Showing papers in "Environmental Entomology in 1984"
TL;DR: Several guidelines concerning use of multiple-comparison procedures for comparing means, medians, or proportions are proposed, including specification of which test was used and why and a recommendation encouraging a switch to the use of confidence intervals instead of hypothesis tests.
Abstract: Multiple-comparison procedures for comparing means, medians, or proportions are commonly used by entomologists publishing in ecological and agricultural journals of the Entomological Society of America. Unfortunately, there is confusion among many researchers and reviewers with respect to the type I error rates of the various tests. The calculation of and reasoning behind the error rate and relative conservativeness or liberalness of each test are discussed. Several guidelines concerning use of these tests are proposed, including specification of which test was used and why, and a recommendation encouraging a switch to the use of confidence intervals instead of hypothesis tests. It is felt that adoption of these and other proposals for reporting results will increase the meaningfulness and scientific merit of published entomological research.
139 citations
TL;DR: The impact of herbivores may increase as the level of atmospheric carbon dioxide rises, and leaves of soybean plants grown under three carbon dioxide regimes were fed to soybean looper larvae, which altered the leaf content of nitrogen and water and to the leaf-specific weight.
Abstract: Rising atmospheric carbon dioxide may alter plant/herbivore interactions. The projected rise in atmospheric carbon dioxide is expected to increase plant productivity, but little evidence is available regarding effects on insect feeding or growth. Leaves of soybean plants grown under three carbon dioxide regimes (350, 500, and 650 µl/liter)were fed to soybean looper larvae. Larvae fed at increasingly higher rates on plants from elevated carbon dioxide atmospheres: 80% greater rates on leaves from the 650 µl/liter treatment than on leaves from the 350 µl/liter treatment. Variation in larval feeding was related to the leaf content of nitrogen and water and to the leaf-specific weight. each of which was altered by the carbon dioxide growth regime of the soybean plants. This study suggests that the impact of herbivores may increase as the level of atmospheric carbon dioxide rises.
132 citations
TL;DR: The results point out the danger of making conclusions about predation merely by observing predator and prey distributions, and draw attention to the need for more information about the effect of predators on prey behavior, particularly if a predator is being considered as a biological control agent.
Abstract: The density of the aquatic, predatory bugs Notonecta hoffmani and N. kirbyi was manipulated in stock troughs in the Santa Ynez Valley, Calif., to assess the predator's effect on mosquito larvae. Each trough was divided in half by a wooden partition, and notonectids were removed from one half and retained in the other. Over a 3-month sampling period very few large mosquito larvae or mosquito pupae were found on the side of the trough where notonectids were present, whereas large densities were observed on the side where notonectids were absent. To ensure that this was not an artifact of the side of the trough chosen for notonectid addition or removal, the predators were changed from one to the other. The same result was obtained. Although it is well known that notonectids are voracious predators of mosquito larvae, the experimental results can be adequately explained by selective mosquito oviposition. This hypothesis was supported by laboratory experiments in which adult mosquitoes laid the fewest eggs in tubs containing notonectids. Laboratory and field experiments also demonstrated that notonectids may disrupt mosquito egg rafts, but no evidence of a reduction in subsequent hatching success was obtained. These results point out the danger of making conclusions about predation merely by observing predator and prey distributions. They also draw attention to the need for more information about the effect of predators on prey behavior, particularly if a predator is being considered as a biological control agent.
117 citations
TL;DR: Kairomonal responses of the sawyer beetle and two predators to southern pine bark beetle attractant and inhibitor mixtures explain previously observed temporal and spatial arrival patterns of these insect associates to bark-beetle-infested southern pines.
Abstract: The kairomonal responses of the sawyer beetle, Monochamus titillator (F.), and two predators, Thanasimus dubius (F.) and Temnochila virescens (F.), to southern pine bark beetle attractant and inhibitor mixtures were monitored in a series of replicated field bioassays. Tests were conducted in the presence and absence of measurable populations of the southern pine beetle, Dendroctonus frontalis Zimmermann. At three different test sites, M. titillator responded to traps baited with pheromone mixtures attractive to southern Ips spp. ( I. avulsus [Eichhoff], I. grandicollis [Eichhoff], I. calligraphus [Germar]), particularly those also containing D. frontalis inhibitor. This sawyer exhibited a reduced numerical response to a combination of D. frontalis attractant and D. frontalis inhibitor, but no significant response to traps baited solely with D. frontalis attractant. This is the first report of a sawyer beetle responding to pheromones of coinhabiting pine bark beetles. The predator T. dubius was captured in greatest numbers in traps baited with D. frontalis attractant, and in significantly lesser numbers in traps containing Ips attractant. In contrast to T. dubius , the predator T. virescens responded almost exclusively to Ips attractant and showed little response to D. frontalis attractant. These kairomonal responses explain previously observed temporal and spatial arrival patterns of these insect associates to bark-beetle-infested southern pines.
113 citations
TL;DR: This is the first artificial long-range pheromone for a member of the true bugs (Hemiptera: Heteroptera) and the first such pheram for a nonsocial predaceous insect.
Abstract: A mixture of ( E )-2-hexenal, α-terpineol, linalool, terpinen-4-ol, and benzyl alcohol attracts adults of the predaceous spined soldier bug, Podisus maculiventris (Say). The male-produced pheromone contains (+)-α-terpineol; however, (−)-α-terpineol is not inhibitory to the bug, so artificial pheromone can be made with racemic α-terpineol. Four parasitic species use the pheromone as a kairomone and two of these parasitoids are partially inhibited by (−)-α-terpineol. This is the first artificial long-range pheromone for a member of the true bugs (Hemiptera: Heteroptera) and the first such pheromone for a nonsocial predaceous insect.
112 citations
TL;DR: Oviposition at dry sites was significantly greater than at wet sites, and Decomposing feed attracted significantly more oviposition than old chicken manure, but fresh chicken manure was not significantly different from these treatments.
Abstract: A method is described for quantifying Hermetia illucens (L.) (Diptera: Stratiomyidae) oviposition and for collecting large numbers of eggs. Individual egg mass weight mean was 29.1 mg, with a mean of 998 eggs per mass. Individual eggs weighed about 0.028mg and required 102 to 105 h to hatch at 24°C. All oviposition occurred at 0900 to 1900 h(EDST), with 86.5% of the total occurring at 1200 to 1700 h. Oviposition at dry sites was significantly greater than at wet sites. Decomposing feed attracted significantly more oviposition than old chicken manure, but fresh chicken manure was not significantly different from these treatments.
111 citations
TL;DR: Adult migration to cotton and soybeans in June and July was partly caused by a decrease in the number and maturation of many wild host plant species.
Abstract: Sweep-net samples taken at monthly intervals on wild and cultivated host plants at 15 locations in the delta of Arkansas, Louisiana, and Mississippi, were utilized to study the host plants and seasonal distribution of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois). Tarnished plant bugs were collected on 169 host plant species found in 36 plant families. The plant family having the largest number of host plant species was the Asteraceae, and 26.5% of all tarnished plant bug host plant species were in this family. Adult tarnished plant bugs were active on wild host plants each month of the year. The highest populations were found during May and June, and during September and October. Adult migration to cotton and soybeans in June and July was partly caused by a decrease in the number and maturation of many wild host plant species.
102 citations
TL;DR: Field studies show that natural enemies and moderate levels of glandular pubescence are compatible mortality factors in the management of aphids on potatoes, and greenhouse and laboratory studies elucidate the behavioral responses of natural enemies to glandular trichomes inadequately predict the effects of glandsular pubesence on beneficial insects in the field.
Abstract: Under greenhouse conditions there is a direct relationship between the density of glandular trichomes on aphid-resistant potato clones ( Solanum tuberosum x S. berthaultii , F3 and S. berthaultii ) and the adverse effectson 11 aphidophagous species. These negative effects include a reduction in adult coccinellid searching time, a decrease in the distance newly hatched chrysopid and coccinellid larvae move, and a decrease in the number of eggs Chrysopa oculata oviposit on highly pubescent foliage. Survival of the parasitoid Aphidius matricariae decreases when adults are exposed to moderate and high densities of glandular pubescence. However, the severe negative effects observed under greenhouse conditions are attenuated in the field. Field studies show that natural enemies and moderate levels of glandular pubescence are compatible mortality factors in the management of aphids on potatoes. Thus, although these greenhouse and laboratory studies elucidate the behavioral responses of natural enemies to glandular trichomes, they inadequately predict the effects of glandular pubescence on beneficial insects in the field.
93 citations
TL;DR: Permethrin-treated adult bees exhibited a significantly higher percentage of time in self-cleaning, trembling dance, abdomen tucking, rotating, and cleaning of abdomen while rubbing hind legs together, than untreated bees.
Abstract: Individually tagged honey bee foragers were treated topically with a sublethal dose of permethrin at a feeding station, and their behavior was observed inside an observation beehive. Permethrin-treated adult bees exhibited a significantly higher percentage of time in self-cleaning, trembling dance, abdomen tucking, rotating, and cleaning of abdomen while rubbing hind legs together. In contrast, untreated bees exhibited a higher percentage of time in walking, body insertion, and food giving, and made more foraging trips.
85 citations
TL;DR: A major reason levels of control achieved by Polistes in this study were not higher was the availability of alternate prey.
Abstract: We obtained a significant gain of weight and quality of cabbage in plots exposed to foraging Polistes wasps compared with cabbage in control plots. This reflects the significant reduction in numbers of large Pieris rapae larvae due to wasp predation. In 1980 the reduction in larvae did not show a corresponding reduction in damage and loss of yield. One average nest of wasps (5.6 wasps) was sufficient to reduce Pieris populations by up to five larvae (44%) on each of ca. 20 cabbage plants during the season. A major reason levels of control achieved by Polistes in this study were not higher was the availability of alternate prey.
85 citations
TL;DR: Some eggs underwent extended diapause, that is, following one winter in the field they did not hatch during 7 months at 25°C, but did hatch after a subsequent 4 months of chill, which has implications for the management of this pest.
Abstract: Eggs of the northern corn rootworm (NCR), Diabrotica barberi Smith and Lawrence, and the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, were placed in a soil pit outdoors at Brookings, S.D., in September (1982 for WCR, 1982 and 1983 for NCR) and removed from the pit at 20-day intervals through the winter to determine the pattern of termination of diapause under field conditions. Control eggs and eggs removed from the field were held in the laboratory at 25°C. With the WCR the percentage of egg hatch was the same whether the eggs had been incubated at 25°C in the laboratory or had been in the field for varying parts of the winter. A small percentage (<7%) of NCR eggs hatched without exposure to field conditions; hatch increased with increasing time in the field until midwinter, after which hatch was inconsistent. Some eggs underwent extended diapause. That is, following one winter in the field they did not hatch during 7 months at 25°C, but did hatch after a subsequent 4 months of chill. The occurrence of extended diapause has implications for the management of this pest.
TL;DR: A field study was conducted to examine the foraging pattern of the Formosan subterranean termite, Coptotermes formosanus Shirah A dye, Sudan Red 7B, was used as a marking material to identify foragers feeding at specific foraging sites.
Abstract: A field study was conducted to examine the foraging pattern of the Formosan subterranean termite, Coptotermes formosanus Shirah A dye, Sudan Red 7B, was used as a marking material to identify foragers feeding at specific foraging sites. The results showed that the termites selected their foraging sites at random. No preferences in foraging site were observed. Since foraging sites were selected at random, all of the foragers in a given colony would visit a specific foraging site, given sufficient time. It is theoretically possible, therefore, to introduce a suitable control agent in a single foraging site and eliminate the entire colony.
TL;DR: Physiological time was found to be much more realistic in describing population dynamics of this species than was calendar time.
Abstract: The response of Acyrthosiphon kondoi Shinji was evaluated at constant temperatures from 4.4 to 32.2°C. The lower and upper thresholds for development were calculated to be 3.45 and 27.1°C, respectively. Development and reproduction occurred at 4.4°C, but no development occurred at 32.2°C. At 29.4°C, aphids reached adulthood but failed to reproduce. The mean total developmental time was 144.93 ± 7.77 D°. The prepartum period for alates was 43% longer than for aptera. Mean physiological time to 50% mortality was 683.08 ± 50.47 D°, and mean reproductive period lasted 473.80 ± 37.26 D°. Maximum rm and minimum doubling time and mean generation time, on a physiological time scale, were at 10.0 to 18.3°C. The largest rm (0.0161) and shortest doubling time (43.08 D°)occurred at 15.6°C. Physiological time was found to be much more realistic in describing population dynamics of this species than was calendar time.
TL;DR: Economic injury levels for the leaffolder Cnaphalocrosis medinalis Guenee on rice variety IR36 were determined as based on percentage of leaves damaged and on number of larvae per plant and indirectly estimated based on larval density by measuring the yield loss at different levels of artificial defoliation.
Abstract: Economic injury levels for the leaffolder Cnaphalocrosis medinalis Guenee on rice variety IR36 were determined as based on percentage of leaves damaged and on number of larvae per plant. The economic injury level based on larval density was indirectly estimated by measuring the yield loss at different levels of artificial defoliation and determining the number of larvae per plant required to cause a given percentage of defoliation. The established economic injury levels at the heading stage were 4.2% damaged leaves and 1.3 larva per plant.
TL;DR: Clerids were the single exception, taking a greater proportion of beetles in endemic infestations, thus suggesting a role by clerids in keeping mountain pine beetle populations at an endemic level.
Abstract: Populations of mountain pine beetles, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), in lodgepole pine, Pinus contorta var. latifolia Engelmann, were sampled at three heights within trees in endemic, epidemic, and postepidemic infestations. Eight mortality factors were evaluated: competition within and between broods, parasites, predators, pathogens, winter temperature, drying of the phloem, pitch, and unexplained mortality. Beetle survival was significantly greater ( P 0.05) by height in trees. Parasites and predators accounted for 8, 33, and 4% of total mountain pine beetle losses in endemic, epidemic, and postepidemic infestations, respectively. Medetera (13%) and woodpeckers (15%) accounted for the greatest amount of predation, and this occurred during epidemic infestations. Most parasites and predators showed the typical density-dependent response. Clerids were the single exception, taking a greater proportion of beetles in endemic infestations, thus suggesting a role by clerids in keeping mountain pine beetle populations at an endemic level. However, clerids accounted for only 0.9% of beetle losses.
TL;DR: Investigating the effect of constant temperature, fluctuating temperature, relative humidity, and photophase on Trichogramma pretiosum Riley developmental time, longevity, fecundity, and sex ratio found the optimal developmental rate occurred at approximately 30°C for all life stages.
Abstract: We investigated the effect of constant temperature, fluctuating temperature, relative humidity, and photophase on Trichogramma pretiosum Riley developmental time, longevity, fecundity, and sex ratio. Equations describing developmental time were derived for all life stages using second-degree polynomials. The optimal developmental rate occurred at approximately 30°C for all life stages. Developmental thresholds for egg, larval, prepupal, and pupal stages, and for development from oviposition to adult, were 13.3, 10.3, 10.7, 13.7, and 13.1°C, respectively. Adult longevity was approximately 2 days under constant temperatures, with the exception of 17 and 35°C (7.67 and 0.60 days, respectively). Fecundity under constant temperature was 18.0 ova per female below 30°C and 9.0 ova per female above 30°C. Parasite sex ratios (male:female) were 1:1, 1:1, 1:2, 1:3, 1:4, and 1:5 for host eggs containing 1, 2, 3, 4, 5, and 6 parasites, respectively. Median developmental time was affected only when the temperature fluctuated between 22 and 38°C. Fecundity and longevity were not significantly affected by the fluctuating temperatures included in the study. Developmental time at 20% RH was approximately 2 days longer than at 60 and 80% RH. Adult female longevity was also significantly longer at 20% RH. However, fecundity was significantly greater at 80% RH. Developmental time was increased under a 12 and 16 h photophase. Female longevity was significantly shorter under a 12 h photophase. Fecundity was unaffected by photophase.
TL;DR: Developmental thresholds and population statistics for A. pisum in Wisconsin were similar to an Ontario (Canada) population established in a climate similar to Wisconsin's, but were dissimilar to a British Columbia populationestablished in a warm, arid region.
Abstract: The relationship between temperature and nymphal developmental rate for Wisconsin populations of the pea aphid, Acyrthosiphon pisum (Harris), was studied in the laboratory and the field. Laboratory studies provided estimates of both lower (2.73°C) and upper (26.02°C) thresholds for development. Age-specific life table parameters were also estimated for two apterous cohorts and one alate cohort exposed to field temperatures. Population growth statistics varied with rearing temperature but, for apterous cohorts, converged when a physiological time scale (“instar periods”) was used. Although stable stage (instar) distributions for the apterous cohorts varied on a physiological time scale, ca. 50% of the individuals in each cohort were first instars, whereas adults accounted for only 7.6 to 13.1% of the total population. Developmental thresholds and population statistics for A. pisum in Wisconsin were similar to an Ontario (Canada) population established in a climate similar to Wisconsin's, but were dissimilar to a British Columbia population established in a warm, arid region. The relevance of these results to the study of A. pisum population dynamics in the field is discussed.
TL;DR: A model is presented which estimates the humidity within the leaf boundary layer, as long as the leaf temperature, ambient temperature, and ambient humidity are known.
Abstract: The humidity of the microhabitat of leaf-inhabiting arthropods can vary greatly with respect to atmospheric humidity. Any models or assumptions made about the impact of atmospheric humidity on these arthropods need to take into account the humidity within the leaf boundary layer. We present a model which estimates the humidity within the leaf boundary layer, as long as the leaf temperature, ambient temperature, and ambient humidity are known.
TL;DR: Low oviposition rate and fecundity at 15°C indicated that this temperature was near the threshold of activity for the adult in Liriomyza trifolii.
Abstract: The development times of the immature stages, oviposition rate, and fecundity were determined for Liriomyza trifolii (Burgess) on celery at 35, 30, 25, 20, and 15°C. Regression equations relating temperature ( X ) to development rates ( Y ) for the egg, larval, and pupal stages were Y = 3.43X − 44.11 (25, 20, and 15°C), Y = 0.70X − 5.87 (35, 30, 25, 20, and 15°C), and Y = 0.76X − 7.79 (30, 25, 20, and 15°C), respectively. Pupal survival was very low (9.4%) at 35°C as compared with the lower temperatures (≥80%). Maximum oviposition rate (38.67 eggs per female per day) and fecundity (405.67 eggs per female) were attained at 30°C. Low oviposition rate and fecundity at 15°C indicated that this temperature was near the threshold of activity for the adult.
TL;DR: A strain of Trichogramma minutum Riley collected from codling moth (CM) Cydia pomonella (L.) in southern Ontario was studied to assess its potential as a biological control agent for that species.
Abstract: A strain of Trichogramma minutum Riley collected from codling moth (CM) Cydia pomonella (L.) in southern Ontario was studied to assess its potential as a biological control agent for that species. The threshold temperature and degree-days (°D) far development were found ta be 128°D10.2 Feeding the wasps diluted honey increased fecundity 6-fold and longevity 9-fald aver unfed wasps. Unmated females lived longer than the mated females but their fecundities were not significantly different. Longevity and fecundity at 25°C were 25.5 days and 236.8 eggs per female. Longevity varied inversely, while daily fecundity varied directly with temperatures between 15 and 35°C. At 35°C, however, fecundity decreased considerably, signifying an adverse effect of high temperature. T. minutum preferred eggs of CM and ariental fruit moth, Grapholitha molesta (Busck), to those of Mediterranean flour moth (MFM), Anagasta kuehniella (Zeller), and oblique-banded leaf-roller, Choristoneura rosaceana Harris, even though they had been reared on MFM eggs for about 22 generations. Parasitism of CM eggs depended on the age of the eggs and density of the parasitoid. Residues af the insecticides permethrin and phosmet on apple leaves significantly lowered rates of parasitization by T. minutum on eggs of CM far mare than 16 days. Residues af azinphosmethyl and phosalone, however, were virtually nontoxic 16 days after application.
TL;DR: Results demonstrate that flowering weeds associated with reduced tillage in corn are beneficial to M. rubens as nectar sources.
Abstract: Laboratory studies investigated the effects of weeds associated with reduced tillage in corn on a major black cutworm parasitoid, Meteorus rubens . Adult female wasps provided with any of five flowering weed species lived longer, attacked more hosts, and produced more offspring than those lacking a food source. In addition, wasps maintained on a combination of three weed species in flower lived longer than those given nonflowering plants of the same species or no food source. These results demonstrate that flowering weeds associated with reduced tillage in corn are beneficial to M. rubens as nectar sources.
TL;DR: Ground faunal predators including Forficulidae, Nabidae, Lygaeidae, and Phalangiidae helped to slow aphid population growth during this period and Sage-chaparral and pear orchard habitats produced primarily ineffective apple aphid predators.
Abstract: Thirty-nine predators and two parasitoids were found attacking apple aphid, Aphis pomi DeGeer, in north-central Washington. Exclusion-cage experiments were conducted to determine the effectiveness of natural enemies. Early-spring control depended on aphidiid parasitoids which killed but failed to complete development in A. pomi . Poor synchrony between A. pomi and its major predators in most years resulted in a month-long “predator gap” allowing rapid aphid colony growth in June. Ground faunal predators including Forficulidae, Nabidae, Lygaeidae, and Phalangiidae helped to slow aphid population growth during this period. Terminal bud set usually occurred in July on mature trees, greatly reducing aphid populations, but young trees sometimes continued growing, allowing buildup of large aphid populations. These were preyed upon by large numbers of Coccinellidae, Chrysopidae, Miridae, Syrphidae, and Chamaemyiidae, which provided control of varying effectiveness. Important sources of effective apple aphid predators were peach orchards, riparian trees and shrubs, some urban ornamental plants, and weeds. Sage-chaparral and pear orchard habitats produced primarily ineffective apple aphid predators. Field feeding trials in single-leaf cages were used to estimate feeding rates of most of the predators.
TL;DR: The results suggest that the use of parasitoids to suppress both fruit fly species might be effective and ecologically acceptable.
Abstract: The Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and the oriental fruit fly, Dacus dorsalis Hendel, and their associated parasitoids were monitored on untreated fruits from mostly deciduous trees grown in the Kula area of Maui, Hawaii, from 1978 through 1981. Biosteres oophilus Fullaway, an egg-larval parasitoid, was predominant and accounted for ca. 80% of the total parasitization. On occasion, parasitization of 32 and 8% was reached by the larval-pupal parasitoids B. longicaudatus Ashmead and B. tryoni Cameron, respectively. These results suggest that the use of parasitoids to suppress both fruit fly species might be effective and ecologically acceptable.
TL;DR: Curculio caryae larvae exposed to Beauveria bassiana or Metarhizium anisopliae were held in soil cages for 14 months and formed colonies up to 8.55 cm in diameter and threatened adjacent weevil larvae 90 to 120 days after primary larvae were infected.
Abstract: Curculio caryae larvae exposed to Beauveria bassiana or Metarhizium anisopliae were held in soil cages for 14 months. After weevil larvae were colonized by B. bassiana, hyphae from the weevil cadavers spread through the surrounding soil and formed colonies up to 8.55 cm in diameter (soil volume, 327.26 cm3). M. anisopliae colonies were restricted to larval cadavers and to the inside of larval soil cells. Adjacent, untreated weevil larvae were sometimes infected and killed by B. bassiana that spread through the soil. B. bassiana colonies reached maximum diameter and threatened adjacent weevil larvae 90 to 120 days after primary larvae were infected.
TL;DR: Rates of parasitism of the eggs of the codling moth, Cydia pomonella, and intra- and intertree dispersal of Trichogramma spp.
Abstract: Rates of parasitism of the eggs of the codling moth, Cydia pomonella (L.), and intra- and intertree dispersal of Trichogramma spp. were studied in an apple orchard after inundative releases of the parasitoid. During the first 2 days after release, dispersal of Trichogramma minutum from tree to tree was affected by prevailing winds. The rate of parasitism was higher in the trees downwind from the release point than in other trees. Vertical and horizontal dispersal within a tree by Trichogramma pretiosum Riley was even in all directions and was not affected by wind direction. The vertical and horizontal distribution of T. minutum within the release trees also was even in all directions; however, the vertical distribution of T. minutum within the trees adjacent to the release site was skewed toward the lower part of the tree canopy. Rain and low temperatures reduced the overall rate of parasitism of C. pomonella by T. minutum.
TL;DR: Hatching of red turnip beetle eggs was studied at 13 constant temperatures, indicating a broad optimal temperature range, and an asymmetrical normal function satisfied the criteria better than the other equations and accurately described the effect of constant temperature on hatching rate.
Abstract: Hatching of red turnip beetle, Entomoscelis americana Brown, eggs was studied at 13 constant temperatures (5–38.5°C). An average of 90% of the fertile eggs hatched from 10 to 36.5°C, indicating a broad optimal temperature range. The lower threshold and upper limit were near 5 and 38.5°C, respectively. The hatching rate (100 per mean no. h until hatching) was calculated for each temperature, and curves were fitted to the data using eight published equations describing the effect of constant temperatures on developmental rates of various insects. Five criteria are presented and used to evaluate the equations. An asymmetrical normal function satisfied the criteria better than the other equations and accurately described the effect of constant temperature on hatching rate for E. americana. Based on this equation, the maximum hatching rate was estimated to be 5.39% per h ± 0.15 (95% confidence interval) at the optimum temperature, 33.4 ± 0.58°C.
TL;DR: Densities of eggs and larvae of the Colorado potato beetle were monitored in an unrotated field of cv.
Abstract: Densities of eggs and larvae of the Colorado potato beetle ( Leptinotarsa decemlineata ) were monitored in an unrotated field of cv. Superior potatoes and one that was rotated with winter wheat. Oviposition and first appearance of larvae were substantially delayed in the rotated field. This delay was attributed to physical and environmental barriers that slow emigration from wheat by overwintering adults.
TL;DR: Standardization of trap position by direct manipulation and covariate analysis were used as techniques for evaluating the comparative effectiveness of five types of traps for apple maggot flies, Rhagoletis pomonella, in commercial orchards in Massachusetts to support a hypothesis that an optimal position exists that maximizes capture.
Abstract: Standardization of trap position by direct manipulation and covariate analysis were used as techniques for evaluating the comparative effectiveness of five types of traps for apple maggot flies, Rhagoletis pomonella (Walsh), in commercial orchards in Massachusetts. Unbaited, 8.5-cm-diameter, dark-red, wooden, sticky-coated spheres caught more of the flies than either baited or unbaited, yellow, sticky-coated rectangle traps (with or without an 8.5-cm-diameter, dark-red disk painted at the center). Evaluation of various positions for sphere traps within apple trees supported a hypothesis that an optimal position exists that maximizes capture. This position is one in which a radius of 0.25 to 0.5 m about the trap is clear of foliage or fruit.
TL;DR: Male Anastrepha suspensa (Loew) produce two female-directed sounds, the calling and precopulatory songs, which compared in males that copulated and males that failed to mate.
Abstract: Male Anastrepha suspensa (Loew) produce two female-directed sounds, the calling and precopulatory songs Aspects of these were correlated to factors thought important in male sexual success and compared in males that copulated and males that failed to mate Both sounds became more intense with male size Larger males tended to have calling songs of lower fundamental frequency, but frequency of precopulatory songs and size was uncorrelated The calling song's fundamental frequency bandwidth was broader in unsuccessful flies, perhaps reflecting physical disability Precopulatory songsmay be the last acoustic opportunity for males to demonstrate their “quality” and receive further cooperation from females they have mounted Unsuccessful precopulatory songs were not as loud and had a broader bandwidth than successful songs Greater distortion in unsuccessful songs appeared to be due to female movement during rejection The longer a precopulatory song, the shorter the subsequent mating This may have been due to males making greater efforts toward less sexually responsive mates Larger males coupled longer, suggesting a potential conflict of interest between the sexes over copulation duration that bigger males are more apt to win
TL;DR: Aphytis melinus DeBach responded significantly more to green and yellow traps than to white, blue, fluorescent yellow, clear, black, or red; Scirtothrlps citri (Moulton) responded significantlyMore to fluorescentyellow, than to any of the other colored polyvinyl rectangular traps.
Abstract: Aphytis melinus DeBach responded significantly more to green and yellow traps than to white, blue, fluorescent yellow, clear, black, or red; Scirtothrlps citri (Moulton) responded significantly more to fluorescent yellow, than to any of the other colored polyvinyl rectangular traps. A. melinus did not distinguish between opaque and translucent colored rectangles nor between different trap shapes. S. citri responded significantly more to translucent yellow and green than to opaque yellow and green. S. citri also preferred triangular, elliptical, and rectangular shapes over circular and square ones. Smaller traps were significantly more efficient in trapping A. melinus than the 386.1-cm2 rectangular traps; however, there was no significant difference between S. citri catches on the basis of number per unit area.