Cram, W. T.

Pearson, W. D.

English

Journal of the Entomological Society of British Columbia

PROC. Ei'lTO:\1OL. Soc . BRIT. C OLUJ\lllIA . VOL. 62 (1965), DEC. 1, 1965 25 FECUNDITY OF THE BLACK VINE WEEVIL, Brachyrhinus sulcatus (F.), FED ON FOLIAGE OF BLUEBERRY, CRANBERRY AND WEEDS FROM PEAT BOGS' W. T. CRAM AND W. D. PEARSON2 Introduction Larvae of the black vine weevil, Brachyrhinus sulcatus (F.), severely damaged roots of blueberry (Cram, 1963), and cranberry grown on well-drained peat bogs on Lulu Island and at Pitt Meadows. Adult weevils were observed feeding, or their feeding damage was seen on these plants and on several weeds of peat bogs. A laboratory study was conducted to determine the suitability of the weeds and the economic plants as hosts of this flightless, partheno-genetic weevil, using as criteria weight gain, preoviposi'tion period, rate of egg laying, and egg viability. Methods Newly-emerged adults were col-lected from the duff under blueberry bushes on Lulu Island in mid-June. Only soft, incompletely hardened weevils were used. Single adults were confined at 20° C with 16 hours of shaded fluorescent light in closed plastiC snap-cap vials (Anglo 2.5 by 9 cm) each with a leaf from a par-ticular plant. Thirteen replicates of seven plant species were started. Foliage was changed at weekly ill-tervals. The amount consumed by each weevil was judged by a ra ti ng scheme. Weevils were weighed when captured, three weeks later, and on the day of first oviposition. Weekly records of total and viable eggs were kept for each weevil. Viability was determined by holding the eggs for four days before counting, by which time the viable eggs had darkened. Counts were dIscontinued in mid-September when oviposition normally ceases in the field (Cram, 1965a) . The data presented are from the first 10 weevils to oviposit in each treat-ment. I Contribution No. 93 Research station, Re· search Branch, Canada Department of Agriculture, 6660 N.W. Marine Drive, Vancouver 8, B.C. 2 Summer student. The plants chosen for study were: Himalaya blackberry, Rubus thyrsan-thus Focke; salal, Gaultheria shallon Pursh; labrador tea, Ledum groen-landicum Oeder.; cranberry, Vaccin-ium macrocarpon Ait. var. MacFar-lane; highbush blueberry, Vaccinium corymbosum (Aust.) var. Rancoccus; fireweed, Epilobium angustijolium (L.); sheep sorrel, Rumex acetosclla L. Selected undamaged current-sea-son fOliage from all but cranberry was collected periodically at the same blueberry plantation on Lulu Island and stored in air-tight plastic bags at 0° C until needed. Cranberry was coUectedfrom a nearby plantation. Results Blackberry and salal produced similar and significan tly grea ter mean weight gains than the other plants 'after three weeks but none gave significantly different weight gains at the time of first oviposition (Table 1) . Blackberry induced a significantly shorter mean preovi-position period than the other plants. Salal and cranberry gave the next shortest followed by labrador tea, fireweed and 'blueberry; no weevils survived to oviposit when fed sheep sorrel. There appeared to be exces-sive moisture in the closed vials con-taining sheep sorrel. The addition of strips of filter paper absorbed the excess moisture but did not halt mortality on this hoS't. Blackberry produced a significant-ly greater mean number of total '1nd viable eggs than other plants (Table 1). Weevils fed blackberry laid more than 2.5 times as many eggs as those fed cranberry and 4 times as many as those fed blueberry. Salal pro-duced significantly more eggs than blueberry or fireweed. There was a significant positive correlation be-tween the number of eggs laid and the viability of the eggs, and a '1> "" a> r-I r-i c.i ~ ~ ~ If:> '.0 0> r-I cq "" ...i o ;;. .;, § '"' ;;, "' :3 ~ ~ il=I c;; o Ul ...i 8 '" o E-< ?; riI c;; o '" 0... "" "" TABLE l.--Means and standard dev1at1ons of we1ght ga1ns, preov1pos1t1on per1ods, numbers of total and v1able eggs and percentages of v1able eggs of B. sulcatus fed excised leaves of var10us plants grow1ng 1n peat bogs on Lulu Island. Plants Blackberry Salal Labrador Tea cranberry Blueberry F1reweed Sheep Sorrel General mean We1ght Ga1ns At 3 weeks mg 23.2 (±3.6)a 1 23.2 (±2.7}a 13.8 (±4.3)bc 17.2 (±6.0)b 15.6 (±4.7)b 11.2 (±5.0)bc 9.4 (±4.0)c 16.2 (±4.5) At f1rst egg mg 24.1 (±5.0)a 22.0 (±3.7)a 24.7 (±3.J}a 22.4 (±6.4)a 20.1 (±4.4)a 20.6 (±6.7)a _2 22.3 Pre-ov 1pos1 t10n Per10ds Days 28 (±2.5)a 35 (±5.8)b 45 (±2.8)c 38 (±3.2}b 48 (±12 .1) c 48 (±7.1)c _2 40 (:9.7) Total 380 (±81.4)a 217 (±105.2)b 165 (±63.9)bc 163 (±132.2)bc 99 (±.58 • .5)cd 53 (±30• 8)d _2 180 Eggs V1able % V1ab111ty 346 (t90.9)a 86 a 187 (±108.9)b 71 ab 150 (±67.7)bc 88 a 133 (±136.')bc 74 ab 72 (±56.6)cd 59 b 32 (±24.6)d 60 b 1.54 73 IMeans w1th1n the same column wh1ch have the same letter are not s1gn1f1cantly d1fferent at the 5% level, Duncan's New Mult1ple Range Test. 2NO surv1vors PHOC. E"TOMOL. Soc . BlIll'. C OLU MIliA. VOL. 62 (1965), DEC. 1, 1965 27 significant negative correlation be-tween weight gain in the first three weeks and the length of the preovi-position period. The amounts of ~he various plants consumed were not judged to differ significantly. Discussion Observations on host selection by adult B. sulcatus indicated that they wander randomly at night and en-counter hosts fortuitously. Trl '::'Y become negatively geotropic at dusk and appear to climb any plant en-countered and feed on the fOliage, hence the wide range of plants show-ing leaf notches. It is not certain t,hat weevils reject unsuitable plants after initial feeding but there is an indication that this might be the case with labrador tea which .suf-fered least from feeding in the fi~ld (Cram, 1965b). Since no significant differences occurred between plants in the amounts of leaf consumed but signi-ficant differences did occur between plants in initial weight gain, preovi-position period and egg production , certain hosts appear to be nutrition-ally superior to others for weevil increase. The best-suited hosts, in-dicated by this laboratory study, appear to be Himalaya blackberry and salal, both serious weeds of blue-berry plantations and the headlands of cranberry bogs. Reduction of these weeds in and around commercial plantations might help appreciably to keep the numbers of the black vine weevil below damaging levels. Summary The roots of blueberry and cran-berry grown in well-drained peat bogs are severely damaged by larvae of the black vine weevil, Brachyr-hinus sulcatus (F.). The adults feed on the foliage of these commercial plants and several weed plants. A laboratory experiment using excised foliage from seven common plants as food for the adults revealed that Himalaya blackberry and salal were significantly superior hosts, on the evidence of shorter preoviposition periods and higher egg production. Inferior hosts in descending order were: labrador tea, cranberry, bl'Je-berry, fireweed and finally sheep sorrel. Adults did not survive to ovi-post when fed sheep sorrel. Removing blackberry and salal in and around commercial plantations of blueberry and cranberry might help appreciably in reducing damage by this pest. References Cram, W. T. 1963. Granular aldrin for control of the black vine weeVil, Brachyrhinus sulcatus (F.l, in establishe d blue berry plantings on p eat in British Columbia . Pesticide Progress 1: 185·187. Cram, W. T. 1965a. Fecundity of the root weevils Brachyrhinus sulcatus and Sciopithes obscurus on strawberry in the laboratory and outdoors. Can. J. Plant Sci. 45 (2): 169·176. Cram, W. T. 1965b. A note on the acceptability of leaf macerates on filter paper of plants from peat bogs by adult black vine weevils, Brachyrhinus sulcatus (F.). Proc. Entomo!. Brit. Columbia 62: 14·15. 

Fecundity of the black vine weevil, Brachyrhinus sulcatus (F.), fed on foliage of blueberry, cranberry and weeds from peat bogs

https://journal.entsocbc.ca/index.php/journal/article/download/1583/1655

Fecundity of the black vine weevil, Brachyrhinus sulcatus (F.), fed on foliage of blueberry, cranberry and weeds from peat bogs

Abstract

Similar works

Full text

Available Versions

Journal of the Entomological Society of British Columbia