Numbers of arthropods drifting in an irrigation canal were recorded at 30-min intervals during and after an upstream application of ULV malathion. Flower-visiting and parasitic Hymenoptera were the first insects to increase; a bimodal drift pattern resulted from an interruption in the spray application. Diptera exhibited a delayed response but the numbers collected, especially Paracantha culta (Wiedemann), suggest high susceptibility. Ants occurred in large numbers over a long period, but mortality was probably low. Miridae and Cicadellidae were probably more susceptible than Orthoptera and adult Odonata but had similar delayed drift patterns. Tetragnathidae were the most, and Thomiscidae the least, susceptible spiders

Pruess, K. P.

Urbauer, Dewey

English

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University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnFaculty Publications: Department of Entomology Entomology, Department of1973Drift of Terrestrial Arthropods in an IrrigationCanal Following a Wide-Area Application of ULVMalathionDewey UrbauerUniversity of Nebraska-LincolnK. P. PruessUniversity of Nebraska-LincolnFollow this and additional works at: http://digitalcommons.unl.edu/entomologyfacpubPart of the Agriculture Commons, and the Entomology CommonsThis Article is brought to you for free and open access by the Entomology, Department of at DigitalCommons@University of Nebraska - Lincoln. It hasbeen accepted for inclusion in Faculty Publications: Department of Entomology by an authorized administrator of DigitalCommons@University ofNebraska - Lincoln.Urbauer, Dewey and Pruess, K. P., "Drift of Terrestrial Arthropods in an Irrigation Canal Following a Wide-Area Application of ULVMalathion" (1973). Faculty Publications: Department of Entomology. 677.http://digitalcommons.unl.edu/entomologyfacpub/677   Published in Journal of Economic Entomology 66:6 (1973), pp. 1267–1268; doi: 10.1093/jee/66.6.1267. Copyright © 1973 Entomological Society of America; published by Oxford University Press. Used by permission. Submitted June 7, 1973; published December 1, 1973.   Drift of Terrestrial Arthropods in an Irrigation Canal Following a Wide-Area Application of ULV Malathion1   Dewey Urbauer and K. P. Pruess  Department of Entomology, University of Nebraska, Lincoln, Nebraska, USA  Abstract Numbers of arthropods drifting in an irrigation canal were recorded at 30-min intervals during and after an upstream application of ULV malathion. Flower-visiting and parasitic Hymenoptera were the first insects to increase; a bimodal drift pattern resulted from an interruption in the spray appli-cation. Diptera exhibited a delayed response but the numbers collected, especially Paracantha culta (Wiedemann), suggest high susceptibility. Ants occurred in large numbers over a long period, but mortality was probably low. Miridae and Cicadellidae were probably more susceptible than Orthop-tera and adult Odonata but had similar delayed drift patterns. Tetragnathidae were the most, and Thomiscidae the least, susceptible spiders.  ULV malathion at 8 fl oz/acre (9.7 oz AI) was applied aerially to a 16-mile2 area in Dawson County, Nebraska, in August, for 3 consecutive years, in an attempt to reduce the popula-tions of the western corn rootworm, Diabrotica virgifera LeConte. The fate of many organ-isms was monitored in corn and alfalfa, the 2 principal crops in the area, but manpower limitations prevented complete monitoring of other habitats. Giles (1970) used surface-drift samples in monitoring a study in Ohio in which mala-thion was applied to a forested watershed. The treated area in Dawson County is traversed by 2 irrigation canals. Numerous arthropods were observed drifting down these canals after the 1968 and 1969 treatments. An experiment was designed to determine the compo-sition of this drift during the 1970 treatment.   U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  2 Methods  A rectangular net 2 ft wide × 1 ft deep, constructed of 18 mesh/in. plastic screen, was used to collect the surface drift. The net was submerged to a depth of 6 in. Samples were taken from a bridge 1 mile downstream from the point where application of the insecticide began on Aug. 10, 1970. Samples, each of 10-min duration, were taken every 30 min, beginning at 2:50 p.m. and continuing until 8:20 p.m. on the day the treatment was applied. Spraying, in a N–S direction, began at 2:00 p.m. and progressed from W to E in the direction of the canal’s flow. The surface current was slightly less than 1 ft/sec which would have permit-ted the 1st affected arthropods to appear in samples ca. 4:20 p.m. Eastward progress in making the malathion application was at a slower rate than the flow of the canal, the sam-ple point itself not being treated until 6 p.m. A 30-min break in the continuity of the treat-ment occurred between 5:00 and 5:30 p.m. ca. 1/4 mile upstream from the sample site.  Results and Discussion  Many species of arthropods appeared in the surface drift but, except for cited examples, there were few individuals of any 1 species. Thus, arthropods were grouped by families or orders as they appeared in similar patterns in the drift. Figure 1 presents the data graph-ically. Flower-visiting bees and wasps, and parasitic Hymenoptera, were among the 1st nu-merous insects to appear in drift. At the time of their 1st appearance, only a small part of the area had been treated and only insects having an immediate loss of coordination could have been involved. The bimodality of abundance in drift is further evidence of an imme-diate response. Bees and wasps decreased in abundance following the interruption in the treatment at 5:00 p.m., increased again after treatment was resumed, and decreased rapidly after the entire area had been treated. The early appearance of ants in the drift indicates that some individuals must have been affected immediately. Numbers gradually increased, and the drift of ants continued long after the entire area had been treated. Considering the abundance of ants and their pres-ence on vegetation overhanging the canal, we are inclined to conclude that mortality was low in spite of the large number collected in drift. The families Dolichopodidae (several species) and Tephritidae (almost entirely Paracan-tha culta [Wiedemann]) accounted for 48% of all the drift of the order Diptera. The prepon-derance of these 2 families suggest they may have been especially susceptible, even though their appearance in the drift was somewhat delayed. The numbers of P. culta seemed large in relation to the low abundance of thistle, its known host, along this canal. The lapse in time to the 1st appearance in drift was even greater for Hemiptera (mostly Miridae) and leafhoppers (Cicadellidae). In alfalfa, the mortality of Miridae exceeded 90%; thus immediacy of response is not related necessarily to mortality. A similar pattern was exhibited by Orthoptera (52% late instar to adult Melanoplus differentialis [Thomas]) and Odonata. Both of the latter groups are known to have survived the treatment in some num-bers.   U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  3   Figure 1. Number of arthropods taken in surface drift after an application of ULV mala-thion, Dawson County, Nebraska, 1970. Vertical dashed line is potential earliest time at which insects affected by treatment could have appeared at sample site; vertical solid line is time at which entire area upstream from sample site had been treated.  The bimodality in drift of Coleoptera seemed due to differences in the susceptibility of various families. Coccinellidae were extremely susceptible in other habitats. Of the total beetle drift before 5:50 p.m., 30% were Coccinellidae, whereas only 4% of the beetle drift after 7:20 p.m. were representatives of that family. Only 14 western corn rootworm adults appeared in the drift, although this was the most common species in corn fields adjacent to the canal, and 95% control was achieved. While the mortality of southern corn rootworm, D. undecimpunctata howardi Barber, was very low in alfalfa, almost as many as (12) were collected in drift. This species, however, was far more abundant on vegetation overhanging the canal, and drift samples seemed highly se-lective for species living in that habitat. Many species abundant in cropland only a few feet removed from the canal, and known to have suffered high mortality, appeared in the drift in only low numbers. U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  4 These evaluations of drift samples are subjective because of a lack of information on the size of the area which contributed to the drift and populations within that area. Yet data from other habitats are useful in interpreting certain groups. The low number of Thomis-cidae taken in drift corresponds with our inability to measure any mortality in alfalfa where these were the most common spiders collected. The much less common Tetragna-thidae, however, suffered ca. 80% mortality in alfalfa and far outnumbered Thomiscidae in drift. The drift pattern of Agelenidae was very similar to that for Tetragnathidae and perhaps also indicates susceptibility. The bimodal drift patterns suggest a 30-min delay between time of potential contact with the insecticide and loss of coordination. The delay was greater for Lycosidae and Salticidae, but no conclusions can be drawn about their sus-ceptibility because of lack of information on their abundance along the canal. Any arthropod increasing in numbers in drift posttreatment (there were low numbers of many groups drifting pretreatment) must have some degree of susceptibility. The value of the method increases in direct proportion to the accuracy with which statements can be made about the abundance of species in the habitat from which the drift samples arise. Such information was not available in the reported study. The data suggest that the drift-ing insects were almost entirely from among those present on the immediate banks of the canal.  Note 1. Contribution no. 372, Department of Entomology, University of Nebraska. Published with approval of the Director as Paper no. 3642 in the Journal Series, Nebraska Agricultural Experi-ment Station, Lincoln. Received for publication June 7, 1973.  Reference Cited  Giles, R. H., Jr. 1970. The ecology of a small forested watershed treated with the insecticide malathion-S35. Wildl. Monogr. 240, 81 p. 

Drift of Terrestrial Arthropods in an Irrigation Canal Following a Wide-Area Application of ULV Malathion

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University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Faculty Publications: Department of Entomology Entomology, Department of
1973
Drift of Terrestrial Arthropods in an Irrigation
Canal Following a Wide-Area Application of ULV
Malathion
Dewey Urbauer
University of Nebraska-Lincoln
K. P. Pruess
University of Nebraska-Lincoln
Follow this and additional works at: http://digitalcommons.unl.edu/entomologyfacpub
Part of the Agriculture Commons, and the Entomology Commons
This Article is brought to you for free and open access by the Entomology, Department of at DigitalCommons@University of Nebraska - Lincoln. It has
been accepted for inclusion in Faculty Publications: Department of Entomology by an authorized administrator of DigitalCommons@University of
Nebraska - Lincoln.
Urbauer, Dewey and Pruess, K. P., "Drift of Terrestrial Arthropods in an Irrigation Canal Following a Wide-Area Application of ULV
Malathion" (1973). Faculty Publications: Department of Entomology. 677.
http://digitalcommons.unl.edu/entomologyfacpub/677
 
 
 
Published in Journal of Economic Entomology 66:6 (1973), pp. 1267–1268; doi: 10.1093/jee/66.6.1267. 
Copyright © 1973 Entomological Society of America; published by Oxford University Press. Used by 
permission. 
Submitted June 7, 1973; published December 1, 1973. 
 
 
Drift of Terrestrial Arthropods in an 
Irrigation Canal Following a Wide-Area 
Application of ULV Malathion1 
 
 
Dewey Urbauer and K. P. Pruess 
 
Department of Entomology, University of Nebraska, Lincoln, Nebraska, USA 
 
Abstract 
Numbers of arthropods drifting in an irrigation canal were recorded at 30-min intervals during and 
after an upstream application of ULV malathion. Flower-visiting and parasitic Hymenoptera were 
the first insects to increase; a bimodal drift pattern resulted from an interruption in the spray appli-
cation. Diptera exhibited a delayed response but the numbers collected, especially Paracantha culta 
(Wiedemann), suggest high susceptibility. Ants occurred in large numbers over a long period, but 
mortality was probably low. Miridae and Cicadellidae were probably more susceptible than Orthop-
tera and adult Odonata but had similar delayed drift patterns. Tetragnathidae were the most, and 
Thomiscidae the least, susceptible spiders. 
 
ULV malathion at 8 fl oz/acre (9.7 oz AI) was applied aerially to a 16-mile2 area in Dawson 
County, Nebraska, in August, for 3 consecutive years, in an attempt to reduce the popula-
tions of the western corn rootworm, Diabrotica virgifera LeConte. The fate of many organ-
isms was monitored in corn and alfalfa, the 2 principal crops in the area, but manpower 
limitations prevented complete monitoring of other habitats. 
Giles (1970) used surface-drift samples in monitoring a study in Ohio in which mala-
thion was applied to a forested watershed. The treated area in Dawson County is traversed 
by 2 irrigation canals. Numerous arthropods were observed drifting down these canals 
after the 1968 and 1969 treatments. An experiment was designed to determine the compo-
sition of this drift during the 1970 treatment. 
  
U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  
2 
Methods 
 
A rectangular net 2 ft wide × 1 ft deep, constructed of 18 mesh/in. plastic screen, was used 
to collect the surface drift. The net was submerged to a depth of 6 in. Samples were taken 
from a bridge 1 mile downstream from the point where application of the insecticide began 
on Aug. 10, 1970. Samples, each of 10-min duration, were taken every 30 min, beginning 
at 2:50 p.m. and continuing until 8:20 p.m. on the day the treatment was applied. Spraying, 
in a N–S direction, began at 2:00 p.m. and progressed from W to E in the direction of the 
canal’s flow. The surface current was slightly less than 1 ft/sec which would have permit-
ted the 1st affected arthropods to appear in samples ca. 4:20 p.m. Eastward progress in 
making the malathion application was at a slower rate than the flow of the canal, the sam-
ple point itself not being treated until 6 p.m. A 30-min break in the continuity of the treat-
ment occurred between 5:00 and 5:30 p.m. ca. 1/4 mile upstream from the sample site. 
 
Results and Discussion 
 
Many species of arthropods appeared in the surface drift but, except for cited examples, 
there were few individuals of any 1 species. Thus, arthropods were grouped by families or 
orders as they appeared in similar patterns in the drift. Figure 1 presents the data graph-
ically. 
Flower-visiting bees and wasps, and parasitic Hymenoptera, were among the 1st nu-
merous insects to appear in drift. At the time of their 1st appearance, only a small part of 
the area had been treated and only insects having an immediate loss of coordination could 
have been involved. The bimodality of abundance in drift is further evidence of an imme-
diate response. Bees and wasps decreased in abundance following the interruption in the 
treatment at 5:00 p.m., increased again after treatment was resumed, and decreased rapidly 
after the entire area had been treated. 
The early appearance of ants in the drift indicates that some individuals must have been 
affected immediately. Numbers gradually increased, and the drift of ants continued long 
after the entire area had been treated. Considering the abundance of ants and their pres-
ence on vegetation overhanging the canal, we are inclined to conclude that mortality was 
low in spite of the large number collected in drift. 
The families Dolichopodidae (several species) and Tephritidae (almost entirely Paracan-
tha culta [Wiedemann]) accounted for 48% of all the drift of the order Diptera. The prepon-
derance of these 2 families suggest they may have been especially susceptible, even though 
their appearance in the drift was somewhat delayed. The numbers of P. culta seemed large 
in relation to the low abundance of thistle, its known host, along this canal. 
The lapse in time to the 1st appearance in drift was even greater for Hemiptera (mostly 
Miridae) and leafhoppers (Cicadellidae). In alfalfa, the mortality of Miridae exceeded 90%; 
thus immediacy of response is not related necessarily to mortality. A similar pattern was 
exhibited by Orthoptera (52% late instar to adult Melanoplus differentialis [Thomas]) and 
Odonata. Both of the latter groups are known to have survived the treatment in some num-
bers. 
  
U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  
3 
 
 
Figure 1. Number of arthropods taken in surface drift after an application of ULV mala-
thion, Dawson County, Nebraska, 1970. Vertical dashed line is potential earliest time at 
which insects affected by treatment could have appeared at sample site; vertical solid line 
is time at which entire area upstream from sample site had been treated. 
 
The bimodality in drift of Coleoptera seemed due to differences in the susceptibility of 
various families. Coccinellidae were extremely susceptible in other habitats. Of the total 
beetle drift before 5:50 p.m., 30% were Coccinellidae, whereas only 4% of the beetle drift 
after 7:20 p.m. were representatives of that family. 
Only 14 western corn rootworm adults appeared in the drift, although this was the most 
common species in corn fields adjacent to the canal, and 95% control was achieved. While 
the mortality of southern corn rootworm, D. undecimpunctata howardi Barber, was very low 
in alfalfa, almost as many as (12) were collected in drift. This species, however, was far 
more abundant on vegetation overhanging the canal, and drift samples seemed highly se-
lective for species living in that habitat. Many species abundant in cropland only a few feet 
removed from the canal, and known to have suffered high mortality, appeared in the drift 
in only low numbers. 
U R B A U E R  A N D  P R U E S S ,  J O U R N A L  O F  E C O N O M I C  E N T O M O L O G Y  6 6  (1 9 7 3 )  
4 
These evaluations of drift samples are subjective because of a lack of information on the 
size of the area which contributed to the drift and populations within that area. Yet data 
from other habitats are useful in interpreting certain groups. The low number of Thomis-
cidae taken in drift corresponds with our inability to measure any mortality in alfalfa 
where these were the most common spiders collected. The much less common Tetragna-
thidae, however, suffered ca. 80% mortality in alfalfa and far outnumbered Thomiscidae 
in drift. The drift pattern of Agelenidae was very similar to that for Tetragnathidae and 
perhaps also indicates susceptibility. The bimodal drift patterns suggest a 30-min delay 
between time of potential contact with the insecticide and loss of coordination. The delay 
was greater for Lycosidae and Salticidae, but no conclusions can be drawn about their sus-
ceptibility because of lack of information on their abundance along the canal. 
Any arthropod increasing in numbers in drift posttreatment (there were low numbers 
of many groups drifting pretreatment) must have some degree of susceptibility. The value 
of the method increases in direct proportion to the accuracy with which statements can be 
made about the abundance of species in the habitat from which the drift samples arise. 
Such information was not available in the reported study. The data suggest that the drift-
ing insects were almost entirely from among those present on the immediate banks of the 
canal. 
 
Note 
1. Contribution no. 372, Department of Entomology, University of Nebraska. Published with 
approval of the Director as Paper no. 3642 in the Journal Series, Nebraska Agricultural Experi-
ment Station, Lincoln. Received for publication June 7, 1973. 
 
Reference Cited 
 
Giles, R. H., Jr. 1970. The ecology of a small forested watershed treated with the insecticide 
malathion-S35. Wildl. Monogr. 240, 81 p. 


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Drift of Terrestrial Arthropods in an Irrigation Canal Following a Wide-Area Application of ULV Malathion

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