Clip Cages Research Articles

The effect of reducing growth in winter wheat on the population dynamics of the grain aphid Sitobion avenae (F.)

Summary1 The effect of reducing the growth of winter wheat on population size and development of the grain aphid Sitobion avenae was studied.2 Automatic, mobile, crop shading devices, which reduced radiation comparable to levels found on a cloudy day, whilst minimizing other climatic changes, were used to reduce crop growth. Shading was applied between either GS 31 and 39 (1st node detectable → flag leaf ligule just visible) or GS 39 and 55 (flag leaf just visible → 50% of inflorescence emerged).3 Sitobion avenae populations were initiated at GS 55 and highest populations were subsequently observed on plants shaded between GS 31 and 39.4 Individual aphids confined within clip cages were observed to measure development from birth to adult moult, adult lifespan and fecundity. Results indicated that adult lifespan was shortest on plants shaded between GS31 and 39, whilst there were no differences in development time or fecundity.5 Possible explanations for these observations are discussed.

EFFECTS OF FOLIAR HERBIVORY ON MALE AND FEMALE REPRODUCTIVE TRAITS OF WILD RADISH,RAPHANUS RAPHANISTRUM

In this study, we examined how foliar herbivory affected the relative allo- cation to male and female reproductive traits in a hermaphroditic plant. In two experiments, one in the greenhouse and the other in a growth chamber, leaves of full sibling plants of the annual wild radish, Raphanus raphanistrum, received one of four damage treatments to leaves (0, 25% (two types), or 50% leaf area removal). We controlled natural damage by Pieris rapae larvae through the use of clip cages. Measurements of both male and female reproductive characters were made on a series of flowers produced by each plant over its lifetime. We measured pollen production, pollen size, ovule number, ovule size, petal size, nectar production, and sugar content. Effects of herbivory on plant phenology were also assessed. At the end of the experiment, we quantified total flower production, fruit pro- duction, number of seeds and fruit, and seed and vegetative biomass. In general, male reproductive characters were more affected than female characters by herbivory. Leaf herbivory reduced pollen number and pollen size, whereas ovule size and number were not affected. Petal size, which we also classify more as a male trait, decreased with herbivory. Plants were generally able to completely compensate for herbivory in the total number of flowers and fruit they produced; however, fewer fruits were found in the heaviest damage treatment in the growth chamber experiment. We discuss alternative ex- planations for this pattern based on developmental constraints and adaptive responses. In summary, male fitness traits were much more strongly affected by herbivory than were female traits; full compensation in seed production after herbivory may come at the cost of male reproductive success in these hermaphroditic plants.

Differences in Cellular Abnormalities Induced by the Probing Behaviors of Empoasca kraemeri (Homoptera: Cicadellidae) on Tolerant and Susceptible Common Beans

Cellular abnormalities induced by the feeding behavior of Empoasca kraemeri Ross & Moore were studied in 2 tolerant lines ('EMP 84' and 'EMP 392'), an intermediate ('Porrillo sintetico') and a susceptible ('Calima') cultivar of Phaseolus vulgaris L. Groups of two 3- to 4-d-old Female leafhoppers were placed for 3 h in l clip cage per plant, each covering 1cm2 of fully expanded primary laeves, 1 5 dafter planting. Leaf tissues were fixed 48 h after this access period and prepared for light and confocal microscopy. Damage to the leaf lamina in all genotypes included cell emptying and breakage of cell walls, as well as enlarged intercellular spaces in the palisade and spongy parenchyma. In the main vascular bundle, hypertrophied parenchyma cells plus cells with enlarged nuclei and stained nucleoli were observed. In general, cellular damage was less severe in the tolerant lines than in the susceptible genotypes, although more so for EMP 84 than for EMP 392. Morphometry of autofluorescent tracheary elements showed what seems to be a compensatory response to leafhopper attack in the tolerant lines. Although control leaves from tolerant lines had fewer tracheary elements per vascular bundle after leafhopper feeding, EMP 84 had more tracheary elements in damaged tissues. Both tolerant genotypes had tracheary elements with larger internal radii, which increased their estimated relative flow rates. The implications of cellular damage for the onset of hopperburn, in bean as well as other host plants such as alfalfa and potato, and the mechanisms of tolerance are discussed.

Leaf Temperature Effects on Bemisia argentifolii (Homoptera: Aleyrodidae) Oviposition

Little is known about high temperature thresholds for the whitefly Bemisia Little is known about high temperature thresholds for the whitefly Bemisia argentifolii Bellows & Perring, which thrives during the hot summers common to the south-western deserts of the United States. This study addressed 3 questions relating to B. argentifolii thermal responses. (1) What are the maximum, optimum, and minimum leaf temperatures for oviposition rate? (2) Is the optimum temperature for oviposition dependent on temperature effects on insect physiology or on host plant thermal responses? (3) How does B. argentifolii respond to localized temperature gradients across the host plant leaf? Adult B. argentifolii were placed in clip cages that were attached to the abaxial surface of cotton, Gossypium hirsutum L., and cucumber, Cucumis sativus L., leaves. A temperature gradient was created by either heating or cooling one side of the leaf with water-filled copper tubing placed on the adaxial leaf surface. Minimum and optimum leaf temperatures for oviposition were 16 and 31°C, respectively, and were independent of plant species. No thermal maximum was detected because oviposition occurred at the highest leaf temperature (43°C). Even though oviposition occurred at high temperatures, a stronger than expected preference was shown for the cool side of the leaf temperature gradient. This was true even at lower than optimum temperatures. Thus, even though B. argentifolii appeared capable of reproducing at the highest temperatures commonly encountered in the southwest deserts, they preferred cooler microenvironments, even when temperatures were below optimum for oviposition rate. This response may serve to maximize total egg production by increasing adult longevity.

Snowdrop lectin inhibits development and decreases fecundity of the Glasshouse Potato Aphid ( Aulacorthum solani) when administered in vitro and via transgenic plants both in laboratory and glasshouse trials

The effects of snowdrop lectin ( Galanthus nivalis agglutinin, GNA) on the Glasshouse Potato Aphid ( Aulacothum solani) were tested by bioassays where the protein was incorporated into an artificial diet at a single concentration of 0.1% ( w v ). The results showed that the presence of GNA in the diet throughout the insect's life cycle decreased the fecundity of adult aphids, as measured by nymph production, by up to 65%, but normally caused only a marginal decrease (≤ 10%) in aphid survival. The deleterious effect of GNA was significantly reduced if insects were reared on control diet, and transferred to diet containing GNA at maturity. GNA was also shown to affect the development of nymphal aphids by measuring growth using image analysis software. The presence of GNA in the diet decreased the rate of increase in length and width of the aphids by up to 40%, and, in this assay, also caused high levels of mortality. GNA was expressed in potato plants, ( Solanum tuberosum L.) cv. Desirée, after transformation with a construct containing a gene encoding the protein driven by the CaMV 35S promoter. GNA expression levels in transgenic potato leaves were found to be in the range 0.3–0.4% of total soluble protein, as measured by immunodot blot analysis using polyclonal antibodies raised against the protein. Bioassays carried out under controlled environmental conditions, using clip cages, showed that the number of nymphs produced on these transgenic plants was significantly ( P < 0.01) reduced compared to that on non-transgenic control plants. The decrease in fecundity observed in this bioassay was similar to that seen in the artificial diet bioassays. Large scale glasshouse trials showed that the rate of population build-up on the GNA-expressing plants was approximately four-fold lower than on the control plants. These experiments demonstrate that the insecticidal effects of GNA observed in artificial diets can be reproduced in planta, both under laboratory bioassay conditions and in the glasshouse.

Reduction in Damage to Cotton Plants by a Recombinant Baculovirus That Knocks Moribund Larvae of Heliothis virescens Off the Plant

Genetically engineered viral insecticides have considerable potential as biological control agents. Through genetic manipulation, the wild-type baculovirus Autographa californica nuclear polyhedrosis virus (WT AcNPV) has been modified to encode for an insect-selective toxin derived from the venom of the scorpion Androctonus australis to produce the recombinant virus AcAaIT. Larvae of tobacco budworm ( Heliothis virescens ) infected with the baculovirus AcAaIT fell off the plant 5-11 h before death and were unable to climb back on the plant to continue feeding. These larvae were capable of feeding if placed oil diet or confined to a leaf with a clip cage. Larvae infected with WT AcNPV died on the plant. Larvae infected with AcAaIT consumed significantly less foliage than larvae infected with WT AcNPV or uninfected controls. Thus, because larvae infected with the recombinant AcAaIT fall off the plant prior to cessation of feeding, there is a greater reduction in feeding damage than expected from lethal times. In addition, because AcAaIT causes a knock-off effect, the absence of liquefied cadavers on plants following treatment with AcAaIT may be more desirable to growers and consumers relative to treatment with wild-type virus. The relevance of our results to field use of recombinant viruses in pest control is discussed.

A System of Caging Thrips palmi for Laboratory Bioassay of Pathogens

Thrips palmi Karny (Thysanoptera: Thripidae) is an Asian species considered native to the Malaysian-Indonesian region. It is now found throughout Asia, Africa, Central and South America and the Caribbean. T. palmi has been present in the Caribbean since 1985 (Anonymous 1989) and is a serious threat to vegetable production in the region. It attacks over fifty plant species including eggplant, sweet peppers, cucumbers, melons, pumpkin, squash and beans as well as other commercially important crops (Wang & Chu 1986). Reports from Puerto Rico, Guadeloupe and Trinidad and Tobago indicate that T. palmi caused losses ranging from 50-90% in vegetable plantings (Franqui et al. 1991, Etienne and van Watermuelen 1991, Jones 1990). Chemical control of T. palmi has not been successful due to resistance to a range of insecticides (Guyot 1988, Jones 1990). Consequently, we are currently evaluating pathogens for the control of T. palmi. So far, a new species of Hirsutella Patouillard has been discovered attacking T. palmi in Trinidad (Hall, 1992) and other fungi such as Verticillium lecanii (Zimm.) Viegas and Beauveria bassiana (Bals.) Vuill. cause disease in related Thrips species (Binns et al. 1982, Gillespie. 1986). In order to simply, reliably and accurately bioassay the abilities of such pathogens to infect T. palmi, a new caging system has been developed and is described in this note. In order that a caging system for pathogen bioassay be of value, the following criteria must be met: (i) the insects must be individually contained to eliminate the risk of cross-contamination; (ii) the insect should be able to move freely within the chamber; (iii) the system should permit clear observation of the insects at all times; (iv) there should be sufficient air exchange to supply the needs of the insect and leaf tissue and to prevent condensation (in which small insects such as thrips may drown) on the walls of the chamber or on the leaf discs; (v) the substrate, normally leaf tissue, must be maintained in a palatable form for the duration of the bioassay; (vi) there should be minimal handling of the insect; (vii) the control mortality must be within acceptable limits (below 10%); (viii) the cages must be escape-proof and; (ix) the system must be reasonably simple to set up so that large numbers of assays may be performed without undue difficulty. Meeting these criteria is especially important when working with a small, highly mobile insect such as T. palmi. There is a variety of caging systems for thrips. Most of these have been developed to assay insecticides, to study life-cycles or rear thrips. These range from group rearing on whole leaves in mesh and plastic clip or sandwich cages to individual rearing in glass vials such as the Plaster of Paris block cage (Lewis 1973). The latter cage contains pieces of leaf or grass spikelets kept in glass tubes with one end embedded vertically in plaster and the other plugged with cotton wool wrapped in gauze to prevent the thrips from becoming entangled in the fibres. This is an excellent technique, as are those described by Morse et al. (1986) and Teulon (1992) but all these methods have some disadvantages such as becoming unwieldy when dealing with large numbers of

Survival, Development, and Reproduction of Turnip Aphids (Homoptera: Aphididae) on Oilseed Brassica

Fecundity, survival rate, and days to maturity of turnip aphids, Lipaphis erysimi (Kaltenbach), were studied on 10 accessions of Brassica spp. that had only moderate damage ratings when compared with ‘Toria-A’ ( Brassica campestris L. cultivar) and K-841 ( Eruca sativa Miller breeding line). Clip cages confined the developing nymphs and reproducing adults on the leaves of these oilseed accessions. Fecundity of turnip aphids was significantly lower on UCD-310/3 and K-841. Survival of nymphs was significantly lower on UCD-12/4, UCD-6/13, and K-841. Turnip aphids took fewer days to mature on ‘Toria-A’ than on UCD-31O/3, K-841, UCD-6/24, and UCD-1214. The rm value for turnip aphids was significantly higher on ‘Toria-A’ than on all other accessions, whereas it was lowest on UCD-310/3 and K-841. In an experiment to determine the predictive value of r m estimates among moderately resistant accessions, we determined the increase in aphid numbers caged for 10 d after infestation of two 6-leaf plants per pot with 10 aphids per plant. Aphid counts were significantly higher on ‘Toria-A’ compared with UCD-13/l, UCD-310/3, and K-841; UCD-13/l had significantly higher aphid counts than UCD-310/3, and K-841. When limited by host plant quality (damage), turnip aphid numbers on ‘Toria-A’ peaked on the 12th d; on UCD-13/1 and UCD-310/3 they peaked on the 18th d; and on K-841 on the 26th d after infestation. Overall, UCD-310/3 had the best antibiosis to L. erysimi of the accessions evaluated.

Estimation of Life Parameters of Monelliopsis pecanis , Monellia caryella , and Melanocallis caryaefoliae (Homoptera: Aphididae) on Single Pecan Leaflets

Population parameters (mean generation time, intrinsic and finite rates of increase, and days for population to double) and the components of the intrinsic rate of increase (developmental and prereproductive times, total fecundity, percent immature mortality, and fecundity rate) were estimated for Monelliopsis pecanis , Monellia caryella , Melanocallis caryaefoliae in clip cages placed on pecan, Carya illioensis (Wang.) K. Koch, leaflets exposed to ambient environmental conditions in an orchard from mid-June to late October. Developmental and prereproductive times differed between species and decreased over time during the growing season. Females produced less progeny when their offspring remained in cluster in the cages for 4–6 d than when offspring were removed daily after counting. Mortality was not a factor in determining the rate of increase because of low mortality of nymphs during the reproductive periods. M. caryella had the shortest developmental, prereproductive, and generation times and required less time for its population to double, yet M. caryella had the highest mean total fecundity, fecundity rate, and intrinsic and finite rates of increase. Results are compared with studies from the literature done at constant temperatures.

Effect of cassava variety on the biology of Bemisia afer (Priesner &amp; Hosny) (Hemiptera: Aleyrodidae)

The biology of Bemisia afer (Prisner & Hosny) reared in clip cages on leaves of 15 varieties of cassava, Manihotesculenta (Crantz)(Euphorbiaceae) was studied under field conditions during the cold months of June—August and during the warm months of September—October. Both variety and time of the year significantly affected the developmental period, the rate of population increase and the mortality. The longest mean developmental period (59.5 days) occurred on the MH108 leaves during the cold months (at 20°C and 62.9% r.h.), while the shortest (27.1 days) was on the Kithekere variety during the warm months (at 25°C and 53% r.h.). The pest population increased most rapidly on MH84 (at 5.4 eggs per female per day) and slowest on the Nigerian 3057/1 (at 0.9 eggs per female per day). The mortality of the pest indicated that Chitembwere had the greatest killing power (K = 2.555) and Nigerian 3057/1 had the least (K = 0.0760). The combined use of the developmental periods, rate of population Increase and mortality indicated that Gomani was the most resistant while Kithekere was the least resistant variety to B. afer. Other varieties with high resistance properties included MH108, Chitembwere and Mbundumali. Of the three biological characteristics used, the developmental period was the most powerful while the rate of population increase was the least. Pubescence of a cassava variety was only weakly associated with resistance to B. afer (r = 0.48) suggesting that other factors are more responsible for resistance to this pest than hairiness.

Evaluation of screening methods and search for resistance in muskmelon, Cucumis melo L., to the twospotted spider mite, Tetranychus urticae Koch

Three techniques of screening for resistance in muskmelon, Cucumis melo L., to the twospotted spider mite, Tetranychus urticae Koch, were compared in a laboratory test. Coefficient of variation values were approximately equal for a whole-leaf and floating-disc technique in terms of mean number of mobile mites and eggs, whereas both were substantially lower than that associated with a clip cage. Therefore, both the floating-disc and whole-leaf technique are indicated as superior techniques for isolating mites on melon leaves in screening trials. In greenhouse mass screening trials (using a whole-leaf technique), many lines exhibited lower densities of adult twospotted spider mites compared with a standard commercial variety ‘Perlita’. Melon lines ‘BUS’, ‘CHI’, Plant Introduction (PI) 164343 and PI 17895 exhibited resistance in greenhouse mass screenings and had significantly lower numbers of female mites per leaf in more intensive greenhouse screenings. PI lines 124101, 124431, 125896 and 125956, which expressed resistance in greenhouse mass screenings, also had low densities of mites in field screening.

Control of the Sweetpotato Whitefly on Poinsettia Under Laboratory Conditions, Summer 1989

Abstract Poinsettias (‘Annette Hegg, Brilliant Diamond’) were obtained as rooted cuttings, potted in 15 cm pots in a greenhouse at the UCR and allowed 4 wk growth before use. Twenty sweetpotato whiteflies were confined to 2 fully expanded leaves/plant on 25 plants for a 24 h period by clip cages. To obtain both eggs and nymphs for testing, plant exposures to whiteflies were made to one set of plants on 25 May and to another on 1 Jun. Numbers of eggs and nymphs were counted 10 d after the earlier exposure. Leaves were assigned to treatments at this time. Leaves were then dipped for 10 s into treatments prepared in quart glass jars. Treated plants were held on raised benches in the greenhouse at 26.7°C for the remainder of the trial. Post-treatment counts of nymphs and eggs were made 4 and 12 DAT respectively.

Genetic improvement of a parasitoid: Response ofTrioxys pallidusto laboratory selection with azinphosmethyl

Colonies of Trioxys pallidus Haliday (Hymenoptera: Aphidiidae) were collected from California walnut orchards during 1985–86 and screened for variability of responses to azinphosmethyl. Variability was found and laboratory selection was initiated with four colonies. All colonies responded to selection; after seven to 12 selections, three colonies were combined (Select colony) and selection was conducted an additional 27 times. The corresponding base colonies were also combined and maintained for comparisons (Base). Concentration/mortality lines obtained for the Select and Base colonies after five and 27 selections indicated seven‐ and 9.2‐fold differences in LC50 values respectively. Survival of the resistant strain varied with bioassay method and decreased in the order: clip cages on treated foliage > treated plastic cups with untreated mesh tops > treated plastic cups with treated mesh tops> treated cups with treated solid lids. The initial bioassay results with treated plastic cups suggested that the s...

Time Response to Direct Vs. Indirect Exposure to Aphicides, 1990

Abstract A colony of the cotton aphid was established from aphids collected at Stoneville, MS, and was bioassayed after 3 mo in culture. Individual greenhouse-grown cotton leaves (DES-119, nontreated seed) were sprayed with formulated insecticides at recommended field rates using a laboratory spray chamber calibrated to deliver 6 gal/acre at 30 psi with a TX6 cone nozzle moving at 2 mph. Each leaf was sprayed either on the top surface or on the underside of the leaf and allowed to' dry. Controls consisted of leaves sprayed with water only. Aphids were then caged in ventillated clip cages on the underside only of leaves, so that aphids recieved either indirect or direct exposure to insecticides, depending on which side of the leaf was sprayed. Cumulative mortality was determined for 24 and 48 h of exposure, during which time treated leaves and aphids were held in a laboratory chamber at 80°F, 14:10 L:D and 50% RH. For each insecticide tested, 6 leaves (replications) were treated and 10 adult female aphids were caged on each leaf. Statistical comparisons were made for percent mortality within a chemical treatment for time and method of exposure. All tests were not conducted on the same day, so statistical comparisons were not made among chemicals.

Resistance in groundnut (Arachis hypogaea L.) to Aphis craccivora (Koch).

SUMMARYThe behaviour, development and reproductive capacity of Aphis craccivora, vector of a number of groundnut viruses, are compared on a range of susceptible and resistant genotypes. Field trials demonstrated no significant difference between genotypes in the rate of arrival of alates, but population development was slower, and subsequent population decline faster, on the genotype EC 36892 (ICG 5240). Behavioural studies in the screenhouse, likewise showed no inhibition to alighting onto EC 36892 though choice tests demonstrated a significant redistribution of the population in favour of the susceptible genotype TMV 2 (ICG 221) over the following 10 h. In clip cage experiments, development was faster and nymphal numbers were higher on the genotype TMV 2 compared to EC 36892.

Field resistance in three bread wheat lines to the Russian wheat aphid, Diuraphis noxia (Hemiptera: Aphididae)

The levels of resistance in three bread wheat lines, SA 2199, SA 1684 and SA 463, to field infestations of Diuraphis noxia were studied in 1986 and 1988 in comparison with susceptible lines. Counts were made of the number of infested plants, number of infested shoots and number of aphids per infested shoot. In 1988, nymphal production of individual aphids in clip cages was also determined. Lower infestation levels were measured on the resistant lines, with the greatest difference found in the number of aphids per infested shoot, which varied from 2.8 on a resistant line to 141.8 on a susceptible cultivar in 1986. In 1988, numbers varied from as low as 0.9 on a resistant line to as high as 79.1 on a susceptible cultivar. Significantly fewer nymphs per adult per day were produced in clip cages on the resistant lines than on the susceptible cultivars. Feeding symptoms on the leaves of resistant plants were restricted to chlorotic spots and no leaf rolling occurred, as in the case of susceptible plants.

Control of Whiteflies on Poinsettia Under Glasshouse Conditions, Summer 1988

Abstract Poinsettias (Annette Hegg cv. Brilliant Diamond') were obtained as rooted cuttings and potted in 6 inch pots in a greenhouse and allowed to grow for 4 wk before use. Twenty sweet potato whiteflies or greenhouse whiteflies were confined to 4 expanded leaves/plant for a 24 h period by clip cages, 2 separate times, a wk apart. Each plant contained one whitefly species and one treatment and there were 4 plants/treatment. Half of the plants were exposed at each time period. One day after the second exposure the number of immatures were counted on the oldest exposure and the number of eggs on the more recent exposure. Plants were separated into treatment groups followed by treatment using a 2 gal hand sprayer at 45 psi. Treated and water treated (control) plants were kept in the greenhouse at 80°F and ambient relative humidity for 4-5 d. Post-treatment counts were taken 4 d later on treated immatures and 10 d later on eggs.

Control of the Sweet Potato Whitefly on Poinsettia Under Glasshouse Conditions, 1989

Abstract Poinsettias (Annette Hegg cv. Brilliant Diamond) were obtained as rooted cuttings and potted in 6 inch pots in a greenhouse at UCR and allowed 4 wk growth before use. At such time, 10 whiteflies were confined to 2 expanded leaves/plant for a 24 h period by clip cages. Eight to 12 d later the number of immatures were counted and plants were separated into groups of 4 (3 plants with first and second instars and one plant with third, fourth and pupal stages). Plants were then treated with 7 treatments and a water control using a 2 gal hand sprayer at 45 psi. Treated plants were kept in a greenhouse at 80°F and ambient relative humidity for 4-5 d. Post-treatment counts were taken 4 d later when mortality was obvious.

Control of the Sweet Potato Whitefly on Poinsettia Under Glasshouse Conditions, Fall 1988

Abstract Poinsettias (Annette Hegg cv. 'Brilliant Diamond) were obtained as rooted cuttings and potted in 6 inch pots in a greenhouse and allowed 4 wk growth before use. At such time, 10 whiteflies were confined to one expanded leaf on each of 60 plants for a 48 h period by clip cages. Ten days later the number of immature (first and second instar) sweetpotato whitefly were counted. Ten plants were assigned to treatments in a randomized block design and treated on 10 Oct with 5 treatments and a water control using a 2 gal hand sprayer at 45 psi. Treated plants were kept in a greenhouse at 80°F, 14:10 LD photoperiod, and ambient relative humidity for the remainder of the trial. A second pre-treatment count was made on day 7 (17 Oct) prior to treating 5 of the 10 plants a second time. Posttreatment counts of emerged whiteflies were taken 14 d later when adults were sure to have emerged. No apparent phytotoxicity appeared on any treatment nor were there significant differences between treatments and control after 7 days. Therefore, percent emergence was calculated using number emerged per replicate divided by the number of live immatures from this 7 day count. Results indicate that Enstar performed best.

Screening of Aphis Gossypii for Insecticide Tolerance, 1989

Abstract Colonies of A. gossypii were assayed for insecticide tolerance using a leaf-dip test. Two colonies represented collections made from areas of control failures in Stoneville, MS, and Lawrence County, AL, and were reared in the greenhouse on DES 119 cotton 3 mon before a susceptible colony was established from aphids collected from Earlimart, CA. Cotton terminals were swirled 15 sec in water (control) or in a solution of formulated insecticide at a concentration causing approximately 90% mortality of susceptible insects: Lorsban 300 ppm, Thiodan 300 ppm, Capture 10 ppm, Metasystox-R 100 ppm, and Bidrin 100 ppm. Terminals were allowed to dry 45 min, placed in water wicks, and infested on leaf undersides using ventilated clip cages. Infested terminals were held at 80° F, 50% RH, and 14:10 L:D. Four replications (1 replication = 1 terminal) of 10 wingless adults/replication of similar size and color (green/black) from each colony were run. Mortality was determined 24 h later. Additionally, Lorsban and Thiodan were assayed using a laboratory spray table at field rates (1.0 lb and 0.33 lb (AI)/acre, respectively), calibrated to deliver 6 gal/acre (30 psi, TX 6 nozzle, 2 mph). Six replications of 10 aphids/replication were run for each treatment; caging, holding conditions, and test duration were the same as for dip bioassays.