Showing papers in "Journal of Economic Entomology in 1981"
TL;DR: Although trichlorfon was most toxic to L. acuminata and mexacarbate to P. globosa, the relative LC50s of the six compounds varied at different exposure periods, and a possible explanation on the basis of pharmacological evidences and structure-activity of these compounds has been given.
Abstract: Laboratory studies on toxicity of three carbamate (mexacarbate, carbaryl, and aldicarb) and three organophosphorus (trichlorfon, formothion, and phorate) compounds were made on two species of snails, Lymnaea acuminata Lamarck and Pila globosa Swainson. L. acuminata was more sensitive to the pesticides tested. LC50 values computed for different exposure periods from 24 to 240 h showed a gradual decrease as the exposure time was increased. Although trichlorfon was most toxic to L. acuminata and mexacarbate to P. globosa , the relative LC50s of the six compounds varied at different exposure periods. A possible explanation on the basis of pharmacological evidences and structure-activity of these compounds has been given.
122 citations
TL;DR: This is believed to be the first time that the field effectiveness of a biological control agent has been improved through artificial selection.
Abstract: Laboratory and glasshouse tests were conducted to assess the vigor and reproductive compatibilities of two laboratory-selected carbaryl resistant strains of a predatory mite, Metaseiulus occidentalis (Nesbitt). Traits evaluated included development time, fecundity, sex ratio, mating compatibilities and competition, diapause, persistence of the carbaryl resistance characteristic, and the capability to control spider mite populations under carbaryl sprayed and unsprayed conditions. The resistant strains did not differ significantly from the susceptible strains tested in the absence of carbaryl treatment.
The resistant strains were released in almond orchards where they survived arbaryl applications, controlled spider mite populations, and overwintered. This is believed to be the first time that the field effectiveness of a biological control agent has been improved through artificial selection.
102 citations
TL;DR: Most field strains of Plutella xylostella in Taiwan developed resistance to the four major synthetic pyrethroids and fenvalerate resistance in the diamondback moth lacked sex linkage and was partially recessive and due to more than one gene.
Abstract: Most field strains of Plutella xylostella (L.) in Taiwan developed resistance to the four major synthetic pyrethroids—permethrin, cypermethrin, decamethrin, and fenvalerate—and the resistance levels to the three α-cyano 3-phenoxybenzyl esters were generally higher than that to permethrin. A diazinon-resistant strain showed significant cross resistance to all four compounds, whereas a methomyl-resistant strain had slight, yet consistent negative cross resistance to these compounds, except fenvalerate. Synergism of pyrethroid toxicity by piperonyl butoxide, but not DEF, was observed against a highly resistant strain. Fenvalerate resistance in the diamondback moth lacked sex linkage and was partially recessive and due to more than one gene.
90 citations
TL;DR: An avermectin, Merck MK-933, was a highly effective larvicide against horn flies, Haematobia irritans, stable flies, Stomoxys calcitrans, face flies, Musca autumnalis De Geer, and house flies.
Abstract: An avermectin, Merck MK-933 [at least 80% 22,23-dihydro-5- O -demethylavermectin A10 and not more than 20% 22,23-dihydro-5- O -demethyl-25-de(1-methylpropyl)-25-(1-methylethyl)avermectin A10], was a highly effective larvicide against horn flies, Haematobia irritans (L.), stable flies, Stomoxys calcitrans (L.), face flies, Musca autumnalis De Geer, and house flies, M. domestica L. When given to cattle daily in an oral capsule, 1 μg/kg per day killed all horn fly larvae in the manure. Daily oral dosages of 5 μg/kg killed all of the face flies, ca. 60% of the stable flies, and 90% of the house flies in the manure. Cattle dosed at 20 μg/kg per day resulted in >90% mortality of stable fly larvae in the manure. Additionally, daily subcutaneous injections of MK-933 at a rate of 5 μg/kg per day prevented horn fly development in the manure, but injections of 10 mg/kg per day did not control stable fly larvae. A single injection of 200 μg/kg, the anthehmntic dosage, controlled horn flies in the manure for up to 4 weeks posttreatment.
88 citations
TL;DR: The roles of type A and B gladular trichomes in defense of the wild potato species, Solanum berthaultii Hawkes, agamst the green peach aphid, Myzus persicae, and Potato leafhopper, were assessed.
Abstract: The roles of type A and B gladular trichomes in defense of the wild potato species, Solanum berthaultii Hawkes, agamst the green peach aphid, Myzus persicae (Sulzer), and Potato leafhopper, Empoasca fabae (Harris), were assessed. Mortality of fourth-stadium M. persicae and encasement of tarsi and labia by type A exudate increased with a rise in density and volume of type A trichomes. Tarsi coated by type B exudate were highly adhesive and extremely effective in discharging type A trichomes. Immature stages of M. persicae and E. fabae were subject to greater mortality and encasement of body parts by trichome exudate than were adults.
85 citations
TL;DR: Temperature had a pronounced effect on the decay rate of chlorpyrifos in Sultan silt loam during a 24-week incubation period at 15°, 25°, and 35°C; initial half-lives were 25, 13, and 6 weeks, respectively.
Abstract: The decomposition of 14C-ring-labeled chlorpyrifos was followed in 2 soils for a 32-week period under laboratory conditions at 25°C Time required for 50% loss of parent compound in Chehalis clay loam and Sultan silt loam was 4 and 12 weeks, respectively Faster breakdown of the insecticide in the clay loam was due to microbial degradation since initial halflives of 24 weeks were observed in both autoclaved soils Radioactivity from degraded chlorpyrifos was recovered as 3,5,6-trichloro-2-pyridinol, as expired CO2, and as a nonextractable soil-bound residue component After 32 weeks, 47% of the radioactivity from degraded insecticide were recovered as CO2 in the clay loam as compared to only 8% in the silt loam
Temperature had a pronounced effect on the decay rate of chlorpyrifos in Sultan silt loam during a 24-week incubation period at 15°, 25°, and 35°C; initial half-lives were 25, 13, and 6 weeks, respectively Soil moisture contents ranging from 3–20% did not affect insecticide degradation rates in the Sultan silt loam
84 citations
TL;DR: The effects of the organophosphate insecticide temephos on the reproductive potential of Culex quinquefasciatus Say was investigated, and the intrinsic rate of increase was found to be a more useful estimate of reproductive potential than fecundity or fertility alone.
Abstract: The effects of the organophosphate insecticide temephos on the reproductive potential of Culex quinquefasciatus Say was investigated on a resistant (RR) strain, a susceptible (SS) strain, and a heterozygous (RS) strain synthesized from them. Strains were treated as larvae at two to four mortality levels, and daily fertility and fecundity estimates were made on a sample of the adult survivors. From these data, the intrinsic rate of increase, r, was calculated. This measure was found to be a more useful estimate of reproductive potential than fecundity or fertility alone.
The RR strain that had been maintained under strong selection pressure before the study exhibited several classical effects of strong directional selection; it was less fecund, took longer to develop, and had poorer viability than a similar strain that had been maintained without selection. In addition, the reproductive potential of this strain was adversely affected at all three treatment levels investigated. The SS strain also was affected adversely by treatment, but the RS strain showed no apparent biotic effect.
61 citations
TL;DR: Dry powder commercial formulations of Bacillus sphaericus Neide 1593 and B. thuringiensis var.
Abstract: Dry powder commercial formulations of Bacillus sphaericus Neide 1593 and B. thuringiensis var. israelensis deBarjac were applied to test ponds at dosages equivalent to 0.5, 1, and 2 kg/ha. Natural populations of the Australian encephalitis vectors, Culex quinquefasciatus Say and C. annulirostris Skuse, and a potential malaria vector, Anopheles annulipes Walker, were controlled at 1 and 2 kg/ha. No evidence of residual activity beyond day 2 was seen in assessment of natural repopulation of ponds or in mortality of caged larvae confined in test ponds. B. sphaericus 1593 and B. thuringiensis var. israelensis were very similar in efficacy in these tests.
51 citations
TL;DR: Metaseiulus occidentalis (Nesbitt), a spider mite predator, was selected for resistance to methomyl, dimethoate, and carbaryl in the laboratory, and the carbaryl resistance appears to be inherited as a single dominant gene.
Abstract: Metaseiulus occidentalis (Nesbitt), a spider mite predator, was selected for resistance to methomyl, dimethoate, and carbaryl in the laboratory. Two colonies were selected with each pesticide. All responded to selection, although the methomyl and dimethoate resistance levels achieved were low. The carbaryl resistance appears to be inherited as a single dominant gene. Reasons for the absence of carbaryl resistance in the field are discussed.
50 citations
TL;DR: The laboratory studies have shown that the effectiveness of the bacterium as a larvicide can be influenced by several factors, such as the species and in star of black fly, temperature, formulation, and prod uct manufacturer (Molloy et al. 1981).
Abstract: J. Econ. Entomol. 74: 314--3 18 ( 1981} When a small stream was treated at 0.5 ppm/15 min (l3°C) with an aqueous suspension of unformulated Bellon primary powder of Bacillus thuringiensis Berliner var. israelensis, 96, 86, 53, and 11% reductions occurred , respectively , in larval populations of Simulium spp . black flies at 20, 180, 350, and 705 m below the treatment point. In contrast, the number of black fly larvae declined by only 5% in the upstream control. Mortality occurred within 2-3 days of treatment , with few dead larvae remaining attached by the 5th day posttreatment. The mortality rates of larvae transported to and reared in the laboratory for 48 h posttreatment closely corresponded to the rates recorded in the stream. Significantly higher mortality rates occurred among smaller larvae . In contrast to the sharp reduction (89%) in black fly larvae in the 20-350 m area below the treatment point, Surber samples indicated increases in mayfly (35%), caddisfly (47%), stonefly (75%) , chironomid (19%), and elmid (242%) populations. Thus , no adverse effect on any of these nontarget populations was evident following stream treatment. Varieties of Bacillus thuringiensis Berliner which are active against lepidopterans were shown to be relatively ineffective against mosquitoes (Hall et al. 1977) and black flies (Lacey and Mull a 1977). Consequently, this bacterium had been considered to have little potential as a biological control agent of these medically impor tant insects. The discovery of a new strain of B. thurin giensis, however, and the demonstration of its high pathogenicity to mosquitoes renewed interest in this bac terium (Goldberg and Margalit 1977) . The strain was determined to be a new serotype (H-14) and was de scribed as B. t. var. israelensis (de Barjac 1978). The laboratory effectiveness of this new variety as a black fly larvicide was subsequently demonstrated against Cnephia, Prosimulium, and Simulium spp., including the West African vector of onchocerciasis S. damnosum Theobald s. I. (Undeen and Berl 1979, Undeen and Nagel 1978). Our laboratory studies have shown that the effectiveness of the bacterium as a larvicide can be influenced by several factors, such as the species and in star of black fly, temperature, formulation, and prod uct manufacturer (Molloy et al. 1981). Reported here are results of a field trial with B. t. var . israelensis against Simulium spp. in the Adirondack Mountains of New York. Our primary objectives were: to determine the effective "carry" of the treatment (i.e., the distance downstream in which the bacteria continued to produce high mortality); to examine instar suscepti bility; and to monitor the effect of the treatment on non targt insect populations.
49 citations
TL;DR: Vegetable oils (cottonseed, soybean, maize, and peanut) were used to suppress Sitophilus granarius (L.) in wheat grain and repelled granary weevil adults.
Abstract: Vegetable oils (cottonseed, soybean, maize, and peanut) were used to suppress Sitophilus granarius (L.) in wheat grain. Insect progeny production decreased significantly at a 5-ml/kg dosage. At the 10-ml/kg level, complete control was achieved which lasted at least 60 days. These oils also repelled granary weevil adults. There was no obvious effect of the oil treatment on water absorption by the wheat seeds, but 5- or 10-ml/kg dosages reduced seed germination.
TL;DR: The activity of this chemical at such low dosage levels makes it an excellent candidate as an acaricide for the control of ticks systemically.
Abstract: Merck MK-933 (7-\[[2,6-dideoxy-4- O -(2,6-dideoxy-3- O -methyl-α-L- arabino -hexopyranosyl)-3- O -methyl-α-L- arabino -hexopyranosyl]oxy]-3’,4’,5’6,6’,7,10,11,14,15,17a,20,20a,20b-tetradecahydro-20,20b-dihydroxy-5’,6,8,19-tetramethyl-6’-(1-methylpropyl)spiro[11,15-methano-2 H ,13 H ,17 H -furo[4,3,2- pq \]\[2,6\]benzodioxacyclooctadecin-13,2’-[2 H ]pyran]-17-one), an avermectin given orally to cattle daily by capsule, was highly effective in preventing engorgement and reproduction of adults of six species of three-host ticks—Amblyomma americanum (L.), A. cajennense (F.), A. maculatum Koch, Dermacentor andersoni Stiles, D. variabilis (Say), and Rhipicephalus sanguineus (Latreille)—and all parasitic stages of a one-host species— D. albipictus (Packard)—at dosages of >50 μg/kg per day. A daily subcutaneous injection of 10 μg/kg per day afforded complete control, but a similar injection of 5 μg/kg per day was not completely effective. MK-933 formulated as sustained-release tablets or boluses designed to release ca. 50 μg/kg per day was also effective, but the sustained-release devices eroded at rates higher or lower than those anticipated. The activity of this chemical at such low dosage levels makes it an excellent candidate as an acaricide for the control of ticks systemically.
TL;DR: Joint exfosure to Popillia japonica Newman of phenethyl propionate + eugenol + geraniol, 3:7:3, (PEG) and a synthetic female sex attractant (Japonilure) resulted in a lure of outstanding attractancy.
Abstract: Joint exfosure to Popillia japonica Newman of phenethyl propionate + eugenol + geraniol, 3:7:3, (PEG) and a synthetic female sex attractant (Japonilure) resulted in a lure of outstanding attractancy. This combination was more than 3.6 times as attractive as the current standard survey lure, phenethy1 propionate + eugenol, 3:7, (PE) and 1.34 times as attractive as PE + Japonilure PE + Japonilure however was 2.2 and 2.5 times more attractive, respectively, than either PEG or PE.
TL;DR: In laboratory tests conducted to determine the mechanisms of resistance of selected corn genotypes to Spodoptera frugiperda (J. E. Smith), the choice tests and leaf consumption data indicated that the resistance of Antigua 2D-118 was mainly non preference.
Abstract: In laboratory tests conducted to determine the mechanisms of resistance of selected corn genotypes to Spodoptera frugiperda (J. E. Smith), the choice tests and leaf consumption data indicated that the resistance of Antigua 2D-118 was mainly non preference. There was a low level of antibiosis. MpSWCB-4 had the highest level of resistance to the fall armyworm, with both nonpreference and antibiosis expressed.
TL;DR: C Cultures collected from corn and signalgrass, previously treated with carbaryl, near Hammond in 1979 exhibited resistance to carbaryl (41X), methyl parathion (113X), permethrin (17X), and trichlorfon (31X) in comparison to the laboratory culture.
Abstract: Larvae of Spodoptera frugiperda (J. E. Smith) from a laboratory culture (originally collected from rice near Hammond, La.) reared on bermudagrass, corn, millet, and soybean were treated topically with carbaryl, methyl parathion, permethrin, and trichlorfon to establish log dose-probit lines for each insecticide on each host. Differences among hosts were not detected ( P < 0.05) in the toxicological response of larvae treated with methyl parathion. Larvae reared on millet were 6X more susceptible ( P < 0.05) to trichlorfon than larvae reared on the other 4 hosts. Larvae reared on bermudagrass and millet were more susceptible ( P < 0.05) to carbaryl and permethrin than larvae reared on corn, cotton, or soybean. Cultures collected from corn and signalgrass, previously treated with carbaryl, near Hammond in 1979 exhibited resistance to carbaryl (41X), methyl parathion (113X), permethrin (17X), and trichlorfon (31X) in comparison to the laboratory culture.
TL;DR: As annual cropping systems gradually replace swidden agriculture in the neotropics, the ant fauna inhabiting these highly disturbed environments seems to hold special promise in controlling certain pests such as rootworms.
Abstract: Experiments conducted in Costa Rica showed that 2 species of ants, Solenopsis geminata F. and Pheidole sp., were important predators of rootworm eggs. In field experiments, the ants removed ca. 80% of the rootworm eggs over a 3-day period and removal probably would be higher during the 6 days normally required for egg hatching. As annual cropping systems gradually replace swidden agriculture in the neotropics, the ant fauna inhabiting these highly disturbed environments seems to hold special promise in controlling certain pests such as rootworms.
TL;DR: Irrespective of species, stage of development, or exposure technique, dennettia oil was significantly more toxic to all the insects than the other 3 compounds.
Abstract: In assessing potential insecticidal activity of the essential oil of Dennettia tripetala G. Baker (Anonaceae), samples of the oil obtained by steam distillation from the edible fruits were tested against nymphs and adults of the American cockroach, Periplaneta americana (L.), and a grasshopper, Zonocerus variegatus (L.). For comparative assessment, diazinon, lindane, and propoxur also were tested.
Graded vol/vol dilutions in acetone of the various compounds were used for the tests, and testing was by the contact method, employing the treated surface exposure technique and the topical application technique.
Irrespective of species, stage of development, or exposure technique, dennettia oil was significantly more toxic to all the insects than the other 3 compounds.
TL;DR: Vegetable oil at a dosage of 1ml/kg bean seed, Phaseolus vulgaris (L.), showed insecticidal effectiveness against Zabrotes subfasciatus (Boheman) infesting stored beans.
Abstract: Vegetable oil at a dosage of 1ml/kg bean seed, Phaseolus vulgaris (L.), showed insecticidal effectiveness against Zabrotes subfasciatus (Boheman) infesting stored beans. The active oil fraction appeared to be the triglyceride component. Oleic acid appeared to be the only effective fatty acid of the ones tested. Linolenic and arachidonic acid showed some insecticidal effect.
TL;DR: A male-produced aggregation pheromone in Sitophilus oryzae (L.) was detected in two closed laboratory bioassay systems and proved to be equally attractive to virgin and mated 6- to 7-day-old adult males and females.
Abstract: A male-produced aggregation pheromone in Sitophilus oryzae (L.) was detected in two closed laboratory bioassay systems. This pheromone proved to be equally attractive to virgin and mated 6- to 7-day-old adult males and females. Although mated males attracted virgin adults of both sexes, their attractance was less than that of virgin males. A new pitfall bioassay system was developed that traps insects lured to a source of attractant.
TL;DR: Farm-stored shelled corn and wheat in south-central and west-central Minnesota were sampled for insects during 1977 and 1978 and Cryptolestes spp.
Abstract: Farm-stored shelled corn and wheat in south-central and west-central Minnesota were sampled for insects during 1977 and 1978. The most common insects, in decreasing order, were Cryptolestes spp., Ahasverus advena (Waltl), Plodia interpunctella (Hubner), Cynaeus angustus (LeConte), Tribolium castaneum (Herbst), Typhaea stercorea (L.) and Oryzaephilus surinamensis (L.). A. advena and Cryptolestes spp. were the most abundant.
Of 38 bins of shelled corn sampled in South-Central Minnesota, 10 had 15 or more live adult insects per ca. 0.95-liter (1-qt) sample. Fifteen bins had 5 to 14 insects per ca. 0.95-liter sample. Mold-damaged areas were infested by numerous species simultaneously. Samples of grain collected at a local country elevator confirmed the similar frequencies of occurrence of the insect species detected in farm-stored grain. C. angustus was unexpectedly found to be both common and abundant in shelled corn.
TL;DR: Hydrolysis and volatility contributed to loss of 14C-ring-labeled chlorpyrifos on air-dried surfaces of SOils and soil clays in the laboratory and 3,5,6-trichloro-2-pyridinol was the only14C-breakdown product found in acetone extracts of aged, chlorp Pyrifos-treated soils and homoionic clays.
Abstract: Hydrolysis and volatility contributed to loss of 14C-ring-labeled chlorpyrifos on air-dried surfaces of SOils and soil clays in the laboratory. Dissipation rates were influenced by temperature, composition of the substrate, and level of hydration. Chlorpyrifos degraded rapidly via a temperature-dependent catalytic hydrolysis process on Sultan silt loam. Times for 50% degradation at 5, 15, 25, 35, and 45°C were >20, >20, 8, 3, and 1 day, respetively, when ambient RH levels were 93, 67, 38, 30, and 10%, respectively. The insecticide degraded even more rapidly on air-dried surfaces of calcium homoionic clays (illite, vermiculite, adkaolinite) and clay separates isolated from Sultan silt loam and Chehalis clay loam. Degradation was slower on a sandy loam, on montmorillinite, and on an organic soil and negligible on pulverized peat moss and quartz sand. An increae in the sorbed water content of air-dried substrates decreased the rate of the clay-catlyzed hydrolysis reaction and increased the volatilization rate of 14C from mineral substrate surfaces. 3,5,6-trichloro-2-pyridinol was the only 14C-breakdown product found in acetone extracts of aged, chlorpyrifos-treated soils and homoionic clays.
TL;DR: Testing of a strain of Colorado potato beetle from Sherbrooke, Quebec, was resistant to most of the insecticides currently recommended for use as compared with a susceptible strain from London, Ontario, suggesting that resistance to aldicarb and the pyrethroid insecticides may also soon occur.
Abstract: Laboratory tests showed that a strain of Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say), from Sherbrooke, Quebec, was resistant to most of the insecticides currently recommended for use as compared with a susceptible strain from London, Ontario. The level of resistance shown by the Sherbrooke strain to carbofuran was very high (> × 1,600). This strain was resistant also to DDT, endrin, endosulfan, azinphosmethyl, phosmet, methidathion, methamidophos, phorate, chloethocarb, and carbaryl. Aldicarb and some pyrethroid insecticides were toxic to both CPB strains. However, the Sherbrooke strain was slightly more tolerant (× 1.3) to aldicarb than the London strain and also showed low-level (≤ × 2.0) cross resistance from DDT to the pyrethroid insecticides. These results suggest that resistance to aldicarb and the pyrethroid insecticides may also soon occur.
TL;DR: The provision of food to the midge and the mosquito larvae impaired the effectiveness of each B. thuringiensis serovar.
Abstract: Three wettable powders (WP), IPS-78, R-153-78, and ABG-6108, and one flowable concentrate (FC), SAN-402-WDC, of Bacillus thuringiensis serovar. Israelensis de Barjac were tested in the laboratory against Ist- and 3rd-instar Glyptotendipes paripes Edwards, and 3rd-instar Chironomus crassicaudatus Malloch, C. decorus Johannsen, and Tanytarsus spp. The B. thuringiensis serovar. israelensis formulations also were tested against 3rd-instar Aedes aegypti (L.), and Culex quinquefasciatus Say.
The R-153-78 was invariably the most active preparation against midges (LC90 = 4.56-9.84 ppm) and mosquitoes (LC90 = 0.13 and 0.24 ppm) followed by IPS-78 The LC90 of the midge species ranged from 4.56 to 47.02 ppm, whereas the same range for the mosquitoes was 0.13 to 0.99 ppm. The 1st-instar G. paripes was 10- to 14-fold more susceptible to B. thuringiensis serovar. israelensis than its 3rd instar. The mosquito larvae were 13;-to 75-fold more susceptible to the various B. thuringiensis serovar. israelensis preparations than were the midge larvae even at half the exposure time. The provision of food to the midge and the mosquito larvae impaired the effectiveness of each B. thuringiensis serovar. israelensis formulation.
TL;DR: Dissections of the alimentary tract of two of the more important mole cricket pests in the southeastern United States revealed different feeding habits.
Abstract: Dissections of the alimentary tract of two of the more important mole cricket pests in the southeastern United States revealed different feeding habits. A total of 411 nymphs and female mole crickets, field collected from grass and sand habitats by drenching with pyrethrin solution, was examined. Scapteriscus acletus Rehn and Hebard was observed to be principally carnivorous and S. vicinus Scudder to be herbivorous.
TL;DR: Longevity of adult Cydia pomonella (L.) was increased 6–12 days when provided water, a carbohydrate, or a carbohydrate-protein solution, however, providing these foods or the increased longevity did not significantly increase mating, oviposition, or viability of eggs.
Abstract: Longevity of adult Cydia pomonella (L.) was increased 6–12 days when provided water, a carbohydrate, or a carbohydrate-protein solution. However, providing these foods or the increased longevity did not significantly increase mating, oviposition, or viability of eggs. Regardless of the availability of water or food, moths laid 90% of their eggs within the 1st 5 days of life.
TL;DR: Dosage-mortality studies with permethrin against males of Pectinophora gossypiella (Saunders) indicated that percent mortalities occurring 96 h after dosing were more stable and reliable as dosage-dependent responses than those which occurred at 48 h.
Abstract: Dosage-mortality studies with permethrin against males of Pectinophora gossypiella (Saunders) indicated that percent mortalities occurring 96 h after dosing were more stable and reliable as dosage-dependent responses than those which occurred at 48 h. Tests measuring percent mortality, percent prostration, and uncoordinated behavior for 12 days after dosing showed that, regardless of dosage, ca. 90% of the total mortality occurred in the first 96 h. Although prostrate and uncoordinated behavior were high in the first 96 h, it was negligible for the remaining time. Activation (wing fanning) responses by male survivors of 96-h LD50 and LD80 dosages of permethnn were reduced 0.5- to 0.05-fold as compared with controls over a range of gossyplure concentrations from 0.01 to 1.0 μg Mating experiments showed that 96-h LD50 and LD80 male survivors mated as frequently as controls when confined to small mating cages with three virgin females for a 7-day period.
TL;DR: In laboratory trials with Bacillus thuringiensis Berliner var.
Abstract: In laboratory trials with Bacillus thuringiensis Berliner var. israelensis de Barjac against Simulium larvae, the following factors significantly influenced efficacy: black fly instar and species, formulation, temperature, and product manufacturer.
Mortalities were consistently higher among smaller larvae, e.g., after 15 min exposures with Bellon Laboratory primary powder at 11°C, the LC90 value for 2nd–5th instars (111 ppb) was significantly lower than for 7th instars (615 ppb). S. verecundum Stone and Jamnback larvae were significantly more susceptible than S. vittatum Zetterstedt to Bellon primary powder. In trials comparing Bellon preparations by total product weight, significantly higher mortalities were achieved with primary powder than with other preparations. No difference in efficacy, however, was evident between Bellon WP and primary powder when compared solely on the basis of the weight of their AI (Bellon wettable = 50% AI (wt/wt), while Bellon primary = 100% AI). Both the Bellon aqueous suspension and emulsion were less effective than the WP and primary powder. Results with the emulsion were erratic due to adverse effect on feeding behavior. Microscopic observation of test larvae revealed abnormal clumping of their cephalic fan rays and inhibition of normal feeding during exposure to the emulsion. Mortality among S. vittatum larvae treated at 20°C was twice that recorded at 10°C. Tests with Abbott and Bellon primary powders showed the Bellon preparation to be 3 to 4 times more toxic.
TL;DR: Sixty-nine % of all larvae found on plants exhibiting a resistant reaction were alive even though the plants appeared healthy; therefore, plant stunting does not seem to be a prerequisite for larval survival.
Abstract: Biotypes J and L of Mayetiola destructor (Say) were discovered in a field of ‘Arthur 71’ wheat in Randolph County, Indiana, in 1978. Neither biotype had been previously found in the wild; however, Biotype L had been selected in the laboratory. These 2 new biotypes can infest wheats having the H5 gene for resistance, heretofore resistant to all known Hessian fly biotypes. Biotypes B and D also were found but at a lesser frequency than biotypes J and L. With increased hectarage grown to wheats such as Arthur 71 having the H5 gene for resistance, the frequency of new biotypes that infest wheat with this source of resistance is expected to increase. Sixty-nine % of all larvae found on plants exhibiting a resistant reaction were alive even though the plants appeared healthy; therefore, plant stunting does not seem to be a prerequisite for larval survival.
TL;DR: Trichogramma nubilale Ertle and Davis was used at 2 different release rates in smallscale field tests against the European corn borer in sweet peppers, demonstrating an inverse relationship between plant growth and parasitism similar to the results obtained in previous studies on corn.
Abstract: Trichogramma nubilale Ertle and Davis was used at 2 different release rates in smallscale field tests against the European corn borer, Ostrinia nubilalis (Hubner), in sweet peppers. A parasitism rate of host egg masses averaging 80% was obtained on plants having leaf surface areas (LSA) equal to that of mature, commercial peppers i.e., 5500 cm2. As the LSA/plant increased to unusually large size, i.e., 8000 cm2, parasitism rates declined, demonstrating an inverse relationship between plant growth and parasitism similar to the results obtained in our previous studies on corn.
TL;DR: Infection of twospotted spider mites and fungal development, although significantly reduced from that measured at higher temperatures, occurred at 5°C.
Abstract: Tetranychus urticae Koch was found on feral host plants during the winter months. Individual mites collected in January with the physical appearance of being in diapause laid eggs immediately when placed on excised lima bean leaves at 27°C and 16-h photoperiod. A pathogenic1 fungus, Entomophthora floridana Weiser and Muma, was found in a viable state throughout the winter. Laboratory studies indicated that the fungus can maintain itself at low winter temperatures common to eastern North Carolina. Infection of twospotted spider mites and fungal development, although significantly reduced from that measured at higher temperatures, occurred at 5°C.