvae of the sawflies Neodiprion sertifer (Geoff.) and Diprion similis (Hartig) feeding on Scots pine needles

Consumption and proportions of dry matter and various elements utilized by late-instar larvae of Diprion similis (Hartig) and Neodiprion sertifer (Geoff.) feeding on previous years' needles of Scots pine (Pinus sylvestris L.) were determined gravimetrically and by means of cellulose as an indigestible marker substance. The only discrepancy between the two methods was for phosphorus intake by N. sertifer females. Female larvae of D. similis utilized larger proportions of dry matter, nitrogen, and potassium and less phosphorous than female larvae of N. sertifer; both species utilized similar proportions of calcium and magnesium. Combined male–female groups of N. sertifer larvae utilized larger proportions of dry matter, potassium, and magnesium compared with female larvae. The proportions utilized were ranked as follows: nitrogen (50–59%), phosphorous (22–39%), magnesium (15–29%), calcium (9–15%), and potassium (6–17%). Nonpositive sodium budgets precluded calculation of utilization of this element. The proportions of dry matter utilized by these sawflies are similar to those for 10 species of foliage-consuming Hymenoptera and fall toward the lower end of the range of values for phytophagous insects. Nitrogen utilization figures for these sawflies fall within the range of values reported for insects that consume tree foliage.

Morphology and ultrastructure of an intertergal pheromone gland in the abdomen of the pine sawfly Neodiprion sertifer (Insecta, Hymenoptera): a potential source of sex pheromones

An abdominal intertergal gland of the sawfly Neodiprion sertifer was found in both sexes of the sawfly N. sertifer, which is in contrast with Diprion similis, in which the gland is known only from the female. The gland lies laterally on each side of tergite II in the fat body between the tergite wall and trachea and opens into the fold of the arthrodial membrane between tergites II and III. The emission of secretion from the gland is controlled by a muscle opening the gland duct. Expansion of the lateral trachea probably forces the secretion out of the gland's lumen.The intertergal gland is a typical insect epidermal pheromone gland formed by three cell types: glandular, ductule, and hypodermal cells. The glandular cells have microvilli-lined cavities surrounded by numerous mitochondria. From these cavities arise ductules, surrounded by ductule cells, merging into other ductules that open into the lumen of the gland. The hypodermal cells underlie the cuticular walls of the lumen. This scheme is now well-known from many insect species as typical of epidermal pheromone glands with a draining duct. Finally, the possible function of the intertergal gland's secretion is discussed.

EFFECT OF A PHENYL-BENZOYL UREA [l-(4-CHLOROPHENYL)-3-(2,6-DIFLUOROBENZOYL)-UREA] ON DIPRION SIMILIS (HYMENOPTERA: DIPRIONIDAE)

AbstractIngestion of a phenyl-benzoyl urea [1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)-urea] by Diprion similis (Hartig) interferes with molting. At the highest concentration (1% solution) tested, it prevents ecdysis but does not prevent apolysis. The Cuticle of pharate larvae is thinner than normal but the formation of melanin in the cuticle is not inhibited. At a concentration of.01%, ecdysis is usually completed but many survivors fail to feed following the molt. This failure is associated with the accumulation of a fibrous material in the midgut. Prior to the molt, food consumption as measured by faecal output is not impaired.

ChemInform Abstract: SEX PHEROMONE SPECIFICITY IN THE PINE SAWFLIES‐ INTERCHANGE OF ACID MOIETIES IN AN ESTER

AbstractIn Neodiprion lecontei und Neodiprion sertifer ist das Acetat von 3,7‐Dimethylpentadecan‐2‐ol der Hauptbestandteil des Sexuallockstoffsjn Diprion similis ist es das Propionat.

Cellulose content of food and faeces of Diprion similis as an internal marker for determining food consumption and digestibility

The consumption and digestibility of Scots pine (Pinus sylvestris L.) foliage by a diprionid sawfly (Diprion similis (Htg.)) can be determined indirectly by using the cellulose content of needles and faeces as an indigestible marker substance. No difference between figures obtained this way and those obtained by direct gravimetric determinations could be detected. This demonstration was preceded by exploratory studies to determine the feasibility of using lignin or cellulose content of the needles and faeces as the marker. Lignin was not employed because its methoxyl content decreases upon passage through the gut. By comparison with gas–liquid chromatography, the glucose oxidase (EC 1.1.3.4) method was shown to be satisfactory for the quantitative estimation of glucose in hydrolysates of cellulose isolated from needles and faeces.

Potential for suppressing Diprion similis (Hymenoptera: Diprionidae) with pheromone trapping: A population model

SummaryThe virgin female introduced pine sawfly, Diprion similis (Hartig), produces a powerful sex pheromone capable of attracting males. Pending chemical identification of the substance, a pilot study in male annihilation is under consideration. A mathematical model was developed to assess the feasibility of population suppression using pheromone‐baited traps. Departure from preexisting population models resulted chiefly from the arrhenotokous nature of the sawfly. The model predicts alternating sawfly generations which undergo first a large shift in the sex ratio but no population reduction, followed by a large decrease in population size with a moderating sex ratio. Four generations of intensive trapping would theoretically be sufficient to eliminate the sawfly from an isolated area.

Bacteria Associated with the Stomodaea of Certain Nearctic Diprionid Species1

Cocoons of newly emerged introduced pine sawflies, Diprion similis (Htg.), each contain a resin-filled saclike stomodaeum attached to the cast skin of the prepupal molt. Preliminary investigations revealed that the stomodaeal sacs harbored several species of bacteria. This study is concerned only with the bacteria isolated from the foregut, and particularly with their possible role as pathogenic agents against or symbiotes with D. similis. We also postulated that specific associations between bacteria and host insects might indicate a taxonomic tool.

Changes in the Mature Larval Gut of the Introduced Pine Sawfly, Diprion similis (Hartig) (Hymenoptera: Diprionidae) During Transformation1,2

The alimentary canal of the introduced pine sawfly, Diprion similis (Hartig) undergoes considerable cell differentiation and change during its ultimate larval stage. This stage has 2 morphologically distinct periods, the eonymphal and pronymphal (Eliescu 1932). The eonymph of D. similis has a black ocellus, no underlying pupal eye development, and a curled abdominal tip; whereas the pronymph has a clear ocellus surrounded by a black, ringlike ocularium, visible developing compound eye below the ocellus, and a straight abdominal tip. A saclike foregut structure is formed during these periods and, at the same time, reddish-brown granules appear along the length of the mesenteron.