Field Cage Studies Research Articles

Evaluation ofStethorus nigripes [Col.: Coccinellidae] for biological control of spider mites in California almond orchards

Stethorus nigripes Kapur (=S. loxtoni Britton & Lee) was imported from Australia in 1978 and released in California during 1978–1980. Laboratory and field cage studies evaluated aspects ofS. nigripes' biology considered likely to affect establishment. Our tests indicated that most ♀♀ became nonreproductive during late fall. The females' reproductive arrest seems not to be a true diapause, but may be due to chill experienced by pupae. Survival over winter of both sexes was low if they were not provided abundant prey; honey or water alone were inadequate.S. nigripes adults and larvae could not feed onPanonychus ulmi (Koch) orP. citri (McGregor) eggs and avoided all stadia ofBryobia rubrioculus (Scheuten) in laboratory tests, so it is not a “generalist” predator of spider mites.S. nigripes also is susceptible to pesticides used to control key insect pests in almonds, including the pyrethroid, permethrin (LC 50 value=0.48 g A.I./100 liter water). Releases to establish this predator were discontinued after 3 years, asS. nigripes' sensitivity to pesticides and its requirement for prey during winter seem sufficient to account for its failure to establish. Even if established, these factors might preventS. nigripes from becoming an effective spider mite predator in pesticide-treated almond orchards in California.

Comparative Damage and Leaf Area Consumption By the Tobacco Budworm and Corn Earworm on Maryland Tobacco12

Field and field cage studies were conducted in 1978 to compare larval injury of the tobacco budworm, Heliothis virescens (F.), and corn earworm, H. zea (Boddie), to Maryland variety 609 tobacco plants. Results of the field study showed that for both species, nearly 100% of all damage (defoliation and topping damage) was attributed to the 4th and 5th instars. Of the total number of leaves lost via defoliation, 66.56 and 91.88% were caused by 5th-instar budworm and earworm, respectively. Loss assessment was measured two ways, i.e., actual leaf loss (LLa) (area of damaged leaf vs. predicted whole leaf area) and observed defoliation (Dab) (leaf loss vs. remaining leaf area), and measurements indicated that plants compensated for leaf loss by increasing the laminal area of damaged leaves. Results from the field cage study showed that no significant differences existed between species for many damage parameters. However, the budworm significantly damaged more leaves ( P < 0.029), consumed more foliage ( P < 0.05), and was responsible for a greater loss in leaf guality than the earworm. The results suggest that in formulating management decisions, population estimates should be confined to the last two instars of both species.

Use of a Predator, Podisus maculiventris, to Distribute Virus and Initiate Epizootics12

Laboratory and field cage studies established that surface-contaminated Podisus Maculiventris (Say) can effectively transmit a Trichoplusia ni single-embedded nuclear polyhedrosis virus to plant surfaces for at least 1 week and thus initiate disease in the cabbage looper, T. ni (Hubner). Leaf discs sequentially exposed for 24-h intervals to virus-contaiminated P. maculiventris were bioassayed with cabbage looper larvae to determine presence of virus, and the resulting mortalities were: day 1, 100%; day 3,96%; day 5, 80%; day 8, 65%; day 11, 50%; and day 14, 19%. Virus-contaminated P. maculiventris were released in field cages containing populations of cabbage loopers; virus infections of the looper populations were initiated, and within 3 to 4 weeks, epizootics gave a high level of population suppression.

Releases of Brachymeria lasus1 and Coccygomimus disparis,2 Two Exotic Gypsy Moth3 Parasitoids, in Connecticut: Habitat Preference and Overwintering Potential

Brachymeria lasus (Walker) (Hymenoptera: Chalcididae) and Coccygomimus disparis (Viereck) (Hymenoptera: Ichneumonidae), two exotic pupal parasitoids of the gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), from Japan, were released in northeastern Connecticut in 1979 and in southwestern Connecticut in 1980. B. lasus, like the already established parasitoid Brachymeria intermedia (Nees), attacked hosts primarily in sunny areas and attacked field gypsy moth pupae to a greater extent than field-exposed, laboratory-reared greater wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae) pupae. C. disparis host attacks were not vertically stratified, but wax moth pupae were preferred over gypsy moth pupae. Laboratory-reared gypsy moth pupae exposed from midsummer to fall were heavily parasitized by B. intermedia but very little by B. lasus, suggesting that the latter dispersed from release sites. Field cage studies demonstrated that C. disparis can successfully overwinter in Connecticut, but no evidence is available that B. lasus can do so. Neither species was recovered from the 1979 release plots when these were resampled in 1980, but recovery attempts are planned for at least 3 years.

Field Cage Tests with Nomuraea rileyi Against Corn Earworm Larvae on Sweet Corn123

Field cage studies to determine effects of Nomuraea rileyi (Farl.) Samson on Heliothis zea (Boddie) larvae were conducted in 1975 and 1976. In all infectivity tests, 1st instar mortality was significantly lower than in subsequent instars. Mortality among 4th instars was 95% in early summer 1976, and among 5th instars, 88 and 65% in mid-, and late summer, respectively. In tests to determine effect of number of applications on level of control, the highest mortality of 76% was recorded for larvae sprayed 3 times. All ears in treated and control cages received some degree of damage but damage in all treated cages was significantly lower than in the control.

Field Cage Assessment of the Potential for Establishment of Rogas indiscretus1 Against the Gypsy Moth 23

The value of outdoor field cages in assessing the potential for establishment of exotic parasites of the gypsy moth, Lymantria dispar (L.), is demonstrated, using Rogas indiscretus Reardon as a model. Aspects of its laboratory biology are presented. This Indian parasite was found to produce 3 generations/yr in Connecticut (CT) in gypsy moth larvae artificially supplied as hosts in field cages. It overwintered successfully as a diapausing larva within a mummy and emerged in synchrony with the appearance of young gypsy moth larvae the following spring. Alternate hosts would be needed by this parasite in CT during July and Sept. Based on field cage studies, the availability of suitable alternate hosts at these appropriate periods appears to be the limiting factor for establishment of this parasite in North America.

Field Cage Studies to Detennine Effects of Mexican Bean Beetle Resistance in Soybeans13

The effectiveness of resistance in the soybean cultivar ‘Shore’ in reducing feeding damage and yield looses caused by Epilachna varivestis Mulsant was demonstrated in field cage studies conducted in 1973 and 1974. Caged soybeans were infested artificially at the rates of 1, 2, and 3 adults/row ft. Significant increases in foliar damage and reductions in seed yield were recorded for all 3 infestation rates in the susceptible cultivar ‘York’, as compared to the check plots. Shore suffered little defoliation and no loss in yield except at an infestation rate of 3 adults/row ft, which caused a 17% reduction in yield. Resistance in Shore at the lower infestation rates appeared to come from its ability to prevent or retard larval development which prevented the buildup of high adult numbers.

Forage Losses Caused by the Grasshopper Aulocara elliotti on Shortgrass Rangeland

Highlight: A field-cage study was conducted in 1973 and 1974 to determine the amount of forage (mainly grasses) destroyed by different population densities of the grasshopper Aulocara elliotti. The amount offorage consumed during the third instar and through the adult stage averaged 34.5 mg offorage per grasshopper per day. Thus, an estimated loss of 23.1 lb offorage per acre will resultfrom a density of one Aulocara/m2 if the grasshopper lives for 75 days (45 days as a nymph and 30 days as an adult). Based on total available forage (standing dead and new growth), a 63% forage loss was recorded in 1973 at one site and losses of 26% and 29% at two sites in 1974 resulting from about 20 grasshoppers/iM2. Severe grazing by grasshoppers also resulted in reduced production offorage during the subsequent (1974) season.

Apanteles militaris 1 and Its Host Pseudaletia unipuncta : 2 Biology and Rearing 3 , 4

Apanteles militaris (Walsh), a gregarious braconid parasitoid, attacked 3rd, 4th, and 5th instars of Pseudaletia unipuncta (Haworth) in the laboratory. The mean period from oviposition in the host to emergence was 12.5 days, the pupal stage lasted 6.4 days, and the overall life cycle ranged from 17–30 days and averaged 19 days at 27°C. The mean generation time of P. unipuncta was 35 days; egg, 4 days; larva, 15 days; prepupa, 2 days; pupa, 10 days; and preoviposition, 3–4 days. The cost of mass-rearing the parasitoid and its host was ca. 50/100,000 insects (1971). Parasitoids from the laboratory colony successfully parasitized hosts in field cage studies.

Utilization of Additional Species and Populations of Leafcutter Bees for Alfalfa Pollination

SummaryThe introduction and establishment in the United States of species of Eutricharaea (an Old World subgenus of Megachile) are reviewed. A comparison was made by field-cage studies of American and Spanish populations of M. pacifica and an American population of M. concinna. Significant differences included the following. Spanish pacifica showed the lowest mortality in immature stages (9%). M. concinna built about 4 times as many cells as the other bees, and was the most successful in rearing second-generation adults; seed production was also highest in the M. concinna cages. It is important on economic grounds that the possibilities of rearing other alfalfa pollinators than M. pacifica should be explored further.

Successful Parasitization of Heliothis zea1 and Trichoplusia ni Eggs by Trichogramma23

Laboratory and field cage studies were conducted to determine the degree of successful parasitization by selected Trichogramma stocks for the eggs of Heliothis zea (Boddie), the bollworm, and Trichoplusia ni (Hubner), the cabbage looper. The laboratory studies showed significant increases in female longevity, number of eggs successfully parasitized, and progeny production when H. zea eggs were used as hosts. Two types of field cage experiments were conducted in cotton fields. The 1st type, which had either H. zea or T. ni egg cards in a given field cage, indicated that twice as many H. zea egg cards were found. The 2nd type of experiment had both hosts in varying proportions in each cage, and showed that a higher proportion of H. zea eggs were successfully parasitized even when T. ni eggs were more abundant.

Field-Cage Studies of Native Egg Predators of the Pink Bollworm In Southern California Cotton12

Native egg predators of Pectinophora gossypiella (Saunders) were studied in field cages in cotton during the summer of 1970 in the Coachella Valley, CA. The percent of egg masses attacked, egg consumption within egg masses attacked, and overall egg consumption by the predators were studied for different densities of the same predator species, for different predators at the same density, and for different locations of egg masses on the plants. Chrysopa carnea Stephens, Geocorus pallens Stal, and Nabis americoferus Carayon showed potential as pink bollworm egg predators; Notoxus calcaratus Horn and Spanogonicus albofasciatus (Reuter) showed little promise; and Geocorus punctipes (Say) and Orius tristicolor (White) were intermediate.

Reduction in Effectiveness of Laboratory-Reared Trichogramma12

Field cage studies using cotton plants were conducted to test the hypothesis that laboratory-reared Trichogramma deteriorate in their effectiveness as biological control agents. The results of these studies presented evidence that a deuterotokous Trichogramma stock deteriorated. No reduction in effectiveness could be demonstrated for arrhenotokous stocks. These studies also showed that Trichogramma rapidly lose their effectiveness in field cages and that parasitization of hosts occurs during the day rather than at night.

A field-cage study of feeding behavior of the face fly on dairy cattle.

A field-cage study of feeding behavior of the face fly on dairy cattle.

Field Cage and Laboratory Studies with Bracon kirkpatricki a Parasite of the Pink Bollworm123

A braconid parasite, Bracon kirkpatricki (Wilkinson), was studied in the laboratory to develop mass-rearing procedures, and in field cages to determine the feasibility of using it as a biological control agent against the pink bollworm, Pectonophora gossypiella (Saunders). The total development time on the pink bollworm varied from 22.4±1.2 days at 20°C to 7.9±0.4 days at 35°C. Development was slightly shorter on the beet armyworm, Spodoptera exigua (Hübner), the time decreased from 21.1±1.4 days to 7.6±0.5 days at 20 and 35°C, respectively. The most efficient temperature in terms of development time and successful development was 30°C. Mass-rearing techniques were developed in which the more easily and cheaply produced beet armyworms were utilized as hosts. The results of the field-cage tests showed B. kirkpatricki to be a promising parasite of the pink bollworm early in the season when the pest is concentrated in the blooms. Larvae in bolls were not parasitized.

Hostal Plant Preference for Oviposition by Trichoplusia ni, and Efficiency of Apanteles marginiventris as a Populational Regulator of T. ni in Field-Cage Tests123

Field-cage studies were conducted to determine hostal plant preference for oviposition by the cabbage looper, Trichoplusia ni (Hübner), and its relationship to effectiveness of biological control by Apanteles marginiventris (Cresson). For oviposition, moths preferred collards and cotton to broccoli, cauliflower, or cabbage. When crops were separated into 2 age groups, 21-week-old collards were preferred by T. ni over cauliflower or cabbage, and 15-week-old cotton and collard plants were preferred to broccoli, cabbage, or cauliflower. Significantly more eggs were deposited on 21-week-old broccoli and cauliflower plants than on 15-week-old plants of these species. A. marginiventris did not exhibit a crop preference for oviposition in T. ni. Parasitization by A. marginiventris was very low, which fact suggests that this braconid is an ineffective parasite of T. ni in northern Mississippi.

Field-Cage Assessment of Trichogramma as Parasites of Heliothis zea: Development of Methods1234

Field-cage studies with Trichogramma pretiosum Riley (=T. semifumatum (Perkins)) were initiated to establish a standardized system for future selection of Trichogramma species or races for use in augmentation programs in cotton. Data indicated no preference by parasites for eggs of the bollworm placed on leaves of corn and cotton plants. There was also no preference by the wasps for eggs of H. zea placed on the upper and under surfaces of leaves of the same plants. Parasitization was significantly greater for eggs placed on leaves near the top of the plants than for eggs placed on leaves near the bottom. Eggs were parasitized in significantly greater numbers when placed on white or on green cards with a smooth surface than when placed on black cards with a smooth surface. Hence, future evaluation of Trichogramma stocks will be carried out only by placing host’s eggs on white cards stapled to the under surfaces of leaves near the tops of cotton plants.

The Sterile-Male Technique for Control of Mosquitoes: A Field Cage Study with Anopheles quadrimaculatus

The use of sterile males to control a cage population of a laboratory strain of Anopheles quadrimaculatus was not successful, even though 80 to 90% of the females laid sterile egg clutches. At the ratio of sterile males to normal males being used, complete sterility should have been quickly achieved. Subsequent studies of the survival and sexual vigor of these sterile males indicated that only a small number, about 5%, of the released males were actually competing with normal males for the uninseminated females. Thus, until a more hardy and sexually vigorous male A. quadrimaculatus can be reared in the laboratory, the use of the sterile-male technique to control this insect seems impractical.

Stem treatments to cotton with systemic insecticides against Heliothis zea (Boddie) and H. virescens (F.)

Laboratory and field-cage studies were conducted in Texas in 1965 to evaluate treatments of the systemic insecticides, Azodrin (3-hydroxy-N-methyl-cis-crotonamide dimethyl phosphate), Bidrin (3-hydroxy-N, N dimethyl-cis-crotonamide dimethyl phosphate), American Cyanamid CL-47031 (cyclic ethylene (diethoxy-phosphinyl) dithioimidocarbonate) and Temik (2-methyl-2-(methylthio) propion-aldehyde O-(methylcarbamoyl) oxime), applied incorporated in lanolin to the stems of cotton plants against Heliothis zea (Boddie) and H. virescens (F.). Reductions in numbers of developing larvae of H. zea were substantial on individual plants the stems of which had been treated with Azodrin or CL-47031 and which were artificially infested with eggs. When first-instar larvae of H. zea or H. virescens were caged on plants 3, 7 or 14 days after stem treatment with 2.5, 5.0 or 100 mg. Azodrin, Bidrin or CL-47031 per plant, net mortalities ranged from 21 to 80 per cent after three days. The mortality of adults of H. zea provided with sucrose solutions containing 1 p.p.m. of the systemic insecticides indicated that Azodrin and Bidrin were about equally toxic and much more so than CL-47031 and Temik, and that of adults caged on individual plants in flower that had been treated with Azodrin or CL-47031 suggested that the moths may be killed by the systemic action of these insecticides translocated to the nectar. When adults of H. virescens were released on plants each treated with Azodrin at 25 or 30 mg. in large field cages, reductions in the numbers of eggs deposited, attributed to the effect on the moths of the insecticide in the nectar, and in the numbers of developing larvae, were substantial. Azodrin was the most consistently effective of the four insecticides evaluated.

Effect of 4'-(3,3-Dimethyl-1-triazeno) acetanilide and Other Compounds on Several Lepidopterous Pests of Cotton12

Laboratory applications of 4'-(3,3-dimethyl-l-triazeno) acetanilide (American Cyanamid CL-24055) to cotton plants limited leaf feeding and reduced the larval weights of the bollworm, Heliothis zea (Boddie); tobacco budworm, H. virescens (F.); cabbage looper, Trichoplusia ni (Hubner); yellow woollybear, Diacrisia virginica (F.); and cotton leafworm, Alabama argillacea (Hubner). Feeding damage by the cabbage looper was reduced 90% when larvae were placed on leaves 2 hr after 24 hours. Injection or topical applications of CL-24055 to bollworm larvae did not reduce larval feeding as much as foliage applications. In field-cage studies a 58% reduction occurred in populations of bollworm larvae after treatment with CL-24055. Also, in a field test with CL-24055, a 22% reduction occurred in squares and bolls damaged by Heliothis spp. Tobacco budworm larvae fed leaves treated with CL-24055 weighed less, whether or not the labial palpi were removed. The following materials caused no (A1%) reduction in tobacco budworm and cabbage looper larval feeding and weight: alpha- (3-phenylpropyl) piperonyl alcohol; phenacyl thiocyanate; N-sec- butyl- p -toluamide; p -(1,1,3,3-teracnetgyt-butyl) phenyl propionate; octyl m -toluate;4 (or5)-chloro- N-N -diethy 1-2-methylcyclohexanecarboxamide; N ,2,2-trimethy1-4',5'-(methylenedioxy)-3 (2-methylpropenyl)-2'-propylcyclopropanecarboxanilide; N -butylsuccinimide; 2-methyoxyethyl 4(or 5)-chloro-2-methylcyclohexanecarboxylate; calamus oil distillate fractions; imidazole; and the plant pigment quercetin (3,3', 4'5,7-pentahydroxyffavone).