New Zealand Journal of Experimental Agriculture ...

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VII. Azinphosmethyl resistance in strains of Typhlodromus pyri from Nelson a

a

D. R. Penman , D. N Ferro & C. H. Wearing a

b

Department of Entomology , Lincoln College , Canterbury , New Zealand

b

Entomology Division , DSIR , P.B., Auckland , New Zealand Published online: 18 Jan 2012.

To cite this article: D. R. Penman , D. N Ferro & C. H. Wearing (1976) VII. Azinphosmethyl resistance in strains of Typhlodromus pyri from Nelson, New Zealand Journal of Experimental Agriculture, 4:4, 377-380, DOI: 10.1080/03015521.1976.10425903 To link to this article: http://dx.doi.org/10.1080/03015521.1976.10425903

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377

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Integrated control of apple pests In New Zealand VII. Azinphosrnethyl resistance in strains of Typhlodromus pyri from Nelson By D. R.

PENMAN AND

D. N

FERRO

Department of Entomology, Lincoln College, Canterbury, New Zealand

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AND

C. H.

WEARING

Entomology Division, DSlR, P.B., Auckland, New Zealand (Received 20 July 1976)

ABSTRACT The mite Typhlodromus pyri Scheuten (Acari: Phytoseiidae) , 11 predator of European red mite Panonychus ulmi (Koch), was detected in 16 of 22 surveyed apple orchards (1975) in Nelson, New Zealand. Azinphosrnethyl had been used extensively on these properties for some years for codling moth and leafroller moth control, and suggestions of field t esistance to azinphosmethyl by T. pyri were confirmed in laboratory tests. Detailed toxicological examination of T. pyri from four properties established LCoo values for three strains considerably higher than previously determined values from Nelson orchards (1971). LCoo values ranged from 0.08% to 0.30% a.i. azinphosmethyl. The LCoo for the Appleby-R strain previously tested in 1971 increased from O.07~o to 0.30% from 1972 to 1976. The slopes of the dosage-mortality lines were similar for all strains. Integrated control of European red mite using T. pyri appears feasible at the detected levels of resistance. LCoo values increased curvilinearly in response to continuing exposure to azinphosmethyl, the most resistant strain having the longest history of exposure to azinphosmethyl, The implications of this relationship for integrated mite control are discussed.

INTRODUCTION Successful integrated control of phytophagous mites in orchards relies mostly on predaceous mites being resistant to commonly used orchard spray materials. Azinphosmethyl has been used in the Nelson region for some years in most spray programmes to control codling moth, Laspeyresia pomonella (L.), and a complex of leafroller species. Resistance to azinphosmethyl in the existing phytoseiid mite populations could therefore be expected to develop. Resistance of predaceous phytoseiid mites to azinphosmethyl has been reported for several Typhlodromus occidentalis Nesbitt species. showed azinphosmethyl resistance in the western U.S. (Croft & Jeppson 1970) and resistance of Amblyseius fallacis (Garman) has been reported by several workers (Motoyama et al. 1970; Rock & Yeargan 1971; Ahlstrom & Rock 1973; Croft & Meyer 1973; Croft et al. 1976). Hoyt (1972) recorded comparatively low levels of resistance in Typhlodromus pyri Scheuten to azinphos-

methyl in Nelson, New Zealand and Watve & Lienk (1975, 1976) have recently found higher levels of resistance to azinphosmethyl to occur in the latter species in New York. Hoyt (1972) considered resistance levels in T. pyri in New Zealand too low to enable the predators to survive repeated applications of azinphosmethyl. After the suggestion of Hoyt (1973) that monitoring of T. pyri populations may indicate major changes in susceptibility of that species to chemicals, a survey was conducted in the Nelson district during January 1975. Sixteen of 22 orchards contained T. pyri (Wearing & Penman 1975). This paper reports on the preliminary assessment in January 1975 of resistance in field-collected T. pyri, and a more detailed toxicological investigation in December 1975 and January 1976 of T. pyri from selected properties.

METHODS Preliminary assessment of resistance 1'. pyri was field-collected in Nelson and whole

N.Z. Journal of Experimental Agriculture 4: 377-80

N.Z.

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JOURNAL OF EXPERIMENTAL AGRICULTURE, VOL.

leaves containing both predators and prey were air-freighted in plastic bags to Lincoln College for testing. Number of live predators recovered varied considerably depending on time in transit and the necessity for storage of some samples before testing. Samples were collected before spray applications so residues would be expected to be minimal. Only vigorous active female T. pyri were selected for testing. However, many T. pyri often died while in transit. Resistance was assessed using the slide-dip technique similar to that described for Tetranychus urticae (Anon. 1968). Resistance was preliminarily assessed at one concentration of azinphosmethyl, viz., 0.07% a.i., which was the LC50 value obtained by Hoyt (1972) for the resistant strain of T. pvri. Percent mortality at that concentration indicated which populations were worthy of further detailed study. Twenty to 30 adult female T. pyri were placed on their backs on double-sided sticky tape attached to a microscope slide. All toxicant solutions were prepared from a 50% wettable powder formulation of azinphosmethyl in distilled water. Slides were dipped for 5 sec and excess liquid was removed from the slides with blotting paper. Control slides were dipped for 5 sec in distilled water. Treated slides were held in an incubator at 27°e and 80 ± 10% RH for 24 h. Mortality was determined by the failure of the mites to move their appendages when touched by a fine brush. Deterrnination of resistance levels Whole-leaf samples containing T. pyri and prey species were recevied at intervals from selected properties in Nelson. Problems with transport occurred, similar to those experienced with the earlier survey samples. Insufficient live predators were available for adequate numbers to be tested from some properties. Dosage-mortality data were obtained by the slide-dip technique. Up to six concentrations of the 50% wettable powder formulation of azinphosmethyl were used plus a distilled water

4, 1976

control. Twenty adult female T. pyri were placed on each microscope slide and, where possible, 80 T. pyri were treated at each dosage level. Treated slides were held at nOe and 80 ± 10% RH for 24 h before determination of mortality. LC;;o values were obtained by plotting dosagemortality data on log-pro bit paper and fitting the lines from probit analysis.

RESULTS Preliminary assessment of resistance Of the 16 orchards where T. pyri was found in the survey, 12 had sufficient predators for a preliminary assessment of resistance to azinphosmethyl. Eleven samples had been exposed to regular azinphosmethyl applications, and one sample was from the DSIR Appleby Research Orchard, which had never been sprayed with azinphosmethyl. At an azinphosmethyl concentration of 0.07% a.i., corrected mortalities in the survey orchards ranged from 9.0% to 45.0% (mean 22.3 %) . The corrected mortality for the susceptible predators (Appleby Research Orchard) was 64.6%. . The comparatively low mortality (22.3%) of T. pyri to azinphosmethyl at the LC50 value determined by Hoyt (1972) suggested that populations of T. pvri existed with a substantially greater level of resistance than previously determined. Determination of LC50 values was confined to four properties where T. pyri occurred in large numbers and was giving some measure of mite control in spite of continued application of azinphosmethyl. Determination of resistance levels The dosage-mortality lines for the four tested strains are shown in Fig. 1. Unfortunately, high transit mortalities in a strain having no history of azinphosrnthyl applications prevented strains being compared with a susceptible strain. Table 1 presents details of the toxicological responses of each strain. Testing the strains at

TABLE 1 - Toxicity of azinphosmethyl to field-collected strains of Typhlodromus pyri Strain

Kilmartin (13):1: Wells (9) Stucke (15) Appleby-R (16) Appleby-R (9)

Date tested

17 20 27 23

Dec Tan Tan Feb

1975 1976 1976 1976 1971

t Expressed as % active ingredient

LC50t

95% conf.

LCD(it

Slope

0.16 0.08 0.25 0.30 0,07

0.12-0.22 0.06-0.10 0.21-0.30 0.19-0.46

1.63 0.93 1.54 5.87

1.63 1.52 2.09 1.25

limits for LC50

t Number of seasons usage of azinphosmethyl including the current season, 1975-76

PENMAN

ct al.:

INTEGRATED CONTROL OF ApPLE PESTS.

Vl I

379

L

AP P,e b Y F rl97S-Gl

Stucke

(1975-6)

/

LC 50

I

50

Wells (1975-6

"Appleby R (19";O-1)

A~.------

~O-lli!!.:1L-__5 O - - - -

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NUM~ER

L ..

10

15

YEAgS EXPOSUR,:: -:0 :\ZINPHOSMETI-l:,'L

Fig. 2 - Relationship betwen LC"o values for field collected strains of T. pyri and the number of year: of exposure to azinphosmethyl The year tested i given in parenthesis. o..-_ .

0"-----

PERCENT

0·8"

- '--'3'0-

al-AZINPHOSMETHYL

Fig. 1 - Dosage-mortality lines for the four strains of Tvphlodromus pyri treated with azinphosmethyl. 'l _ Kilmartin; A _ Wells; II _ Stucke; 0 - ApplebyR.

DISCUSSION

Resistance to azinphosmethyl in T. pyri ir Nelson has apparently become much more wide widespread since the initial survey by Hoy (1972) . Hoyt failed to find resistant strains 01 T. pyri in any orchards other than the Appleby Research Orchard where a strain was found in 1967-68 (Collyer 1976). Azinphosmethyl has different dates may have affected the toxicological remained the dominant chemical in spray proresponses, depending on the selection pressure grammes for control of leafroller species and from azinphosmethyl applied at that point in the codling moth, and the continued pressure had season. However, only the Wells strain with a led to the selection of resistant strains of T. pyri. LC31l value of 0.08% approximated the toxico- A significant proportion of Nelson orchards now logical responses shown by Hoyt (1972) for appears to have T. pyri populations resistant to T. pyri (R. strain LCilO = 0.07%; Slope = 2). azinphosmethyl. The other three strains all had LCilO values Detailed toxicological examination shows the greater than that for the Wells strain. The slope selection for resistance in T. pyri was not comvalues were similar to values obtained by Hoyt plete at the time of testing by Hoyt (1972). (1972) and the slopes of the dosage-mortality T. pyri has increased its resistance; where the lines were similar for all strains tested. The LC95 LC"o of the Appleby-R strain in 1971 was 0.07% values suggest that high concentrations would be it is now 0.3%. necessary for complete mortality of T. pyri. ConThe LC"f) values for the most resistant strains versely, there could still be relatively high closely approximate those detected for othei mortalities at comparatively low concentrations. species of predatory mites in response te The LC~o for the tested strains was highest in azinphosmethyl. A. fallacis had an LC"o value the strains with the longest history of exposure to of 0.43 % in tests conducted by Motoyama et al azinphosmethyl (Table 1). By incorporating the (1970) and T. occidentalis had an 0.203 % LC;;l LC:;o values obtained by Hoyt (1972) for the value (Croft & reppson 1970). Watve & Lienk Appleby-S strain (no azinphosmethyl exposure) (1976) found LC"f) values of resistant strains oi and the Appleby-R strain (9 years' azinphos- T. pyri in New York to range from 0.140% te methyl exposure), and plotting the LC:;o values 0.234%. Successful integrated mite control pro against the number of years exposure to azinphos- grammes have been based on the former twc methyl (Fig. 2), LC:;o values increased in phytoseiid mites. Thus we can assume that proresponse to continuing exposure to azinphos- vided other harmful pesticides are not used, the methyl. All strains have been exposed to full level of resistance found in T. pyri is sufficient tr commercial rates of azinphosmethyl except for provide a basis for integrated control of Europeai i the Appleby-R strain which was treated at the red mite. Recent results with Appleby-R strai: i rate of 0.025% a.i. in the 1974-75 season. confirm this view (E. Collyer pel's. comm.).

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N.Z. JOURNAL OF EXPERIMENTAL AGRICULTURE, VOL. 4, 1976

The reJationship between the LCiJa values and the number of years of exposure to azinphosmethyl has implications for integrated mite control. Hoyt (1973) suggested that the resistance level to azinphosmethyl in T. pyri in Nelson was too low (Appleby-R LCiJa = 0.07%) to permit sufficient predator survival to control mite populations when they have been treated with full commercial rates of azinphosmethyl. Resistance levels have increased after continued exposure to azinphosmethyl and T. pyri is surviving cornmercial rates of azinphosmethyl. Probably orchards will require at least 10 years of azinphosmethyl usage before resistance levels in T. pyri are sufhcient to permit adequate predator survival. Orchardists moving to integrated mite control should select blocks with an extensive history or azinphosmethyl usage before relying on T. pyrt to provide an effective adjunct to mite control by chemicals.

Acknowledgmenls

Miss J. Dunbar, Mrs T. Cowie, Miss A. Greene, and Mr R. B. Chapman for technical assistance in conducting the tests. Mr J. Walker, and other staff of DSIR, Ministry of Agriculture and Fisheries, and the N.Z. Fruitgrowers' Federation for field collections.

REFERENCES Ahlstrom, K. R.; Rock, G. C. 1973 Comparative studies on Neoseiulus fallacis and Metaseiulus occideniaiis for azinphosmethvl toxicity and effects of prey and pollen on growth. Annals of the Entomological Society of America 66: 1109-13. Anon. 1968: First conference on test methods for resistance in insects of agricultural importance. Bulletin of the Entomological Society of America 14: 31-7.

Collyer, E. 1976: Integrated control of apple pests in New Zealand 6. Incidence of European red mite, Panonychus ulmi (Koch) and its predators. N.Z. journal of Zoology 3: 39-50. Croft, B. A.; Jeppson, L. R. 1970: Comparative studies on four strains of Typhlodromus occiII. Laboratory toxicity of ten comdentalis. nounds common to apple pest control. journal of Economic Entomology 63: 1528-31. Croft, B. A.; Meyer, R. H. 1973: Carbamate and organophosphorus resistance patterns in populations of Amblvseius [allacis. Environmental Entomology 2: 691-5. Croft, B. A.; Brown, A. W. A.; Hoying, S. A. 1976: Organophosphorus-resistance and its inheritance in the predaceous mite Amblyseius fallacis. [ournal of Economic Entomology 69: 64-8. Hoyt, S. C. 1972: Resistance to azinphosmethyl of Typhlodrornus pyri (Acarina: Phvtoseiidae) from New Zealand. N.Z. journal of Science 15: 16-21. Hoyt, S. C. 1973: Studies on integrated control of Panonychus ulmi in New Zealand apple orchards. N.Z. journal of Experimental Agriculture 1: 77-80. Motoyama, N.; Rock, G. C.; Dauterman, W. C. 1970: Organophosphorus resistance in an apple orchard population of Typhlodromus (Amblyseius) [allacis. journal of Economic Entomology 63: 1439-42. Rock, G. C.; Yeargan, D. R. 1971: Relative toxicity of pesticides to organophosphorus-resistant orchard populations of Neoseiulus fallacis and its journal of Economic Entomology 64: prey. 350-52. Watve, C. 1'11.; Lienk, S. E. 1975: Responses of two phytoseiid mites to pesticides used in New York apple orchards. Environmental Entomology 4: 797-800. 1976: Toxicity of Carbaryl and siz organophosphorus insecticides to Amblyseius [allacis and Typhlodromus pyri from New York apple orchards. Ibid. 5: 368-70. Wearing, C. H.; Penman, D. R. 1975: Survey for insecticide-resistant predatory mites in Nelson, 1974-75. Orchardist of NiZ, 48: 122.