Effect of early season insecticide use on predators and outbreaks of spider mites (Acari: Tetranychidae) in cotton

The Australian cotton industry relies almost exclusively on synthetic insecticides for control of early season pests. These insecticides often disrupt predatory insect activity in the field. Potential predators of the twospotted spider mite, Tetranychus urticae Koch, in cotton, identified in field and confirmed in laboratory experiments, included a theridiid spider, a phytoseiid mite, a lacewing larva, predatory thrips, several Coccinellidae and several Hemiptera. These predators were mostly generalists, having previously been reported as predators of aphids or caterpillars of Helicoverpa spp. The effect of insecticides on T. urticae and its predators was evaluated in three field experiments. Cotton was artificially infested with T. urticae then sprayed five times at seven to ten day intervals with either dimethoate (140 g ai/ha), thiodicarb (750 g ai/ha and 187.5 g ai/ha), endosulfan (735 g ai/ha and 367.5 g ai/ha), methomyl (169 g ai/ha) or amitraz (400 g ai/ha). Tetranychus urticae populations reached higher densities in dimethoate, thiodicarb and methomyl treated cotton than in untreated cotton. Population densities of T. urticae in cotton treated with low rates of endosulfan or thiodicarb were similar to controls, while those in cotton treated with amitraz were lower. All insecticides caused significant reductions in at least one predator group. Significant negative relationships were found between early season abundance of predators and the mid-season abundance of T. urticae and positive relationships between predators and the lag-period for T. urticae outbreaks to develop. Predation is implicated as a key factor influencing the early season survival of T. urticae . The implications for developing integrated pest management strategies in cotton are discussed.

[1]  J. W. Smith,et al.  Impact of early season use of selected insecticides on cotton arthropod populations and yield. , 1986 .

[2]  L. Wilson,et al.  Recovery of Cotton Crops after Early Season Damage by Thrips (Thysanoptera) , 1998 .

[3]  N. Aebischer,et al.  The effect of spatial scale of treatment with dimethoate on invertebrate population recovery in winter wheat , 1994 .

[4]  C. Huffaker,et al.  Ecology of tetranychid mites and their natural enemies: A review: I. Tetranychid enemies: Their biological characters and the impact of spray practices , 1970 .

[5]  Al Bishop,et al.  A Record of Beneficial Arthropods and Insect Diseases in Southeast Queensland Cotton , 1977 .

[6]  Neil W. Forrester,et al.  Management of pyrethroid and endosulfan resistance in Helicoverpa armigera (Lepidoptera: Noctuidae) in Australia , 1993 .

[7]  R. Mensah,et al.  Use of Medicago sativa (L.) interplantings/trap crops in the management of the green mirid, Creontiades dilutus (Stal) in commercial cotton in Australia , 1997 .

[8]  B. Bartlett.  Outbreaks of Two-Spotted Spider-Mites and Cotton Aphids Following Pesticide Treatment. I. Pest Stimulation vs. Natural Enemy Destruction as the Cause of Outbreaks , 1968 .

[9]  M. Hoy,et al.  Vineyard and Laboratory Evaluations of Methomyl, Dimethoate, and Permethrin for a Grape Pest Management Program in the San Joaquin Valley of California , 1979 .

[10]  R. Mizell,et al.  Effects of pesticides on pecan aphid predators Chrysoperla rufilabris (Neuroptera : Chrysopidae), Hippodamia convergens, Cycloneda sanguinea (L.)., Olla v-nigrum (Coleoptera : Coccinellidae), and Aphelinus perpallidus (Hymenoptera : Encyrtidae) , 1990 .

[11]  P. Trichilo,et al.  Natural Enemies of Spider Mites (Acari: Tetranychidae) on Cotton: Density Regulation or Casual Association? , 1991 .

[12]  David Dent,et al.  Insect Pest Management , 1991 .

[13]  A. Dippenaar-Schoeman,et al.  The effect of two pesticides on spiders in South African cotton fields. , 1990 .

[14]  G. Walter,et al.  'Phytophagous' thrips are facultative predators of twospotted spider mites (Acari: Tetranychidae) on cotton in Australia , 1996 .

[15]  R. Morton,et al.  Seasonal abundance and distribution of Tetranychus urticae (Acari: Tetranychidae), the two spotted spider mite, on cotton in Australia and implications for management , 1993 .

[16]  Maurice W. Sabelis,et al.  Spider mites: their biology, natural enemies and control: vol. 1A , 1985 .

[17]  P. Jepson.  Pesticides and non-target invertebrates. , 1989 .

[18]  J. Readshaw.  The ecology of Tetranychid mites in Australian orchards. , 1975 .

[19]  R. Mensah.  Local density responses of predatory insects of Helicoverpa spp. to a newly developed food supplement 'Envirofeast' in commercial cotton in Australia , 1997 .

[20]  J. Fitzgerald,et al.  Control of the pear psyllid, Cacopsylla pyricola, in South East England by predators and pesticides , 1989 .

[21]  Lewis J. Wilson,et al.  Spider Mites (Acari: Tetranychidae) Affect Yield and Fiber Quality of Cotton , 1993 .

[22]  J. H. Frank,et al.  Insect Natural Enemies , 1997, Springer Netherlands.

[23]  P. Room.  PARASITES and PREDATORS OF HELIOTHIS SPP. (LEPIDOPTERA: NOCTU1DAE) IN COTTON IN THE NAMOI VALLEY, NEW SOUTH WALES , 1980 .

[24]  L. Wilson.  Habitats of Twospotted Spider Mites (Acari: Tetranychidae) During Winter and Spring in a Cotton–Producing Region of Australia , 1995 .