Emergence Data and Artificial Rearing Media for an Aspen Bark Beetle, Trypophloeus Populi (Coleoptera: Scolytidae)

Great Basin Naturalist

Volume 39 Number 2 Article 3

6-30-1979

Emergence data and artificial earingr media for an aspen bark beetle, Trypophloeus populi (Coleoptera: Scolytidae)

David A. Stewart Brigham Young University

Gary M. Booth Brigham Young University

Jerold L. Petty Brigham Young University

Follow this and additional works at: https://scholarsarchive.byu.edu/gbn

Recommended Citation Stewart, David A.; Booth, Gary M.; and Petty, Jerold L. (1979) "Emergence data and artificial earingr media for an aspen bark beetle, Trypophloeus populi (Coleoptera: Scolytidae)," Great Basin Naturalist: Vol. 39 : No. 2 , Article 3. Available at: https://scholarsarchive.byu.edu/gbn/vol39/iss2/3

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. EMERGENCE DATA AND ARTIFICIAL REARING MEDIA FOR AN ASPEN BARK BEETLE, TRYPOPHLOEUS POPULI (COLEOPTERA: SCOLYTIDAE)

David A. Stewart', Cary M. Booth', and Jerold 1,. Petty''^

Abstract.— The aspen bark beetle, Tnjpophloeus populi Hopkins, was studied in nature to determine the number adults. of larvae emerging from galleries. Fifty-five percent of the larvae in aspen galleries in the field developed into An artificial rearing medium for third instar larvae of the beetles was also developed from aspen bark sawdust and nutrient agar. The optimum medium contained a ratio of 1:2 parts of agar to sawdust which gave 70 percent emergence of the beetles and less than 10 percent of adult mortality over the 36 days following emergence.

The bark beetle Tnjpophloeus populi Hop- Counts of the emergence holes per paren- kins has been reported from L3 locahties in tal galley system in previously infested P. North America, 6 of which are in northern tremuloides trees were conducted at both col- Utah (Wood, in preparation). Petty (1977) lecting sites. A transparent 10 cm square grid conducted an in-depth study of the bionomics was randomly placed on the trees to make of T. populi and compared it to another as- the counts. Larvae in parental galleries were pen bark beetle Procnjphalus mucronatus counted as removed from 10 cm square areas (LeConte). Later, T. populi became the focus of infested bark. of a study on the larvicidal effects of the in- Four artificial media were prepared from secticide dimilin on bark beetles (Stewart, the sawdust of aspen bark cut by a radial-arm Booth, and Petty, in preparation). Except for saw, which was then mixed with varying two brief taxonomic studies on European amounts of nutrient agar and autoclaved at Tnjpophloeus (Hagedorn 1904, Palm 1959), 6.8 kg pressure and 110 C for 15 minutes to nothing else has been published on the bio- suppress microorganism activity (Bedard nomics of this genus. 1966). Petri dishes containing 30 grams of the The objectives of this paper are: (1) to re- medium were stored and used at 22 C. The port the development of an artificial medium larvae were transferred into the medium us- for rearing T. populi and (2) to determine the ing strict sterile techniques. percent emergence of T. populi in nature. Results and Discussion Materials and Methods The average number of larvae found per gallery in nature during this study was 14.75 The beetle larvae were collected from two (Table 1). Petty (1977) reported 14 eggs per sites in Utah county, Utah. The first site was primary egg chamber for T. populi and often 1.6 km north of Aspen Grove, and the second found two or three other secondary areas site was 1.8 km north of Aspen Grove. Col- eggs were deposited in smaller lections were made by removing strips of in- where num- bers. However, there was no estimate of the fested Populus tremuloides bark with a hand total number of eggs per gallery. ax. Larvae were then removed in the labora- adult T. exits tory from the bark sections by breaking open Each newly emerging populi the tree boring out, leaving a small larval galleries. from by

'Department of Zoology, Brigham Young University, Provo, Utah 84602. 'Present address: Department of Entomology, Oregon State University, Corvallis, Oregon 97331

129 Vol. 39, No. 2 130 Great Basin Naturalist

the ar- hole in the bark surface to indicate its depar- From 1 to 20 larvae were placed on ture (Petty 1977). By counting these holes, an tificial media. Development data indicate no estimate of the number of adult beetles that significant difference due to number of lar- developed from the larvae was found to be vae at the .05 level using the standard t test. 8.16 per galley (Table 2). Dividing the num- Pure nutrient agar and pure sawdust were ber of exit holes made by emerging adults by compared to the results obtained from the the estimated number of larvae indicates that media. Emergence of the adults occurred 55 percent of the larvae developed into from 21 to 28 days after being placed on the adults that emerged from the tree. media, and pupation occurred at 16 to 21 days. All larvae placed on the media were of the third or final instar as determined by Table 1. Average number of Tnjpophloeiis populi larvae per parental gallery in random 10 X 10 cm squares. head capsule size (Petty 1977). Larvae of the first two instars were also successfully reared Number of Total but records were not kept on them. galleries larvae Larvae per Emergence varied from 1.67 percent of the per sample found gallery

7 7 1979 Stewart et al.: Bark Beetle Bionomics 131

to develop into adults but were unable to caused by changes in moisture content, but feed on the medium and subsequently died no attempt was made to investigate this pos- shortly after (Fig. 1). It is interesting that the sibility. Adults feeding on two parts bark to pure sawdust medium caused 98 percent one part agar and three parts bark to one mortality of the larvae after 36 days. This part agar lived on the medium up to 120 high mortality could have been possibly days. They constructed galleries but oviposi- tion did not occur. 100

70_ 65.45 u 60 ^ Z UJ

45. 40

^ 30 30.63

18.8 15

1.67 13. 2A lA lA lA sawdust 1 B IB 2B 3B MEDIUM of adults QV,'o emergence Vo emerged ^ dead after 36 days A=AGAR B=BARK

Fig. 1. Percent emergence of Trypaphloeiis popiili in artificial media and percent of emerged adults dead after 36 days. Vol. No. 132 Great Basin Naturalist 39,

Summary Literature Cited

Bedard, W. D. 1966. A ground phloem for rearing im- In nature it was estimated that 55 percent mature bark beetles (Scolytidae). Ann. Entomol. produced in a gallery will de- of the larvae Soc. Amer. 59:931-938. velop into adults and emerge. 1904. Biologischer nachtrag zur revi- Hagedorn, J. M. The bark beetle Trypophloeus populi was sion unserer Papelborkenkafer. Mtmchener reared from the third instar larva to the adult Koleopt. Zeitschr. 2:372-373. Palm, T. 1959. Die Holz- und Rinden-kafer der siid- und stage on a medium of nutrient agar and aspen mittelschwendischen laubbaume. Opusc. Ent. of bark sawdust. The optimum concentration Suppl. 16:350-351. parts bark to one part L. 1977. Bionomics of aspen bark beetles, bark to agar was two Petty, J. two agar, with 70 percent of the larvae devel- Trypophloeus populi and Procryphalus miicr- onattts (Coleoptera: Scolytidae). Great Basin Nat. oping into adults. Adults fed on the medium 37:10,5-127. galleries, but mating and ovi- and excavated L. Effect of Stewart, D. A., G. M. Booth, and J. Petty. position were not observed. dimilin on the larvae of an aspen bark beetle Try- pophloeus populi and on the house fly Musca do- mestica. In preparation.

Acknowledgments Wood, S. L. ex 1980. The bark and ambrosia beetles of North and Central America (Coleoptera: Scoly- We wish to acknowledge the expertise and tidae): a taxonomic monograph. In preparation. assistance of Dr. Stephen L. Wood, who of- fered counsel and encouragement throughout the project.