Showing papers in "Environmental Entomology in 1981"
TL;DR: Review of the biosystematic, archaeological, and historical records indicates that D. virgifera sensu lato and D. l.
Abstract: Among the species of the genus Diabrotica that occupy the United States, voltinism and adult collection sites are closely related to the presence of suitable larval hosts; thus, species in the fucata group are multivoltine polyphags and species in the virgifera group are univoltine oligophags (or monophags). The group-specific differences in voltinism are attributed directly to the seasonal availability of the host plant and only indirectly to the climate.
In the virgifera group, univoltinism combined with a narrow larval host range and limited search capability suggest that oviposition behavior is the primary determinant of whether the newly hatched larvae reach a suitable host. Review of the biosystematic, archaeological, and historical records indicates that D. virgifera sensu lato and D. l. barberi Smith and Lawrence have become pests of corn by convergent evolutlon. This evolutionary view suggests new avenues of research that are discussed in the text
165 citations
TL;DR: Seasonality and habitat preference of 34 species of carabid beetles were investigated in soybean, Glycine max Merrill, agroecosystems during 1978–79, and Harpalus pensylvanicus DeG.
Abstract: Seasonality and habitat preference of 34 species of carabid beetles were investigated in soybean, Glycine max Merrill, agroecosystems during 1978–79. Habitats included conventional and conservation tillage systems of soybeans and adjacent areas of a fescue pasture, old field (mixed annual grasses and herbaceous plants), and mixed hardwood-pine woodlot. Pitfall trapping indicated greatest carabid abundance in mid-spring and late summer. Populations often were several-fold greater in conservation than conventional tillage soybeans. Harpalus pensylvanicus DeG. was the dominant species in all habitats, except the conventionally tilled soybeans. Mark/recapture experiments indicate carabid movement from field and fescue border areas into soybean fields of either type tillage system.
93 citations
TL;DR: Larvae of the common green lacewing, Chrysopa carnea Stephens1, have a remarkable natural tolerance to pyrethroids, providing important selectivity in integrated control programs, and pyrethroid esterase is a major factor contributing to this tolerance.
Abstract: Larvae of the common green lacewing, Chrysopa carnea Stephens1, have a remarkable natural tolerance to pyrethroids, providing important selectivity in integrated control programs. A portion of this tolerance is attributable to detoxification by pyrethroid esterase(s). This larval enzyme(s) has unusually high activity and a unique specificity for hydrolyzing cis -permethrin and -cypermethrin two- to three-fold faster than the corresponding trans -isomers. Deltamethrin is also hydrolyzed rapidly. Certain properties of the larval pyrethroid esterase(s) parallel the sensitivity of the larvae to pyrethroid poisoning. Larval pyrethroid esterase(s) increases in activity for hydrolyzing trans -permethrin on larval growth in agreement with the increased tolerance to trans -permethrin poisoning. The relative rates of hydrolysis of deltamethrin and the cis - and trans -isomers of permethrin and cypermethrin by the larval pyrethroid esterase(s) generally coincide with the tolerance of the larvae to these pyrethroids. Phenyl saligenin cyclic phosphonate, a potent inhibitor for larval pyrethroid esterase, synergizes trans -permethrin toxicity by 68-fold from an LD50 of 17,000 μg/g to one of 250 μg/g. Although the involvement of penetration rates, nerve sensitivity, and oxidative detoxification has not been evaluated, it is clear that pyrethroid esterase(s) is a major factor contributing to the natural pyrethroid tolerance of lacewing larvae.
88 citations
TL;DR: The active distance estimates were used to design an optimal monitoring trap deployment strategy to minimize attraction of males from areas surrounding orchards and Bossert and Wilson's equation for active space should be altered so that active space is defined as the space where pheromone concentration is within both lower and upper thresholds for a particular behavior.
Abstract: The distance from the pheromone source at which Grapholitha molesta (Busck) males initiated walking, upwind flight, or wing fanning while walking varied directly with the pheromone emission rate. Roughly a 10-fold increase in emission rate resulted in a ca. 2-fold increase in mean maximum distance for initiation of these behaviors. Also, an apparent upper concentration threshold in males caused upwind flight to be terminated at increasing distances from the source with increasing emission rates. Thus, upper and lower thresholds apparently determine the boundaries of the “active distance” for upwind flight. There was much daily variation in mean maximum active distance, possibly due to temperature effects upon male threshold. The active distance estimates were used to design an optimal monitoring trap deployment strategy to minimize attraction of males from areas surrounding orchards. Using Bossert and Wilson's equation for active space, the average lower (initiation) threshold for upwind flight was 7.2 × 10−17 g/cm3 and the upper (termination) threshold was 2.1 × 10−13 g/cm3. Their model should be altered so that active space is defined as the space where pheromone concentration is within both lower and upper thresholds for a particular behavior.
88 citations
TL;DR: During a 3-year study, 522 overwintered individuals among 47 species of Pentatomidae, Scutelleridae, Corimelaenidae, Cydnidae, Coreidae, and Reduviidae emerged into cages placed over ground litter in 6 habitats.
Abstract: During a 3-year study, 522 overwintered individuals among 47 species of Pentatomidae, Scutelleridae, Corimelaenidae, Cydnidae, Coreidae, and Reduviidae emerged into cages placed over ground litter in 6 habitats. Among economically important pentatomids, Euschistus servus (Say) was most abundant and preferred open habitats, whereas E. tristigmus (Say) and Podisus maculiventris (Say) overwintered in deciduous woods and their borders. Acrosternum hilare (Say) preferred deciduous woods. Nezara viridula (L.) was found to overwinter primarily in above-ground habitats. Euthyrhynchus floridanus (L.) overwintered as eggs behind tree bark.
No N. viridula survived the winter when caged over wild radish, deciduous leaf litter, or soybean stubble. Only 9% of the A. hilare caged over leaf litter survived during 1976 and 1977. Weather data suggest that absence of N. viridula in South Carolina during 1977 and 1978 was due to the two previous severe winters.
Most overwintered A. hilare survivors emerged during early April; E. servus and E. tristigmus emerged from late March through April. Spring emergence was stimulated by increasing temperatures.
87 citations
TL;DR: It is proposed that southern pine forests, the southern pine beetle, Dendroctonus frontalis Zimmermann, and fire interacted historically within the geoclimatic regime of the Coastal Plain to maintain the structure and function of the southeastern coniferous forest.
Abstract: We propose a hypothesis that southern pine forests, the southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Scolytidae), and fire interacted historically within the geoclimatic regime of the Coastal Plain to maintain the structure and function of the southeastern coniferous forest. Fire regulates the regeneration in space and time of pine forests necessary for D. frontalis occurrence; D. frontalis regulates the occurrence and turnover of patches of dead trees conducive to burning and windthrow. This interaction led to high community diversity and productivity, enabling these forested ecosystems to reduce nutrient losses and to respond rapidly to disturbance. Current silvicultural practices have disrupted these interactions and created forests particularly susceptible to D. frontalis . Applications of our hypothesis to development of forest management practices are discussed.
85 citations
TL;DR: Insect colonization of collards in contiguous weedy and weed-free plots was monitored in 1978 and 1979 and Predator response were generally inefficient, especially when overall aphid densities were low.
Abstract: Insect colonization of collards in contiguous weedy and weed-free plots was monitored in 1978 and 1979. Green peach aphids, Myzus persicae (Sulzer) preferentially invaded weed-free collards and developed higher densities thereon. Numbers of Chrysopa oculata (Say), Coccinellidae, and Syrphidae were higher in plots in which weeds were uncut, despite lower aphid densities. When weeds were trimmed to 10 cm maximum height, predators became more numerous on weedless collards. Predator response were generally inefficient, especially when overall aphid densities were low.
84 citations
TL;DR: The predatory capabilities of nymphal and adult Orius insidiosus (Say) preying on larval and adult soybean thrips, Sericothrips variabilis (Beach), were assessed under laboratory conditions and appeared to feed past satiation at the high densities of soybean thrive.
Abstract: The predatory capabilities of nymphal and adult Orius insidiosus (Say) preying on larval and adult soybean thrips, Sericothrips variabilis (Beach), were assessed under laboratory conditions. Effects of varying densities of adult soybean thrips on predation by adult O. insidiosus were also determined.
All stages of O. insidiosus tested were able to successfully capture 1st- and 2nd instar larvae and adult soybean thrips. The average number of soybean thrips killed per 24-h period increased with successive nymphal stages of O. insidiosus , and adult females killed more soybean thrips than did adult males. Adult male and female O. insidiosus exhibited a type-II functional response when exposed to varying densities of adult S. variabilis . Adult O. insidiosus appeared to feed past satiation at the high densities of soybean thrips.
81 citations
TL;DR: Bioassaying soil and duff samples from an area in which the last tussock moth outbreak took place in 1936–38 indicates the duff has accumulated since the last epizootic of tussocks moth nuclear polyhedrosis.
Abstract: The long-term persistence of the nuclear polyhedrosis virus of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), in forest soil has been established by bioassaying soil and duff samples from an area in which the last tussock moth outbreak took place in 1936–38. Samples were taken from beneath each of 75 white fir, Abies concolor (Gord. and Glend.) Lindl., trees selected within 17 clusters in a study area in the Inyo National Forest, California. Virus was present in 15 soil samples from 9 of the clusters. Although present concentrations of active virus are low (<45 PIB/cm3), enough remains in the mineral soil from sheltered locations to infect tussock moth larvae. Absence of active nuclear polyhedrosis virus in the duff layers above the positive soil samples indicates the duff has accumulated since the last epizootic of tussock moth nuclear polyhedrosis.
79 citations
TL;DR: Twenty-seven species of insects and spiders representing 6 orders and 15 families were tested for both egg and nymphal predation of Nezara viridula (Hemiptera: Pentatomidae) using an enzyme linked immunosorbent assay (ELISA).
Abstract: Twenty-seven species of insects and spiders representing 6 orders and 15 families were tested for both egg and nymphal predation of Nezara viridula (Hemiptera: Pentatomidae) using an enzyme linked immunosorbent assay (ELISA). The efficiency of each predator species was determined by a combination of its population density and results of the ELISA. Two predator complexes comprized of 8 species plus Cocinellidae larvae as a group, accounted for 91.4% and 95.4% of the egg and nymphal predation, respectively. Predation had to be viewed in the context of a complex which changed in its temporal composition.
76 citations
TL;DR: It was found that seeds of some species are fed upon by bruchids only after they have fallen to the ground (after dispersal), and that there are 3 guilds of bruchid beetles that attack legume seeds at different times and different ways.
Abstract: Data concerning the life histories of 23 species of leguminous plants and 16 species of bruchids that attacked their seeds were gathered and analyzed. It was found that there are 3 guilds of bruchid beetles that attack legume seeds at different times and different ways; the genera in the guild that oviposits on legume pods are different from the genus that oviposits on seeds; there are 3 patterns of pod dehiscence that correspond to 3 patterns of seed dispersal; the 3 guilds of bruchids do not correspond on a one-to-one basis with the 3 patterns of pod dehiscence but rather all 3 bruchid guilds may attack one species of partially dehiscent legume; and finally that seeds of some species are fed upon by bruchids only after they have fallen to the ground (after dispersal).
TL;DR: When seasonal variation of caste proportions was quantified in “nests” of the subterranean termite Reticulitermes flavipes (Kollar), workers comprised the most abundant caste, with a 2-year average of 84.0% of the individuals.
Abstract: When seasonal variation of caste proportions was quantified in “nests” of the subterranean termite Reticulitermes flavipes (Kollar), workers comprised the most abundant caste, with a 2-year average of 84.0% of the individuals. Larvae comprised 8.7%, nymphs 5.0%, adult soldiers 2.1%, and presoldiers and neotenic reproductives 0.1% each. Alates and eggs were found infrequently. Caste proportions changed significantly with season, apparently varying according to the reproductive cycle. Larvae are most abundant in the summer and least abundant in the winter. Soldiers were most abundant immediately preceding alate flights, and least abundant immediately thereafter. Nymphs showed two peaks of abundance (early fall and early summer). Workers were most abundant during the spring and summer months.
TL;DR: Low level stress in spider mite populations caused reductions in physiological parameters at much lower population levels than was necessary to cause similar injury later in the season, and reduced physiological activity of mite-stressed plants persisted until plant recovery was observed.
Abstract: Studie were conducted in 1978 and 1979 to evaluate the effects of varying twospotted spider mite populations on photosynthesis, transpiration, and productivy of strawberry plants under field conditions. Both photosynthesis and transpiration were significantly reduced by high levels of spider mite populations. Early season infestations caused reductions in physiological parameters at much lower population levels than was necessary to cause similar injury later in the season. Reduced physiological activity of mite-stressed plants persisted until plant recovery was observed following a rapid decline in spider mite populations. The number of fruit produced was significantly increased from plants experiencing low level stress from mite populations. After the initial increase, the number of fruit from infested plants decreased significanyly and the difference was greatest from plants that experienced early season stress. Fruit size was reduced significantly for all mite-stressed plants.
TL;DR: Dispersal of the predatory phytoseiid mite Amblyseius fallacis (Garman) within the ground cover, the air beneath the tree canopy, on the tree trunk and on tree foliage of commercial apple orchards during a growing season is described.
Abstract: Dispersal of the predatory phytoseiid mite Amblyseius fallacis (Garman) within the ground cover, the air beneath the tree canopy, on the tree trunk and on tree foliage of commercial apple orchards during a growing season is described in relation to environmental factors and densities of A. fallacis and its prey Panonychus ulmi (Koch), Tetranychus urticae Koch, and Aculus schlechtendali (Nalepa) in the aforenamed habitats. Ambulatory and aerial means of dispersal were involved in initial colonization of trees by A. fallacis coming from the orchard ground cover. A mean total of 261°0 (base 12.2°C) since January 1 plus the presence of predators in the ground cover and prey in excess of one P. ulmi equivalent/apple leaf, i.e., the number of P. ulmi + T. urticae + ( A. schlechtendali /15) on an apple leaf, were prerequisites for tree colonization by A. fallacis . Aspects of density independent and dependent dispersal by A. fallacis from trees to sites within and beyond an orchard in response to prey are also reported.
TL;DR: Surveys from 1965 to 1977 of the native wild and introduced naturalized flora of the delta of Mississippi for F1 generation larvae of the overwintered population of Heliothis zea (Boddie) and H. virescens (F.) showed that H. zea larvae occurred at least 1 week earlier than H.virescens larvae.
Abstract: Surveys from 1965 to 1977 of the native wild and introduced naturalized flora of the delta of Mississippi for F1 generation larvae of the overwintered population of Heliothis zea (Boddie) and H. virescens (F.) showed that H. zea larvae occurred at least 1 week earlier than H. virescens larvae. Eight plant species supported populations of both Heliothis species. Both crimson clover and Geranium dissectum L. were major hosts of H. zea . Although brief high populations of H. virescens occurred on several plant species, G. dissectum was the only early-season host that supported high populations of H. virescens over an extended period of time.
TL;DR: Exposure of male or female pupae of either species to high temperature caused some failure to mate and reduced the fecundity of mated females but did not reduce hatchability of the eggs laid.
Abstract: Pupae of Ephestia cautella (Walker) and Plodia interpunctella (Hubner) were brief1y exposed to temperatures of 40, 45, or 50°C, and the effects on adult eclosion, mating, fecundity and fertility were determined. All males and females of both species were killed by a 2-h exposure to 50°C, but E. cautella was significantly more tolerant of exposure to 40 and 45°C than P. interpunctella . The median lethal time for exposure to 45°C was 7- to 8-fold longer in E. cautella than in P. interpunctella . Generally, exposure of male or female pupae of either species to high temperature caused some failure to mate and reduced the fecundity of mated females but did not reduce hatchability of the eggs laid. The percentage of mating failure depended to some extent on which sex was exposed and increased with temperature and length of exposure. Loss of fecundity was usually more severe when females rather than males were exposed.
TL;DR: Adult and larval population fluctuation of the South American fruit fly Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) has been determined and related to host availability.
Abstract: Adult and larval population fluctuation of the South American fruit fly Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) has been determined and related to host availability. A peak in the adult population on each host occurred five weeks after the peak in larval population. The average number of larvae per fruit is between 1–5 in large hosts (guava, peach and loquat) and it is smaller than one for small fruit (surinam cherry).
TL;DR: This paper discusses two identifiable types of validation criteria: risk-to-user or cost-benefit criteria for evaluating management models and rigorous statistical procedures to test research models.
Abstract: Validation is a critical stage in model development with at least two identifiable types: (1) risk-to-user or cost-benefit criteria for evaluating management models and (2) rigorous statistical procedures to test research models. Each type is discussed along with some quantitative validation tools. We emphasize that selection of inappropriate criteria can lead to unnecessary delays in implementation or use of poorly validated models.
TL;DR: Phytoseiulus macropilis and P. persimilis Athias-Henriot suppressed Tetranyehus urtieae Koch populations on greenhouse ornamental plants in Florida and Ohio experiments indicated the importance of introducing predators into low-density spider mite populations.
Abstract: Phytoseiulus macropilis (Banks) and P. persimilis Athias-Henriot similarly suppressed Tetranyehus urtieae Koch populations on greenhouse ornamental plants in Florida and Ohio experiments. Observations indicated the importance of introducing predators into low-density spider mite populations, since 1 to 3 weeks were required to effect control.
TL;DR: Production of Parapsyche cardis Ross and Diplectrona modesta Banks was estimated in two first-order southern Appalachian streams and suggests that the major impact of these net spinners is on the animal fraction of the seston.
Abstract: Production of Parapsyche cardis Ross and Diplectrona modesta Banks was estimated in two first-order southern Appalachian streams. One stream drains a natural undisturbed hardwood watershed and the other a watershed subjected to several disturbances, including clearcutting. Since 1968 the latter has been allowed to undergo natural succession. Both hydropsychid species were univoltine in each stream. Production estimates were higher for both species in the stream draining the disturbed watershed. This was attributed to: (1) More suitable habitat in the disturbed watershed consisting primarily of rock face habitat with large amounts of moss; (2) Higher densities of prey species in the disturbed watershed; and, (3) Potentially enhanced food quality resulting from a 200 fold greater NO3-N concentration in the disturbed stream. The estimates of animal food consumption required to support the combined production of P. cardis and D. modesta were 11.59 and 3.33 g/m2/yr on the disturbed and undisturbed watersheds respectively. These two species use <0.019% and <0.0063% of the total organic seston passing over each m2/yr on the disturbed and undisturbed watersheds respectively. However, estimates of animal tissue consumption are several times higher than the invertebrate drift from each watershed. The latter suggests that the major impact of these net spinners is on the animal fraction of the seston.
TL;DR: Goosegrass, Eleusine indica, large crabgrass, Digitaria sanguinalis, vaseygrass, Paspalum urvillei Steud.
Abstract: We studied the development and fecundity of Spodoptera frugiperda (Smith) on 16 food plants and an artificial bean diet We found highly significant differences in the amount of food consumed, larval duration, pupal weights, and egg production Goosegrass, Eleusine indica (L) Gaertn, large crabgrass, Digitaria sanguinalis (L) Scop, vaseygrass, Paspalum urvillei Steud, and coastal bermudagrass Cynodon dactylon (L) Pers, were the most suitable hosts for fall armyworm growth and development Yellow nutsedge, Cyperus esculentus L, Cyperus globulosus Aubl, and Texas panicum, Panicum texanum Buckl, were the least suitable
TL;DR: Indirect flight muscles in the rice water weevil, Lissorhoptrus oryzophilus Kuschel, are greatly reduced in adults during winter, but regeneration occurs in the spring just before adult exodus from overwintering sites.
Abstract: Indirect flight muscles in the rice water weevil, Lissorhoptrus oryzophilus Kuschel, are greatly reduced in adults during winter. Muscle regeneration occurs in the spring just before adult exodus from overwintering sites. Once adults establish themselves in a flooded rice-field, the indirect flight muscles degenerate as females begin oviposition. First-generation adults possess well-developed indirect flight muscles; they exit fields in which they develop. Large numbers fly to aestivo-hibernation sites where muscle degeneration promptly occurs. Some first-generation adults move to young rice, if available, where muscle degeneration and oviposition occurs.
TL;DR: Pheromone traps were found to be sensitive to low densities of tobacco budworm males, and early-season catches from these traps can be used to estimate field populations.
Abstract: A method is presented for estimating the relative density of tobacco budworm, Heliothis Virescens (F.), field populations from pheromone trap catches. Pheromone traps were found to be sensitive to low densities of tobacco budworm males. Early-season catches from these traps can be used to estimate field populations. Increasing densities of native females late in the season cause difficulty in estimating density accurately because of competition between native females and traps.
TL;DR: These stages were found to be resistant to extreme moisture conditions in various types of soils and used in developing a mathematical model of survival of the early instars under variable moisture conditions, and simulations are compared with field data.
Abstract: Egg and 1st-instar survival as a function of soil texture and moisture was estimated under laboratory conditions. These stages were found to be resistant to extreme moisture conditions in various types of soils. Delays in egg development were observed particularly in saturated soils. These results are used in developing a mathematical model of survival of the early instars under variable moisture conditions, and simulations are compared with field data. Field survival was highly variable and correlated only partially to model outputs. Probable causes of the discrepancies are discussed.
TL;DR: Three methods were used in determining the low-temperature threshold for pupal development of the western cherry fruit fly, Rhagoletis indifferens Curran, and indicated that least variation in predicted emergence was noticed by using an 8.3°C threshold.
Abstract: Three methods were used in determining the low-temperature threshold for pupal development of the western cherry fruit fly, Rhagoletis indifferens Curran. The standard x-intercept method using regression analysis of all data points (13.0, 15.5, 17.0, 19.5, 21.0, 22.0, 25.5°C) yielded a threshold of 10.2°C. A modified method using only median data points increased the threshold to about 13°C. A third method using oneway analysis of variance and taking into consideration the relative number of occurrences in the field of the various temperatures used as treatments in the experiment yielded a base threshold of 8.3°C. A comparison of effectiveness of the three proposed thresholds (8.3, 10.2, l1.7°C) indicated that least variation in predicted emergence was noticed by using an 8.3°C threshold.
TL;DR: Carabids inhabiting an Iowa cornfield during the summer of 1975 may have dispersed more readily than the other two species and evidently moved into the field from field borders during early to mid-August.
Abstract: Population density, dispersion, and dispersal were determined for the adult carabids, Pterostichus chalcites Say, Scarites substriatus Haldeman, and Harpalus pennsylvanicus DeGeer, inhabiting an Iowa cornfield during the summer of 1975. Population density estimates were calculated by a mark and recapture technique. Maximum population densities for P. chalcites , S. substriatus , and H. pennsylvanicus were 0.20 · m−2, 0.08 · m−2, and 0.39 · m−2, respectively. All three species had aggregated dispersion patterns, which were probably due to differences in the environment. Dispersal for P. chalcites and S. substriatus averaged 8.5 and 12.2 m/day, respectively, and individuals of these species were captured an average of 14 days after initial release. H. pennsylvanicus may have dispersed more readily than the other two species and evidently moved into the field from field borders during early to mid-August.
TL;DR: Neoaplectana bibionis Bovien was found to be considerably more effective for disinfesting blackcurrant cuttings of Synanthedon tipuliformis (Clerck) larvae than were two other insectparasitic rhabditid nematodes
Abstract: Neoaplectana bibionis Bovien was found to be considerably more effective for disinfesting blackcurrant cuttings of Synanthedon tipuliformis (Clerck) larvae than were two other insectparasitic rhabditid nematodes, Neoaplectana carpocapsae Weiser and Heterorhabditis heliothidis (Kahn et al.). This species of nematode caused 99.4 and 99.8% mortality of currant borer larvae in two commercial consignments of canes destined to establish some 12 ha of borer-free plantation.
Spraying bundles of cuttings, stacked as a wall, with 30,000 N. bibionis infective juveniles per ml was found to be a feasible method for economically dis infesting blackcurrant cuttings on a commercial scale.
No phytotoxic effects were observed following any of the treatments.
TL;DR: Six fungicides used in pecan culture were evaluated in vitro against the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin, both of which attack the pecan weevil.
Abstract: Six fungicides used in pecan culture were evaluated in vitro against the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin, both of which attack the pecan weevil, Curculio caryae (Horn). Triphenyltin hydroxide was the most toxic fungicide to both pathogens, followed by: benomyl, methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate; zineb, zinc ethylenebis [dithiocarbamate]; and dodine, n -dodecylguanidine acetate. Sulfur and dinocap, 2-(1-methylheptyl)-4,6-dinitrophenyl crotonate, were the least toxic.
TL;DR: The persistence of insecticidal activity of Bacillus thuringiensis Berliner (variety kurstaki , HD-1 strain) on cotton leaves in the field was determined in 1976 and 1977 by using two techniques and two insect species.
Abstract: The persistence of insecticidal activity of Bacillus thuringiensis Berliner (variety kurstaki , HD-1 strain) on cotton leaves in the field was determined in 1976 and 1977 by using two techniques and two insect species. In both years the insecticidal activity half-life was between 1.5 and 2 days.
TL;DR: Brood ball size and weight, manure burial rate, and offspring size of Onthophagus gazella (F.) were demonstrated to increase as the size of the parent beetles increased, indicating a trend toward a medium size.
Abstract: Brood ball size and weight, manure burial rate, and offspring size of Onthophagus gazella (F.) were demonstrated to increase as the size of the parent beetles increased. Adult size, in turn, reflected the quantity of provisions in the brood ball in which a beetle developed, regardless of the size of its parents. Also, under present experimental conditions, the sizes of the offspring from extremely large and small parents differed significantly from parental sizes, indicating a trend toward a medium size. The role of beetle size in dung ecology is discussed.