University of California

The bionomics of Scolothrips sexmaculatus (Pergande) (Thysanoptera: Thripidae), an insect predator of spider mites


Frank E. Gilstrap
Earl R. Oatman

Authors Affiliations

Frank E. Gilstrap was Assistant Professor, Department of Entomology, Texas A&;M University, College Station, Texas; Earl R. Oatman was Professor of Entomology and Entomologist, Division of Biological Control, Department of Entomology, University of California, Riverside.

Publication Information

Hilgardia 44(2):27-59. DOI:10.3733/hilg.v44n02p027. August 1976.

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The biology, temperature response, and prey requirements for Scolothrips sexmaculatus were studied in the laboratory with Tetranychus pacificus as the main prey. At 26.7 C and 50% relative humidity, the mean life cycle was 8.9 (range: 7.6-10.3) days; egg, 7.2 days; 1st-stage larva, 2.8 days; 2nd-stage larva, 2.5 days; prepupa, 1.2 days; and pupa, 2.5 days. Male and female immatures developed in the same length of time, but as larvae, killed significantly different mean numbers of prey eggs, 43.0 and 56.0, respectively.

Eggs of S. sexmaculatus are inserted into leaf tissue. Larval eclosion lasted a mean 7.6 min, and larvae commenced feeding a mean 40.3 min after vacating the chorion. No larval preference or nonpreference was noted for any given prey stage.

Imaginal molts lasted a mean 9.1 min, and the new adult commenced feeding after a mean 92.7 min. For adult females, no preference or nonpreference was noted for any prey developmental stage. Mating was unnecessary to induce oviposition, which usually commenced on the 1st imaginal day. Unmated females produced only male progeny. Thus, S. sexmaculatus is a facultatively arrhenotokous species.

Larval and adult thrips were behaviorally well adapted to preying on tetranychids which produce copious webbing. Thigmotaxes were evident in all instars, and cannibalism did not occur until prey became scarce.

The lower thermal limit for incubation was between 18.3 and 23.9 C; for larval development, 12.8 and 18.3 C; for mating, 12.8 and 18.3 C; and for production of female progeny, 12.8 and 18.3 C.

At 23.9 to 40.6 C, adult female thrips produced more than a mean 200 eggs during their lifetime. During the reproductive period, a mean 6.2 to 7.2 mite eggs were killed for each thrips egg laid. At 29.4 to 40.6 C, female thrips killed more than a mean 1,700 mite eggs during their lifetime.

Longevity of adult females was inversely related to temperature. Production of total progeny was highest at 29.4 C, although the highest percentage of female progeny occurred at 23.9 C.

Life tables were prepared from data collected at four temperatures, and intrinsic rates of natural increase were calculated therefrom. The rm values for S. sexmaculatus were 0.155, 0.232, 0.304, and 0.360 at 23.9, 29.4, 35.0, and 40.6 C, respectively.

Minimums of 20 and 25 prey eggs were required for development of males and females, respectively. Mean developmental periods of both sexes were increased significantly when larvae were provided only two or three mite eggs per day.

First- and 2nd-stage larvae of S. sexmaculatus effectively searched 2.45cm2 and 10.19cm2 per hr, respectively. Densities of one mite egg per 70.52cm2 and 114.59cm2 were required for development of 1st- and 2nd-stage larvae, respectively.

Literature Cited

Andrewartha H. G., Birch L. C. The distribution and abundance of animals. 1954. Chicago: Univ. of Chicago Press. 782p.

Bailey S. F. The six-spotted thrips, Scolothrips sexmaculatus (Perg.). J. Econ. Entomol. 1939. 32:43-7.

Bailey S. F. The thrips of California. Part I: Suborder Terebrantia. Bull. Calif. Ins. Surv. 1957. 4:143-220.

Bartlett B. E., Katz G. Inflated plastic bags as cages for insects on potted plants. J. Econ. Entomol. 1969. 62:524-5.

Beach A. M. Contributions to a knowledge of the thripidae of Iowa. Proc. Iowa Acad. Sci. 1896. 3:214-28.

Birch L. C. The intrinsic rate of natural increase of an insect population. J. Anim. Ecol. 1948. 17:15-26. DOI: 10.2307/1605 [CrossRef]

Bursell E., Eockstein M. Environmental aspects: Temperature. The Physiology of Insecta. 1964. 1:Academic Press. p. 283-361.

Chapman R. F. The Insects: Structure and Function. 1969. New York: American Elsevier Publishing Company, Inc. 819p.

Clark A. M., Rockstein M., Eockstein M. Aging in insects. The Physiology of Insecta. 1964. 1:Academic Press. p. 230-71.

Deevey E. S. Life tables for natural populations of animals. Quart. Rev. Biol. 1947. 22:283-314. DOI: 10.1086/395888 [CrossRef]

Duffy J. C. Transformations of a carabid (Plochionus timidus), and observations on a coccinellid enemy of the red spider. Incl. footnote re-describing Thrips 6-maculata. Acad. Sci. St. Louis, Trans. 1892. 5:533-42.

Fleschner C. A. Studies on searching capacity of the larvae of three predators of the citrus red mite. Hilgardia. 1950. 20:233-65. DOI: 10.3733/hilg.v20n13p233 [CrossRef]

Fleschner C. A. Natural enemies of tetranychid mites on citrus and avocado in southern California. 1958. 4:627-31. Proc. 10th Intern. Congr. Ent. (Montreal) 1956)

Garman P. The European red mite (Paratetranychus pilosus C. and F.) in Connecticut apple orchards. Conn. Agr. Exp. Sta. Bull. 1924. 252:103-25.

Garman P., Townsend J. F. The European red mite and its control. Conn. Agr. Exp. Sta. Bull. 1938. 418:1-34.

Hinds W. E. Monograph of Thysanoptera of North America. Proc. U. S. National Mus. 1902. 26:157-8. DOI: 10.5479/si.00963801.26-1310.79 [CrossRef]

Hood J. D., Herrick G. W. A list of the insects of New York. Thysanoptera. Mem. Cornell Univ. Agr. Exp. Sta. 1926. 101:68

Huffaker C.B., Flaherty D. L. Potential of biological control of two-spotted spider mites on strawberries in California. J. Econ. Entomol. 1966. 59:786-92.

Huffaker C. B., van de Vrie M., McMurtry J. A. The ecology of tetranychid mites and their natural enemies: A review. II. Tetranychid populations and their possible control by predators: An evaluation. Hilgardia. 1970. 40:391-458. DOI: 10.3733/hilg.v40n11p391 [CrossRef]

Laing J. E. Life history and life table of Phytoseiulus persimilis Athias-Henriot. Acarologia. 1968. 10:578-88.

Laing J. E. Life history and life table of Tetranychus urticae Koch. Acarologia. 1969a. 11:33-42.

Laing J. E. The life history and life table of Metaseiulus occidentalis (Nesbitt). Ann. Entomol. Soc. Am. 1969b. 62:978-82.

Lamiman J. F. The Pacific mite, Tetranychus pacificus McGregor in California. J. Econ. Entomol. 1935. 28:900-3.

Leigh T. F. Considerations of distribution, abundance, and control of acarine pests of cotton. Advances in Acarology. 1963. 1: Ithaca, New York: Cornell Univ. Press. p. 14-20.

Lincoln C., Williams F. J., Barnes G. Importance of a thrips in red spider control. J. Econ. Entomol. 1953. 46:899-900.

Lord F. T. The influence of spray programs on the fauna of apple orchards in Nova Scotia. III. Mites and their predators. Can. Entomol. 1949. 81:202-30. DOI: 10.4039/Ent81202-8 [CrossRef]

McBeth C. W., Taylor A. L., Smith A. L. Note on staining nematodes in root tissue. Proc. Helminth. Soc. Wash. 1941. 8:26

McGregor E. A. Red spider control. J. Econ. Entomol. 1914. 7:324-36.

McGregor E. A., McDonough F. L. The red spider on cotton. U. S. Dept. Agr. Bull. 1917. 416:1-72.

McMurtry J. A., Johnson H. G. An ecological study of the spider mite Oligonychus punicae (Hirst) and its natural enemies. Hilgardia. 1966. 37:363-402. DOI: 10.3733/hilg.v37n09p255 [CrossRef]

McMurtry J. A., Huffaker C. B., van de Vrie M. Ecology of tetranychid mites and their natural enemies: A review. I. Tetranychid enemies: Their biological characters and the impact of spray practices. Hilgardia. 1970. 40:331-90. DOI: 10.3733/hilg.v40n11p331 [CrossRef]

Messenger P. S. Use of life tables in a bioclimatic study of an experimental aphid-braconid wasp host-parasite system. Ecology. 1964. 45:119-31. DOI: 10.2307/1937113 [CrossRef]

Michelbacher A. E. Spider mites on walnut in northern California. J. Econ. Entomol. 1959. 45:936-9.

Michelbacher A. E., Middlekauff W. W., Bacon O. G. Mites on melons in northern California. J. Econ. Entomol. 1952. 45:365-70.

Mori H. A review of biology on spider mites and their predators in Japan. Mushi. 1967. 40:47-65.

Muma M. H. Factors contributing to the natural control of citrus insects and mites in Florida. J. Econ. Entomol. 1955. 48:432-8.

Muma M. H. Predators and parasites of citrus mites in Florida. 1958. 4:633-47. Proc. 10th Internat. Congr. Ent. (Montreal) 1956

Newcomer E. J., Yothers M. A. Biology of the European red mite in the Pacific north-west. Bull. U. S. Dept. Agr. 1929. 89:69

Nicholson A. J. The balance of animal populations. J. Anim. Ecol. Sup. 1933. 2:132-78.

Oatman E. R. Integration of Phytoseiulus persimilis with native predators for control of the two-spotted mite on rhubarb. J. Econ. Entomol. 1970. 63:1177-80.

Oatman E. R., McMurtry J. A. Biological control of the two-spotted spider mite on strawberry in southern California. J. Econ. Entomol. 1966. 59:433-9.

Oatman E. R., McMurtry J. A., Shorey H. H., Voth V. Studies on integrating Phytoseiulus persimilis releases, chemical applications, cultural manipulations, and natural predation for control of the two-spotted spider mite on strawberry in southern California. J. Econ. Entomol. 1967. 60:1344-51.

Oatman E. R., Voth V. An ecological study of the two-spotted spider mite on strawberry in southern California. Environ. Entomol. 1972. 1:34-9.

Pergande T. Habits of thrips. Psyche. 1882. 3:381 DOI: 10.1155/1882/97160 [CrossRef]

Platner G. R., Scriven G. T., Braniger C. E. Modification of a compact refrigerator for bio-ecological studies under controlled physical parameters. Environ. Entomol. 1973. 2:1118-20.

Priesner H. Studies on the genus Scolothrips. Bull. Soc. Fouad Ier Entomol. 1950. 34:39-68.

Quayle H. J. Red spiders and mites of citrus trees. Calif. Agr. Exp. Sta. Bull. 1912. 234:484-530. http://www.archive.org/details/redspidersmiteso234quay

Rice R. E., Jones R. A. Experimental miticides on European red and Pacific mites. Calif. Agr. 1972. 26:12-13.

Scriven G. T., McMurtry J. A. Quantitative production and processing of tetranychid mites for large-scale testing or predator production. J. Econ. Entomol. 1971. 64:1255-7.

Sokal R. R., Rohlf F. J. Biometry: The Principles and Practice of Statistics in Biological Research. 1969. San Francisco: W. H. Freeman and Company. 776p.

Stannard L. J. The thrips, or Thysanoptera, of Illinois. Bull. Illinois Nat. Hist. Surv. 1968. 29:215-552.

van den Bosch R., Hagen K. S. Predaceous and parasitic arthropods in California cotton fields. Calif. Agr. Exp. Sta. Bull. 1966. 820:32 http://archive.org/details/predaceousparasi0820vand

van de Vrie M., McMurtry J. A., Huffaker C. B. Ecology of tetranychid mites and their natural enemies: A review. III. Biology, ecology, and pest status, and host-plant relations of tetranychids. Hilgardia. 1972. 41:343-432. DOI: 10.3733/hilg.v41n13p343 [CrossRef]

Watson J. R. Thysanoptera of Florida. Florida Buggist. 1918. 2:67 DOI: 10.2307/3491882 [CrossRef]

Watson J. R. Synopsis and catalog of the Thysanoptera of North America. Fla. Agr. Exp. Sta. Bull. 1923. 168:11 36.

Whitcomb W. H., Bell K. Predaceous insects, spiders, and mites of Arkansas cotton fields. Ark. Agr. Exp. Sta. Bull. 1964. 690:84

Gilstrap F, Oatman E. 1976. The bionomics of Scolothrips sexmaculatus (Pergande) (Thysanoptera: Thripidae), an insect predator of spider mites. Hilgardia 44(2):27-59. DOI:10.3733/hilg.v44n02p027
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