Timothy J. Kring

EFFECTS OF INSECTICIDES ON ORIUS INSIDIOSUS (HEMIPTERA: ANTHOCORIDAE), MEASURED BY FIELD, GREENHOUSE AND PETRI DISH BIOASSAYS

Abstract Orius insidiosus (Say) is an important predator of several economic pests in cotton. Laboratory-reared males, females and third instar nymphs were exposed to residues of nine insecticides applied to cotton plants in the field, in potted plants in the greenhouse and glass Petri dishes in the laboratory. Insects were exposed for 24-hours and then removed to determine mortality. Insecticides tested were spinosad, indoxacarb, imidacloprid, tebufenozide, methoxyfenozide, abamectin, emamectin benzoate, fipronil and λ-cyhalothrin. Differences were observed in mortality as measured by different methods. Spinosad, imidacloprid and indoxacarb induced significantly higher mortality with treated Petri dishes than on treated cotton plants in the field or greenhouse. No differences in mortality were observed between methods with fipronil or λ-cyhalothrin, and in only one instance with abamectin. Spinosad was not toxic in the field or greenhouse bioassays, but was highly toxic in the Petri dish bioassay. Imidacloprid was moderately toxic in the field and greenhouse, but was highly toxic in the Petri dish bioassay. Indoxacarb had variable toxicity, with low to moderate toxicity in the field and greenhouse, and high toxicity in the Petri dish bioassay. It is apparent that multiple testing methods should be used in evaluating the effects of pesticides on beneficial arthropods.

Suitability of greenbugs, cotton aphids, and Heliothis virescens eggs for development and reproduction of Orius insidiosus

Development, fecundity, and longevity of the predator, Orius insidiosus (Say) (Heteroptera: Anthocoridae), when reared on greenbug [Schizaphis graminum (Rondani)], cotton aphid (Aphis gossypii Glover), or eggs of tobacco budworm [Heliothis virescens (F.)] with green beans or water were examined. Developmental time was shortest when predators were reared on H. virescens eggs and beans and longest when reared on cotton aphids and water. Predators were most fecund when fed H. virescens eggs. The inclusion of beans in the nymphal diet further enhanced fecundity when fed eggs. Longevity of both females and males was significantly shorter when reared on aphids than on eggs. Beans in the nymphal diet enhanced longevity of female predators only in combination with budworm eggs. Female O. insidiosus were largest when reared on H. virescens eggs. Addition of green beans in aphid treatments resulted in increased size of O. insidiosus when compared to aphids and free water.

Seasonal Distribution and Overwintering of Orius insidiosus (Say) in Arkansas

The overwintering and seasonal habitats of Orius insidiosus (Say), timing of diapause in field populations, and seasonal population dynamics in selected crop and non-crop habitats were evaluated during 1992 and 1993 at two locations, one on southwestern and the other in central Arkansas. Each location consisted of three square miles (≈ 7.77 km2) of various habitats. Diapause status was determined by dissection. In early spring, females were found primarily on hairy vetch, crimson clover, and hairy buttercup. During that time, these weeds were flowering and were infested with high populations of thrips. During late spring and summer, populations of O. insidiosus increased in association with increasing thrips populations and flowering of corn, grain sorghum, cotton, and soybean. In the fall, population densities declined sharply and became widely dispersed. In the winter, females collected from both locations were in reproductive diapause from early November until mid-March. No males were recovered during ...

Experimental Treatment Threshold for the Cotton Aphid (Homoptera: Aphididae) Using Natural Enemies in Arkansas Cotton

The potential of an experimental threshold for reducing the number of insecticide applications for control of the cotton aphid, Aphis gossypii Glover, was demonstrated in cotton. A 3-yr field study...

Photoperiodic Sensitivity and Diapause in the Predator Orius insidiosus (Heteroptera: Anthocoridae)

Abstract Ontogenetic timing of photoperiodic sensitivity is critical in the life history of insects that rely on photoperiod as a token stimulus. The life stages of Orius insidiosus (Say) sensitive to photoperiod for diapause induction were investigated by transferring predators between short (10:14 [L:D] h) and long (14:10[L:D] h) constant photoperiods (at 20°C) at various life stages. Bugs were considered to be in diapause if their preoviposition period exceeded 14 d after adult eclosion. The first three instars exhibited no clear sensitivity to photoperiod relative to diapause induction or intensity (as measured by preoviposition period). The fourth instar was somewhat sensitive, appearing to enhance the sensitivity of subsequent stages. In contrast, the fifth instar was highly sensitive to the short photoperiod. Exposure of bugs to short photoperiods during this instar induced diapause in at least 50% of the population. Likewise, the adult stage was sensitive to photoperiod during at least the first 14 d after eclosion. Exposure to short photoperiods during the early adult stage also appears to be necessary to induce diapause in ≈50% of the population. In addition, short photoperiod served to maintain diapause in adult females. Transferring diapausing adults from short to long photoperiods accelerated diapause termination relative to those remaining in short photoperiod.

Rise and Fall of Cotton Aphid (Hemiptera: Aphididae) Populations in Southeastern Cotton Production Systems

Abstract The impact of natural enemies on cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), populations in cotton, Gossypium hirsutum L., production systems in the southeastern United States was evaluated over 3 yr in irrigated commercial cotton fields. Fungal epizootics caused by the entomopathogen Neozygites fresenii (Nowakowski) Batko reduced aphid numbers to subthreshold levels in 1999, 2000, and 2001 and occurred consistently in early to mid-July in all 3 yr. Scymnus spp. were the most abundant aphidophagous predators, although other coccinellid species and generalist predators such as spiders, fire ants, heteropterans, and neuropterans also were present. Studies using arthropod exclusion cages demonstrated little impact of predators or parasitoids on aphid populations before fungal epizootics. Arthropod natural enemies were most abundant after epizootics and may have suppressed aphid populations late in the season. Seed cotton yield, and lint quality were not affected by aphicide applications in any year of the study. Implications of these findings for aphid management in the southeastern United States are discussed.

Mortality of Tobacco Budworm Larvae (Lepidoptera: Noctuidae) and Emergence of Cotesia marginiventris (Hymenoptera: Braconidae) Exposed to Bacillus thuringiensis and Thiodicarb Alone and in Combination

Mortality of Heliothis virescens (F.) larvae and emergence of Cotesia marginiventris (Cresson) were evaluated on terminals collected from cotton in fields treated with Bacillus thuringiensis Berliner var. kurstaki and thiodicarb. Tests were conducted using B. thuringiensis and thiodicarb, independently and in combination. Insecticide rates were those recommended for resistance management in Arkansas. Results indicate that neither B. thuringiensis nor thiodicarb, alone or in combination, provided acceptable control of H. virescens larvae (<33%) by day 16. However, thiodicarb and thiodicarb/B. thuringiensis mixtures provided significantly greater control of H. virescens than did B. thuringiensis application alone. In addition, no significant advantage was gained with tank mixtures of B. thuringiensis and thiodicarb as compared to thiodicarb application alone. Parasitization increased early larval mortality (day 2) only in conjunction with the application of B. thuringiensis. Neither insecticide applied inde...

Effects of Various Insecticide Residues in Cotton on Gender and Developmental Stage of the Insidious Flower Bug (Hemiptera: Anthocoridae)

Orius insidiosus (Say) is an important predator of several economic pests in cotton. Laboratory-reared males, females and third-instar nymphs were exposed to field residues of nine insecticides app...

Effect of imidacloprid on wing formation in the cotton aphid (Homoptera: Aphididae)

The cotton aphid, Aphis gossypii Glover, is considered one of the most important pests of many vegetable and field crops (Leclant & Deguine 1994). In 2002, aphids were present in 70% of US cotton fields, infesting 9.4 million acres of cotton (Williams 2003). Imidacloprid is an effective systemic insecticide (Nauen et al. 1998) with a high degree of residual activity against cotton aphids although the compound is slow acting (Boiteau & Osborn 1997). Imidacloprid acts on the nicotinic acetycholine receptor, causing the insect to reduce or stop feeding, and reduces mobility (Gourment et al. 1994; Boiteau & Osborn 1997). As a result of casual observations of an increased proportion of alate aphids in imidaclopridtreated fields compared to untreated fields, laboratory spray tests were conducted on apterous adult aphids to evaluate the extent of wing formation and fecundity in offspring due to exposure to imidacloprid. Increased wing formation due to insecticide treatment has not previously been reported. Probit analysis using five application rates from 0 to 0.05 Lb ai/A imidacloprid (Provado® 1.6F, Bayer Corporation, Kansas City, MO 64120) were used to establish an LC 50 for imidacloprid of 0.122 ppm (0.0125 Lb ai/A). In imidaclopridtreated fields, aphids may not obtain a lethal amount of insecticide because of insufficient dosage, inadequate coverage, or active avoidance of insecticide residues (Kerns & Gaylor 1992). Each treatment was replicated eight times on greenhouse-produced four-leaf stage cotton (Deltapine 51 and Deltapine 428B; Delta and Pine Land Company, Scott, MS 38772). Ten pots (1 plant/pot) were used in each replication. Ten adult apterous cotton aphids were transferred onto each of the four true leaves of each plant with a fine camel hair brush. Treatments were applied to cotton plants in a spray booth (Research Track Sprayer SB6-079, DeViries Manufacturing, Hollandale, MN 56045). The aphids were allowed to settle and recounted to insure all leaves contained 10 aphids prior to treatment. Five plants were randomly selected and sprayed with the LC 50 solution of 0.0125 Lb ai/A imidacloprid and the other five plants were sprayed with water. Following spraying, plants were allowed to dry and placed in a chamber at 20 ± 3°C, (13:11, L:D). Aphids were counted on each of the four leaves/plant 48 h post-treatment to check mortality and to establish the number of surviving adults for fecundity assessment. The 48 h reading was selected based on mortality assessment from probit analysis. Ten days post-treatment, aphids on each leaf were examined and classified as either apterous or alate based on the presence or absence of wings or wing pads. All replicates were sampled using the same protocol with a total of 80 plants sampled (4 leaves/plant; 10 plants/replicate; 8 replicates). Data on wing formation with log 10 transformed means and on fecundity were analyzed by analysis of variance with means separated using PROC GLM, ANOVA, and t-tests (SAS institute 1997, 1999). Two days post-treatment 89.2% (±0.11) of the aphids survived in the control and 51.4% (±0.13) in imidacloprid treatments (±SE). No significant difference occurred among replications. A significant difference (P ≤ 0.0001) in wing formation was observed between treatments (Table 1). Imidacloprid-treated plants had 12.0% (±1.30) alate offspring compared with 2.0% (±0.24) in the control plants. Further, a significant decrease (P ≤ 0.0003) in fecundity of treated aphids occurred with aphids on control plants having 9.2 ± 0.97 offspring per adult and aphids on imidacloprid plants having 4.9 ± 0.50 offspring. Alate aphids can migrate, have a longer developmental time, produce fewer offspring, and have

Mi-1.2, an R gene for aphid resistance in tomato, has direct negative effects on a zoophytophagous biocontrol agent, Orius insidiosus

Summary This paper reports that even specific targeted forms of pest resistance in plants can have non-target effects, and may not always be compatible with biological control for integrated pest management.