Dendrosoter protuberans (Nees) was introduced into the United States from France as a possible addition to the existing spectrum of hymenopterous parasites of the smaller European elm bark beetle, Scolytus multistriarus (Marsham). D. protuberans is an external parasite; it oviposits through bark onto or next to late-instar larvae of S. multistriatus (Kennedy 1970) (Fig. 1)

Kennedy, Bruce H

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Oviposition by \u3ci\u3eDendrosoter Protuberans\u3c/i\u3e (Hymenoptera: Braconidae) on Larvae of \u3ci\u3eScolytus Multistriatus\u3c/i\u3e (Coleoptera: Scolytidae) Occupied by Larvae of \u3ci\u3eEntedon Leucogramma\u3c/i\u3e (Hymenoptera: Eulophidae)

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The Great Lakes Entomologist Volume 14 Number 2 - Summer 1981 Number 2 - Summer 1981 Article 6 June 1981 Oviposition by Dendrosoter Protuberans (Hymenoptera: Braconidae) on Larvae of Scolytus Multistriatus (Coleoptera: Scolytidae) Occupied by Larvae of Entedon Leucogramma (Hymenoptera: Eulophidae) Bruce H. Kennedy USDA Northeastern Forest Experiment station Follow this and additional works at: https://scholar.valpo.edu/tgle  Part of the Entomology Commons Recommended Citation Kennedy, Bruce H. 1981. "Oviposition by Dendrosoter Protuberans (Hymenoptera: Braconidae) on Larvae of Scolytus Multistriatus (Coleoptera: Scolytidae) Occupied by Larvae of Entedon Leucogramma (Hymenoptera: Eulophidae)," The Great Lakes Entomologist, vol 14 (2) Available at: https://scholar.valpo.edu/tgle/vol14/iss2/6 This Peer-Review Article is brought to you for free and open access by the Department of Biology at ValpoScholar. It has been accepted for inclusion in The Great Lakes Entomologist by an authorized administrator of ValpoScholar. For more information, please contact a ValpoScholar staff member at scholar@valpo.edu. THE GREAT LAKES ENTOMOLOGIST OVlPOSlTlON BY DENDROSOTER PROTUBERANS (HYMENOPTERA: BRACONIDAE) ON LARVAE OF SCOLMUS MULTISTRIATUS (COLEOPTERA: SCOLYTIDAE) OCCUPIED BY LARVAE OF ENTEDON LEUCOGRAMMA (HYMENOPTERA: EULOPHIDAE) Bruce H. ~ e n n e d ~ l  Dendrosoter protuberans (Nees) was introduced into the United States from France as a possible addition to the existing spectrum of hymenopterous parasites of the smaller Euro- pean elm bark beetle, Scolytus multistriarus (Marsham). D .  protuberans is an external parasite; it oviposits through bark onto or next to late-instar larvae of S. multistriatus (Kennedy 1970) (Fig. 1). The biology of Entedon leucogramma Ratzeburg has been described by Beaver (1%6). E .  leucogramma is an endoparasite of S. mulrisrriatus. The female of E.  leucogramma enters the egg gallery as it is being developed by the female bark beetle and oviposits in newly deposited bark beetle eggs. The female wasp advances into and retreats from the bark beetle egg gallery as the female bark beetle works in and out of the gallery. The larva of E .  leucogramma develops internally in the larva of S. mulrisrriatus as the latter matures. As the larva of S.  multistriatus matures to a late instar, the parasite larva completes development, emerges from the remains of the bark beetle larva, and pupates. (Figs. 2 and 3.) The purpose of this paper was to find out if D. protuberans oviposits on late-stage larvae of S.  multistriatus already parasitized internally with a larva of E .  leucogramma. Fig. 1. Ovipositing adult female of D. protuberans. 'USDA Northeastern Forest Experiment Station, Forestry Sciences Laboratory, Delaware, OH 43015. 1Kennedy: Oviposition by <i>Dendrosoter Protuberans</i> (Hymenoptera: BracoPublished by ValpoScholar, 1981110 THE GREAT LAKES ENTOMOLOGIST Vol. 14, No. 2 Fig. 2. Normal larva of S. rnultistriatus (right); larval bag of S. multismriamus (left); larva of E. leuco- gramma (middle). Bar = 1.75 mm. Fig. 3. Pupa and adult of E. leucogramma. Bar - 1.0 mm. 2The Great Lakes Entomologist, Vol. 14, No. 2 [1981], Art. 6https://scholar.valpo.edu/tgle/vol14/iss2/6THE GREAT LAKES ENTOMOLOGIST METHODS Seventeen bolts, each approximately 25.4 cm long and 5.0 cm in diameter, were cut from elm wood infested with larvae of S. multistriatus under natural conditions, some of which were parasitized by E. leucogramma. The bolts were exposed individually to varying num- bers (12 to 40) of mated D. protuberans for 24 to 72 h. The bolts were dissected and larvae of S. multistriatus with eggs of D. protuberans (Group A) and those without eggs (Group B) were separated. The eggs of D. protuberans were counted and immediately removed from Group A. On those bolts that were not dissected until 72 h, some D. protuberans larvae emerged from the eggs and were present on some of the beetle larvae (Group C); these parasite larvae also were removed, and the beetle larvae held separately. The beetle larvae in the three groups were kept in petri dishes on moistened filter paper until the study was concluded. RESULTS A total of 1,905 S. multistriatus larvae were removed from the dissected elm bolts; 727 had one or more eggs of D. protuberans on or next to them. The beetle larvae in Group A yielded 4 1 adults plus seven defective (incomplete metamorphosis) individuals of E. leucogramma. Group B larva (1,034) yielded 60 adults of E. leucogramma plus nine defective individuals of E. leucogramma. Additionally, 95 larvae of S. multistriatus from which early-instar larvae of D. protuberans were removed (Group C) yielded 11 adults and two defective individuals of E. leucogramma. A group of 18 larvae of S. multistriatus, each showing an internal late-stage larva of E. leucograrnma (Fig. 4), were oviposited on by D. protuberans. These beetle "larval bags" Fig. 4. Larval bag of S. multistriatus with internal larva of E. leucogramma and egg of D. protuberans. 3Kennedy: Oviposition by <i>Dendrosoter Protuberans</i> (Hymenoptera: BracoPublished by ValpoScholar, 1981112 THE GREAT LAKES ENTOMOLOGIST Vol. 14, No. 2 yielded six adults and 12 defective individuals of Entedon. Also 22 larvae of S. multistriatus, each showing an internal larva of E. leucogramma but no oviposition by D. protuberans, yielded 19 adults and three defective individuals of E. leucogramma. A group of nine S. multistriarus larval bags containing E. leucogramma were removed from an elm bolt and observed; each bag had an attached egg of D .  protuberans. Eight of the nine eggs of D. protuberans hatched (one egg disappeared), and the larvae ofD. proruberans remained on the bags until the larvae of E .  leucogratnma emerged. After the E .  leucogramma larvae emerged, the D .  protuberans larvae desiccated and died. From the original nine beetle bags, seven larvae of E .  leucogramma emerged, pupated, and yielded adults. One larva of E. leucogramma partially emerged and died. Another emerged from the larval bag, partially pupated, and died. Of the S. multistriatus larvae removed from the dissected logs, 53 had two D .  protuberans eggs, 31 had three eggs, 10 had four eggs, and five larvae had six eggs. Fouteen pupae of Cheiropachus colon (L.). a parasite of S.  multistriarus, were removed from the dissected elm bolts, as were 16 larvae and two pupae of E. leucogramma. All were free of eggs or larvae of D. protuberans. D. protuberans oviposited on 44.6% of the S. multistriatus larvae (including larval bags) removed from the elm bolts and 9.4% of the S. multistriatus larvae were parasitized by E .  leucogramma. Of those beetle larvae from which E. leucogranztna emerged, 49.2% were oviposited on by D. protuberans. E. leucogramma larvae emerged from the remains of the S. rnultistriatus larvae in 2 to 7 days. Pupation occurred in 2 to 13 days and adults emerged in 10 to 17 days. Incomplete development of larvae of E .  leucogramma might be attributed to the probing of the ovipositor of D .  protuberans during oviposition, even if no egg is deposited. Larvae of S .  multisrriarus on which oviposition by D .  proruberans has occurred usually are quiescent, as  if stung and paralyzed. Incomplete development of larvae and pupae of E .  leucogramma could be due to activity of early-instar larval feeding by D .  protuberans, even though the larvae of E. leucogramma eventually emerge from the larval bag. In this study, D. protuberans oviposited on beetle larvae previously parasitized by E. leucogramma. The survival of an E .  leucogramma larva when oviposition by another para- site occurs on its host may depend on its stage of development within the host. When the E .  leucogramma larva has reached the larval bag stage, its chances for survival may be greater than if oviposition by another parasite occurs at an earlier stage of development. Under natural conditions, parasitism of S. multistriatus by E .  leucogramma might be obscured by subsequent oviposition by D .  protuberans or, for that matter, by C. colon or by Spathius benefactor Matthews. another parasite of S.  multistriatus. The latter two parasites are well established in S. nzultistriatus populations, but their relationship with E. leucogramma was not investigated in this study. It is also possible that parasitism by the aforementioned parasites might be obscured by the survival of E .  leucogranznza following oviposition by the secondary parasite. LITERATURE CITED Beaver, R. A. 1966. The biology and immature stages of Entedon leucogranznza (Hymenoptera: Eulophidae), a parasite of bark beetles. Proc. Royal Entomol. Soc. London Ser. A. Gen. Entomol. 41:3741. Kennedy, B. H. 1970. Dendrosoter protuberans (Hymenoptera: Braconidae), an introduced larval parasite of Scolytus multistriatus. Ann. Entomol. Soc. Amer. 63:351-358. 4The Great Lakes Entomologist, Vol. 14, No. 2 [1981], Art. 6https://scholar.valpo.edu/tgle/vol14/iss2/6

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Oviposition by \u3ci\u3eDendrosoter Protuberans\u3c/i\u3e (Hymenoptera: Braconidae) on Larvae of \u3ci\u3eScolytus Multistriatus\u3c/i\u3e (Coleoptera: Scolytidae) Occupied by Larvae of \u3ci\u3eEntedon Leucogramma\u3c/i\u3e (Hymenoptera: Eulophidae)

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