Roberts, James E.

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UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 9 Article 5 1956 Spinach and Aphid Control by Ladybird Beetles James E. Roberts University of Arkansas, Fayetteville Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Entomology Commons, and the Plant Pathology Commons Recommended Citation Roberts, James E. (1956) "Spinach and Aphid Control by Ladybird Beetles," Journal of the Arkansas Academy of Science: Vol. 9 , Article 5. Available at: https://scholarworks.uark.edu/jaas/vol9/iss1/5 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. "SPINACH APHID CONTROL BY LADYBIRD BEETLES11James E. RobertsUniversity of ArkansasSome species of aphids have long been recognizedas a favorite food of Ladybird beetle adults and lar-vae. In spite of the tremendous reproductive capa-city of aphids, the Ladybird beetle is capable ofholding aphid populations well incheck under certainnatural conditions.This paper presents results of studies of the spi-nach aphid and the interrelationship of mixed popu-lations of the Ladybird beetle and spinach aphid un-der controlled conditions.MATERIALS AND METHODSLarge Cage for Population StudiesFigure 1presents a picture of a cage constructedin one corner of a green house for the large cageexperiment. The cage was three feet high supportedby legs three feet in length. The sides of the cagewere covered with muslin and the top with "sunraywire," a transparent glass substitute.Figure 2 shows a sketch of the floor plan of thecage. A six-feet -square wooden floor was coveredwith approximately six inches of soil. A sleeve-covered manhole was left in the center of the woodenfloor for entry into the cage. A one-foot-squareduct provided an opening between the cage and an out-side window. The duct was covered at the outer endwith a fine mesh screen to exclude the passage ofinsects. An 8-inch fan installed in the duct wasused to regulate temperature. A thermostat insidethe cage was set to start the fan at 80° F. On dayswhen cage temperature was above 80° F., the fan pulledcooler air in from outside. Recordings of a thermostat11Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 195612ARKANSAS ACADEMY OF SCIENCEFigure 1 Population Study Cage12Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5https://scholarworks.uark.edu/jaas/vol9/iss1/513.SPINACH APHID CONTROL BY LADYBIRD BEETLESFigure 2 Floor Plan of Cage13Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCEI14revealed an average temperature inside of the cageof 74.17° F. for the entire experimental record.Radishes were used as food plants for the aphidsbecause they germinate and grow faster than spinach.Three rows were planted every other day with a totalof 9 plantings or 27 rows. When the total space wasplanted, new plantings were continued by pulling upthe 3 oldest rows. This was done in order to main-tain young plants of a uniform age range.Populations were initiated by the introduction offive newly-matured aphids into the cage. Numbers ofaphids present on nine plants were recorded everyother day. These plants were selected at random fromthe three rows that were pulled up and replanted thatday. The plants that were pulled up were placed ona wire rack inside the cage . No aphids were ever re-moved intentionally from the cage.RESULTSTable 1 presents three columns of related datafrom the large cage study and corresponding mathe-matical calculations.Column two shows counts of aphids per nine plantson the dates listed in column one. Five newly-maturedaphids were introduced on November 9th to initiatetjiis population. Column three represents total num-bers of aphids that may have been present in the cageon the corresponding dates. This column is based oncounts of aphids per nine plants and a close approxi-mation of total plants. Assumption is made thataphids were equally distributed and that plants wereuniform in size. Since aphid counts were made fromthe oldest plants, numbers incolumn three are some-what exaggerated, even though they are based on ac-tual counts. Column four represents a theoreticalcalculation of the potential population which fivenewly-matured spinach aphids could give rise to inthirty-one days. The above calculation is based on14Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5https://scholarworks.uark.edu/jaas/vol9/iss1/5¦15SPINACH APHID CONTROL BY LADYBIRD BEETLESTable 1, The trend of a spinach aphid population inthe absence of natural enemies under largecage conditions.Number aphid s Total aphidsper 9 plants Actual^/ Theoretical^/DateNovember9 0 0 021 2 511 94922 1,31723 34 8,511 1,76024 2,27625 21 5,340 2,86626 3,81427 40 10,217 5,40128 7,91029 482 124,227 11,45930 16,354December1 34 8,591 29,8782 31,2903 456 117,725 41,8994 56,0815 76,2766 854 220,358 106,0347 149,3478 946 243,810 210,8029 295,78810 1,347 347,603 398,89712 607 156,5031314 303 78,2511516 475 122,60218 80 20,6661920 176 45,395y Total population present in cage based on countsin column 2.=/ Calculations of the possible potential population.15Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCE!16Irecords of individual rearing of spinach aphids onradishes. This theoretical calculation was increas-ing at the rate of 103,109 aphids per day by thethirty-first day, which would indicate a fairly closecorrelation between the calculated total populationactually present and the theoretical totals on thatdate.Columns two and three indicate an apparent declineof this population after December 10th, even thoughnatural enemies were completely excluded. Since therewas no obvious reduction in number of aphids presenton the basis of total plant surface area, an expla-nation ofprobable causes of this decline is presentedherewith.Probably the most important factor contributingto the decline in numbers of aphids per plant wa3much smaller plants, hence smaller surface area. Thesmaller plants were apparently caused by both theheavy aphid population and weather conditions un-favorable for plant growth; e.g.,short, cloudy days.The appearance of large numbers of winged aphidsalong with the population peak could well have beena partial cause o f the declining numbers of aphidsper plant. The appearance of winged aphids is nearlyalways accompanied by crowded conditions and/or shor-tage of food. Many of the winged aphids left theplants, and apparently spent the remainder of theirlives on the cage walls. Presumably they were try-ing to escape from the cage, Many of the non-wingedaphids also exhibited a general discontent by con-tinuously crawling about the cage during the popula-tion peak.Table 2 presents records from the spinach aphidpopulation subjected to lady bettles under large cageconditions. Five newly-matured aphids were intro-duced into the cage on January 11, 1955.Column two presents number of aphids per nineplants on the dates listed in column one. Fluctua-tions within this column are closely correlated with16Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5https://scholarworks.uark.edu/jaas/vol9/iss1/5!SPINACH APHID CONTROL BY LADYBIRD BEETLES17absence or presence of lady beetle larva or adults.A mixture of four different species of lady bee-tle adults were introduced into the cage. As shownin column three, these were introduced into the cageat intervals. Many of the first adult beetles in-troduced failed to reproduce. Additional introduc-tions were made at intervals, attempting to providefor the initiation of a lady beetle population thatwould eliminate the aphids present in the cage.Column four presents the number of larvae whichhatched in the cage. Lady beetle eggs were depositedin clusters on the sides and top of the cage. Countsof larvae were made on the date hatching occurred.Newly-hatched larvae remained ina cluster around theegg shells for a few hours.The most obvious result shown in Table 2 is therapid reduction in number of aphids per nine plantsbetween March 10 and March 20. However, the plantsappeared to be very unhealthy, and the aphids seemeddiscontented even before March 10, 1955. Hence theaphid population would have probably taken a down-ward trend at this point without the effect of naturalenemies, as shown in Table 1.Hippodomia converg ens (Guer) was the most preva-lent species of lady beetle introduced into the cage.According to observations by Clausen (1) an indivi-dual of this species consumed an average of 349 aphidsduring the larva], period and 863 during total adultlife. Females lived considerably longer than malesand consumed approximately three times as many aphids.He reports an average of 163 days for the larval per-iod of this species. On the basis of Clausen'sfindings the aphid population could not have beeneradicated by the lady beetles alone if conditionsfavorable for maximum aphid reproduction had existed.Hence the effect of limited plant surface area dueto sickened and smaller plants surely favored theeradication of aphids by the lady beetles present.Nevertheless, the presence of lady beetles, es-17Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCE18Table 2. The effect of lady beetle adults and larvaupon a spinach aphid population under largecage conditions.Number „ . ... NumberNumber adultDate aphids perTuoV, newly hatched9 plants L' B' introduced L>B> larvaeJanuary11 022 1524 1726 iS28 10430 109February1 3063 3966295 3527 5289 770 244311 87113 1,00115 48917 573 5 First adults emergefrom pupae19 35721 28123 5796525 34527 501March1 289 52 34 adults presentin cageI 439 4 25919 308 2,01010 2,' 53812 1,620296607614 281516 28 3218 9 2420 022 018Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5https://scholarworks.uark.edu/jaas/vol9/iss1/5SPINACH APHID CONTROL BY LADYBIRD BEETLES19pecially the larval stage, seemed to be very effec-tive in holding the aphid population in check. Onthe basis of a l6-day larval feeding period, the 85larvae which hatched between February 9 and February13 may have consumed an average of 1,483 aphids perday or a total of 29,665 aphids. This potential con-sumption of aphids by lady beetle larvae plus helpfrom lady beetle adults present would account forthe -progressively lower counts of aphids- per niaeplants between February 13 and March 1* The 214 ladybeetle larvae which hatched between March 4and March18 may have consumed an average of 2,919 per day ora total of 87,599 aphids.SUMMARYThe spinach aphid has a tremendous reproductivecapacity. As the population increases, plants be-come progressively unhealthy and stunted under largecage conditions. Potential increase of aphids isthen checked by lack of sufficient plant surface area.Lady beetle adults and larvae can rapidly reducea population of spinach aphids when present in suf-ficient numbers. Plants recover amazingly fast whenfreed of aphids.LITERATURE CITED1. Clausen, C. P. 1916. Life History and FeedingRecords of a Series of California Coccinellidae.Univ. of Calif. Pub. Tech. Buls. Vol. 1No. 6:251-299.19Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956

Spinach and Aphid Control by Ladybird Beetles

ScholarWorks@UARK

Journal of the Arkansas Academy of ScienceVolume 9 Article 51956Spinach and Aphid Control by Ladybird BeetlesJames E. RobertsUniversity of Arkansas, FayettevilleFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Entomology Commons, and the Plant Pathology CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academyof Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationRoberts, James E. (1956) "Spinach and Aphid Control by Ladybird Beetles," Journal of the Arkansas Academy of Science: Vol. 9 , Article5.Available at: http://scholarworks.uark.edu/jaas/vol9/iss1/5"SPINACH APHID CONTROL BY LADYBIRD BEETLES11James E. RobertsUniversity of ArkansasSome species of aphids have long been recognizedas a favorite food of Ladybird beetle adults and lar-vae. In spite of the tremendous reproductive capa-city of aphids, the Ladybird beetle is capable ofholding aphid populations well incheck under certainnatural conditions.This paper presents results of studies of the spi-nach aphid and the interrelationship of mixed popu-lations of the Ladybird beetle and spinach aphid un-der controlled conditions.MATERIALS AND METHODSLarge Cage for Population StudiesFigure 1presents a picture of a cage constructedin one corner of a green house for the large cageexperiment. The cage was three feet high supportedby legs three feet in length. The sides of the cagewere covered with muslin and the top with "sunraywire," a transparent glass substitute.Figure 2 shows a sketch of the floor plan of thecage. A six-feet -square wooden floor was coveredwith approximately six inches of soil. A sleeve-covered manhole was left in the center of the woodenfloor for entry into the cage. A one-foot-squareduct provided an opening between the cage and an out-side window. The duct was covered at the outer endwith a fine mesh screen to exclude the passage ofinsects. An 8-inch fan installed in the duct wasused to regulate temperature. A thermostat insidethe cage was set to start the fan at 80° F. On dayswhen cage temperature was above 80° F., the fan pulledcooler air in from outside. Recordings of a thermostat11Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 195612ARKANSAS ACADEMY OF SCIENCEFigure 1 Population Study Cage12Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5http://scholarworks.uark.edu/jaas/vol9/iss1/513.SPINACH APHID CONTROL BY LADYBIRD BEETLESFigure 2 Floor Plan of Cage13Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCEI14revealed an average temperature inside of the cageof 74.17° F. for the entire experimental record.Radishes were used as food plants for the aphidsbecause they germinate and grow faster than spinach.Three rows were planted every other day with a totalof 9 plantings or 27 rows. When the total space wasplanted, new plantings were continued by pulling upthe 3 oldest rows. This was done in order to main-tain young plants of a uniform age range.Populations were initiated by the introduction offive newly-matured aphids into the cage. Numbers ofaphids present on nine plants were recorded everyother day. These plants were selected at random fromthe three rows that were pulled up and replanted thatday. The plants that were pulled up were placed ona wire rack inside the cage . No aphids were ever re-moved intentionally from the cage.RESULTSTable 1 presents three columns of related datafrom the large cage study and corresponding mathe-matical calculations.Column two shows counts of aphids per nine plantson the dates listed in column one. Five newly-maturedaphids were introduced on November 9th to initiatetjiis population. Column three represents total num-bers of aphids that may have been present in the cageon the corresponding dates. This column is based oncounts of aphids per nine plants and a close approxi-mation of total plants. Assumption is made thataphids were equally distributed and that plants wereuniform in size. Since aphid counts were made fromthe oldest plants, numbers incolumn three are some-what exaggerated, even though they are based on ac-tual counts. Column four represents a theoreticalcalculation of the potential population which fivenewly-matured spinach aphids could give rise to inthirty-one days. The above calculation is based on14Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5http://scholarworks.uark.edu/jaas/vol9/iss1/5¦15SPINACH APHID CONTROL BY LADYBIRD BEETLESTable 1, The trend of a spinach aphid population inthe absence of natural enemies under largecage conditions.Number aphid s Total aphidsper 9 plants Actual^/ Theoretical^/DateNovember9 0 0 021 2 511 94922 1,31723 34 8,511 1,76024 2,27625 21 5,340 2,86626 3,81427 40 10,217 5,40128 7,91029 482 124,227 11,45930 16,354December1 34 8,591 29,8782 31,2903 456 117,725 41,8994 56,0815 76,2766 854 220,358 106,0347 149,3478 946 243,810 210,8029 295,78810 1,347 347,603 398,89712 607 156,5031314 303 78,2511516 475 122,60218 80 20,6661920 176 45,395y Total population present in cage based on countsin column 2.=/ Calculations of the possible potential population.15Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCE!16Irecords of individual rearing of spinach aphids onradishes. This theoretical calculation was increas-ing at the rate of 103,109 aphids per day by thethirty-first day, which would indicate a fairly closecorrelation between the calculated total populationactually present and the theoretical totals on thatdate.Columns two and three indicate an apparent declineof this population after December 10th, even thoughnatural enemies were completely excluded. Since therewas no obvious reduction in number of aphids presenton the basis of total plant surface area, an expla-nation ofprobable causes of this decline is presentedherewith.Probably the most important factor contributingto the decline in numbers of aphids per plant wa3much smaller plants, hence smaller surface area. Thesmaller plants were apparently caused by both theheavy aphid population and weather conditions un-favorable for plant growth; e.g.,short, cloudy days.The appearance of large numbers of winged aphidsalong with the population peak could well have beena partial cause o f the declining numbers of aphidsper plant. The appearance of winged aphids is nearlyalways accompanied by crowded conditions and/or shor-tage of food. Many of the winged aphids left theplants, and apparently spent the remainder of theirlives on the cage walls. Presumably they were try-ing to escape from the cage, Many of the non-wingedaphids also exhibited a general discontent by con-tinuously crawling about the cage during the popula-tion peak.Table 2 presents records from the spinach aphidpopulation subjected to lady bettles under large cageconditions. Five newly-matured aphids were intro-duced into the cage on January 11, 1955.Column two presents number of aphids per nineplants on the dates listed in column one. Fluctua-tions within this column are closely correlated with16Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5http://scholarworks.uark.edu/jaas/vol9/iss1/5!SPINACH APHID CONTROL BY LADYBIRD BEETLES17absence or presence of lady beetle larva or adults.A mixture of four different species of lady bee-tle adults were introduced into the cage. As shownin column three, these were introduced into the cageat intervals. Many of the first adult beetles in-troduced failed to reproduce. Additional introduc-tions were made at intervals, attempting to providefor the initiation of a lady beetle population thatwould eliminate the aphids present in the cage.Column four presents the number of larvae whichhatched in the cage. Lady beetle eggs were depositedin clusters on the sides and top of the cage. Countsof larvae were made on the date hatching occurred.Newly-hatched larvae remained ina cluster around theegg shells for a few hours.The most obvious result shown in Table 2 is therapid reduction in number of aphids per nine plantsbetween March 10 and March 20. However, the plantsappeared to be very unhealthy, and the aphids seemeddiscontented even before March 10, 1955. Hence theaphid population would have probably taken a down-ward trend at this point without the effect of naturalenemies, as shown in Table 1.Hippodomia converg ens (Guer) was the most preva-lent species of lady beetle introduced into the cage.According to observations by Clausen (1) an indivi-dual of this species consumed an average of 349 aphidsduring the larva], period and 863 during total adultlife. Females lived considerably longer than malesand consumed approximately three times as many aphids.He reports an average of 163 days for the larval per-iod of this species. On the basis of Clausen'sfindings the aphid population could not have beeneradicated by the lady beetles alone if conditionsfavorable for maximum aphid reproduction had existed.Hence the effect of limited plant surface area dueto sickened and smaller plants surely favored theeradication of aphids by the lady beetles present.Nevertheless, the presence of lady beetles, es-17Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956ARKANSAS ACADEMY OF SCIENCE18Table 2. The effect of lady beetle adults and larvaupon a spinach aphid population under largecage conditions.Number „ . ... NumberNumber adultDate aphids per Tuo V, newly hatched9 plants L' B' introduced L>B> larvaeJanuary11 022 1524 1726 iS28 10430 109February1 3063 3966295 3527 5289 770 244311 87113 1,00115 48917 573 5 First adults emergefrom pupae19 35721 28123 579 6525 34527 501March1 289 52 34 adults presentin cageI 439 4 25919 308 2,01010 2,' 53812 1,620296607614 281516 28 3218 9 2420 022 018Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5http://scholarworks.uark.edu/jaas/vol9/iss1/5SPINACH APHID CONTROL BY LADYBIRD BEETLES19pecially the larval stage, seemed to be very effec-tive in holding the aphid population in check. Onthe basis of a l6-day larval feeding period, the 85larvae which hatched between February 9 and February13 may have consumed an average of 1,483 aphids perday or a total of 29,665 aphids. This potential con-sumption of aphids by lady beetle larvae plus helpfrom lady beetle adults present would account forthe -progressively lower counts of aphids- per niaeplants between February 13 and March 1* The 214 ladybeetle larvae which hatched between March 4and March18 may have consumed an average of 2,919 per day ora total of 87,599 aphids.SUMMARYThe spinach aphid has a tremendous reproductivecapacity. As the population increases, plants be-come progressively unhealthy and stunted under largecage conditions. Potential increase of aphids isthen checked by lack of sufficient plant surface area.Lady beetle adults and larvae can rapidly reducea population of spinach aphids when present in suf-ficient numbers. Plants recover amazingly fast whenfreed of aphids.LITERATURE CITED1. Clausen, C. P. 1916. Life History and FeedingRecords of a Series of California Coccinellidae.Univ. of Calif. Pub. Tech. Buls. Vol. 1No. 6:251-299.19Journal of the Arkansas Academy of Science, Vol. 9 [1956], Art. 5Published by Arkansas Academy of Science, 1956

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Spinach and Aphid Control by Ladybird Beetles

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