Nymphal Growth Research Articles

Short Communication: Influence of Photoperiod on Temporal Mate Signaling Patterns in the Texas Field Cricket, Gryllus texensis

Crickets appear to be entrained to the circadian mechanism in which they are reared (Wiedenmann, 1988; Wiedenmann et al., 1988), and photoperiod influences a variety of cricket behaviors including egg laying (Olvido et al., 1998), induction of embryonic diapause (Shiga and Numata, 1996), egg hatching (Olvido et al., 1998; Itoh and Sumi, 2000), nymphal growth rate (Carriere et al., 1996), and adult wing from (Masaki and Shimizu, 1995). Photoperiod is also known to influence mate signaling in a variety of insect species including calling onset and duration in gypsy moths, Lymantria disar (Webster and Yin, 1997), and calling onset and temporal pattern in Australian common armyworms, Mythimna convecta (Del Socorro, 1997). In crickets, however, the evidence that photoperiod affects acoustic mate signaling is suggestive but not conclusive. Photoperiod influences time spent calling in the house cricket, Acheta domesticus. In an experiment designed to test the effect of a strong electromagnetic field on the circadian singing activity, Shaw et al. (1995) found that control males (unexposed to the electromagnetic field) monitored in total darkness (0L:24D cycle) called significantly more often than males monitored in a more natural light cycle (12L:12D cycle). This research,

Life Cycle and Synchronization of Nymphal Development of the Mayfly Ephoron shigae in Japan (Ephemeroptera: Polymitarcyidae)

The life cycle of E. shigae, including eclosion, nymphal growth, last instar recruitment and adult emergence, was studied in a Japanese river. The synchronization of nymphal development is discussed. Eggs hatched sporadically from mid-March to early April as determined from continuous sampling of eggs from the river substratum. Nymphs attained the last instar in mid- to late August and emerged in mid-September. Size of nymphs at the time of last instar recruitment decreased gradually as did the size of emerging mayflies. Smaller individuals entering the last instar later developed more quickly and required a smaller number of degree-days to complete the last instar than did larger individuals. Consequently, larval development synchronized during the period between last instar recruitment and adult emergence.

Feeding damage by Diuraphis noxia results in a nutritionally enhanced phloem diet

AbstractThe feeding behavior of Diuraphis noxia Mordvilko (Homoptera: Aphididae) on susceptible hosts causes both ultrastructural and tissue level damage which may affect phloem composition. Genetic evidence suggests that endosymbiotic bacteria in most aphids overproduce limiting amino acids to benefit hosts but that D. noxia depends less on endosymbionts for these nutrients, possibly due to an enriched diet. To determine whether D. noxia feeding damage results in higher concentrations of essential amino acids, stylet exudates were analyzed from wheat (Triticum aestivum) damaged to different degrees. Comparison of samples from undamaged and damaged susceptible wheat revealed changes in amino acid composition and an increase in levels of essential amino acids, indicating a nutritionally enhanced ingesta. The changes in stylet exudates paralleled changes in leaf exudates, indicating that the effects are systemic. Feeding damage is not observed on a resistant wheat host, var. Halt, and leaf exudates from infested Halt did not show changes in amino acid composition. Mean relative growth of nymphs was significantly lower on Halt than on susceptible Arapahoe, indicating that Halt is a less suitable host. Both varieties show similar amino acid levels in non‐infested samples, suggesting that D. noxia infestation does not enhance the phloem environment in Halt. This study provides evidence that aphid feeding can generate a nutritionally enhanced phloem diet.

EVALUATION OF SODIC SOIL TOLERANT RICE CULTURES AGAINST MAJOR PESTS IN TRICHY

Four sodic soil tolerant rice cultures received from the International Rice Research Institute (IRRI), Philippines were evaluated for their host-plant resistance to brown planthopper. Nilaparvata lugens in screen house and leafholder, Chaphalorrocis medinalis and yellow stem borer. Scirpophaga incertulas under field conditions. The level of antixenosis and antibiosis mechanisins found in the four cultures viz., IRRI 2011, 2028, 2030. 2122 were measured in comparison with the local check CO43. In seedling box screening test, all the cultures showed lower damage rating and nymphal settling response against the check. Further, the cultures delayed the nymphal growth (13.60 16.20 days) compared with CO 43 (13.0 days). Similarly, low fecundity (136.0-163.0 nos) ad shortened female adult longevity (6.09.60 days) were recorded on sodic soil tolerant cultures than CO43 (203.0 nos. and 12.4 days). Significant differences were observet among the test cultures/variety in the nymphal survival rate and their emergence. In the field, the culture IRRI 2028 was found to be highly susceptible to both pests.

Effects of Nutrition on Longevity, Fertility, Ovariol Yield, Food Consumption and Metamorphosis of the Grasshopper Euprepocnemis plorans

Effects of adult nutrition were investigated by measuring female longevity, body weight, fertility and ovariol yield in the grasshopper, Euprepocnemis plorans reared on 3 different host plants. Rearing the insect on lupine (Lupinus termis) and horsebean (Vicia faba) caused significant reduction in fertility and ovariol yield of its first and second pods compared with those reared on clover (Trifolium alexandrinum). Resorption bodies were significantly higher in the ovariols of females fed on L. termis and V. faba. Diet also affected longevity and body weight. Fecundity was highest in females reared on T. alexandrinum. Significant reduction in haemolymph protein was noted in females reared on L. termis and V. faba. Nitrile (allylcyanide) significantly reduced the approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD), inhibited nymphal growth, increased food consumption and decreased its assimilation. Feeding grasshoppers on T. alexandrinum treated with 125–250 μ mole/g resulted in various degrees of malformation and death.

Identification of Resistance to Azalea Lace Bug among Deciduous Azalea Taxa

The susceptibility of seventeen deciduous species or cultivars and one evergreen cultivar of azalea (Rhododendron spp.) to azalea lace bug (Stephanitis pyrioides Scott) was evaluated in field and laboratory experiments. Rhododendron canescens Michx. and R. periclymenoides (Michx.) Shinners were the most resistant species, followed by R. prunifolium (Small) Millais. Ratings were based on oviposition rate, percentage emergence from the egg, feeding damage, and nymphal growth rate. The most susceptible genotypes were TNLV1, R. oblongifolium (Small) Millais, R. alabamense Rehder, R. serrulatum (Small) Millais, R. viscosum (L.) Torr., `Buttercup', and `My Mary'. Leaf water content and leaf pubescence were significantly different among taxa. However, leaf water content was not significantly correlated with azalea lace bug performance, and insufficient evidence was available to conclude that leaf pubescence was involved in azalea lace bug resistance.

Field observations of dispersion, mating and development of Amorbus obscuricornis (Westwood) (Hemiptera: Coreidae)

Aspects of the behaviour and development of Amorbusobscuricornis were observed in the field during spring and summer 1994/1995 at a site in southern Tasmania. Nymphs of A. obscuricornis remained predominantly on host plants on which they were initially observed for much of their development. Some movements between hosts occurred with migrating nymphs ranging in age from second to fourth instar. Most adults observed for the first time on hosts were males, a number of which were later recorded with females. Males were observed to have longer host residence times (7–56 days) than females (≤ 7 days). Complete nymphal development was roughly estimated to take considerably fewer degree‐days under fluctuating field temperatures than at constant temperature. This suggested that other mechanisms (e.g. basking) may significantly influence nymphal growth and development.

EFFECTS OF RAPE GROWN IN SO2‐ENRICHED ATMOSPHERES ON PERFORMANCE OF THE APHID, MYZUS PERSICAE (SULZER) *

Abstract Performances of the aphid, Myzus persicae, were monitored during feeding on leaves of the rape, Brassica chinensis, previously fumigated with SO2 in a range of concentrations between 20 and 160 nl/1 at 25°C. Response of the aphids depended on dose of the air pollutant. Moderate dose of SO2 treatment on the rape greatly enhanced the aphids' performances while high level of the pollutant heavily suppressed their growth and reproduction. They performed best at about 80 nl/l SO2, where nymphal mean relative growth rate (MRGR), adult fecundity and intrinsic increase rate(rm) of the population increased by 31.5%, 89.8% and 42. 7% over those of control aphids, respectively. Determination of the plant chemistry suggests that the altered relative content of methionine induced by So, exposure might be responsible for this response of dosage dependence.

Allelochemicals in Tomato Leaves Affect a Specialist Insect Herbivore Manduca sexta Negatively but with No Ill Effects on a Generalist Insect Predator, Podisus maculiventris

To understand the role of allelochemicals in tritrophic interactions, it is important to consider how allelochemicals affect both insect herbivores and their predators. In one experiment, a specialist insect herbivore (Manduca sexta: Sphingidae) was fed artificial diet either without allelochemicals, or containing a combination of allelochemicals found in tomato leaves (tomatine, rutin and chlorogenic acid). When fed artificial diet containing allelochemicals, the herbivores consumed less food, their developmental time was extended and their final weight was lower than those fed artificial diet without allelochemicals added. In another experiment, a generalist insect predator (Podisus maculiventris: Pentatomidae) was given prey (M. sexta) fed artificial diet either without allelochemicals, or with the combination of allelochemicals. The allelochemicals in prey diet did not affect nymphal growth, nymphal survivorship, adult female longevity, number of eggs produced, number of egg masses produced, developmental period of the eggs, viability of the eggs, or weight of the first instar progeny. Thus, this study documents a case in which a plant would benefit by producing allelochemicals because the specialist herbivore would consume less plant material and by ingesting the allelochemicals have poorer growth, and the predator would be unharmed by the presence of allelochemicals within the diet of its prey.

Detection and quantification of a very high density lipoprotein in different tissues of Triatoma infestans during the last nymphal and adult stages

The presence of a very high density lipoprotein (VHDL), an hexameric protein, was explored in different tissues of Triatoma infestans throughout the last nymphal and adult stages, and in egg extracts by Western blot assays. The VHDL was always detected in both, hemolymph and fat body, during the above mentioned stages and it was also observed in the buffer soluble fraction of testis and egg homogenates. An enzyme-linked immunosorbent assay (ELISA) was used to measure the VHDL titer in these tissues. Hemolymph VHDL reaches a maximum value before the last molt, then it abruptly declines in males and females just after emergence, but during adult life it increases again. Fat body VHDL decreases slowly and continuously during the nymph growth reaching a minimum value prior to molting, and in the first week of adult life the values were even two-fold lower; then, it shows a different cycle of accumulation and depletion in males and females. In adult testis the VHDL undergoes a cycle similar to the one observed in male fat body. This protein increases progressively during embryonic development and, at the time of larval hatching it reaches its maximum value. The hexameric protein presents homologies in its N-terminal sequence with storage hexamerins of Diptera, Lepidoptera and Hymenoptera.

Life History Attributes of the Rare Mayfly Siphlonisca aerodromia Needham (Ephemeroptera:Siphlonuridae)

Over a 3-y period, we examined the biology of late-instar nymphs, adults, and eggs of the rate predaceous mayfly S. aerodromia at Tomah Stream, Maine, to identify life history attributes associated with the mayfly's movements between the stream channel and the bordering floodplain. Eggs were deposited in the stream channel in June and hatched in November and December. Embryonic development occurred in 47-92% of eggs from unmated females. With rising water levels following snowmelt in March or April, nymphs moved from channel to floodplain, where most nymphal growth and development took place. Sex ratios of nymphs in the floodplain were female biased (1 M:1.4 F in 1991 and 1 M:2.1 F in 1992). Nymphs molted to the final instar earlier in 1991 than in 1992 and male nymphs molted to the final instar before female nymphs in 1991 but not 1992. Time in the final instar decreased as the season advanced. Seasonal emergence was protandrous and lasted 10-11 d during late May and early June; timing of seasonal emerge...

Resource partitioning to growth, storage and defence in nitrogen-fertilized Scots pine and susceptibility of the seedlings to the tarnished plant bug Lygus rugulipennis.

We tested how variable nitrogen availability affects the above-and below-ground growth of first-year Scots pine (Pinus sylvestris L.) seedlings and carbon allocation to defensive allelochemicals and storage. Concentrations of free ammo acids were considered as indicators of nutritive quality. Suitability of seedlings for polyphagous Lygus rugulipennis Popp. (Heteroptera: Miridae) was tested with oviposition preference and nymphal growth experiments. At the end of the growing season, needle length increased while root hiomass decreased with elevated N fertilization, but shoot length was not affected. Concentration of starch in needles and roots, representing carbon storage, was not significantly affected by N fertilization, although there was a decrease in the starch concentration of needles when nitrogen input increased. Nitrogen fertilization significantly increased the pool of total and non-essential ammo acids in the shoots. Arginine, proline and glutamine were the individual ammo acids most affected by elevated N. Of the carbon-based defence compounds, total resin acid concentrations in shoots were significantly reduced with elevated nitrogen in 9-wk-old seedlings. Palustric acid and neoabietic acid were the most affected individual) resin acids, where as foliar monoterpenes were not influenced by N availability. Total phenolics in shoot and root showed variable response. The increasing effect of nitrogen on the oviposition rate of Lygus females was almost linear. Mean relative growth rate of the nymphs was significantly affected by the level of N fertilization. but the mortality of nymphs was high in all treatments. The results suggest that in nitrogen-rich environments the needle growth of small Scots pine seedlings is improved, but their Susceptibility to insect attack is increased and they remain less defended as predicted by the carbon/nutrient balance hypothesis. Total phenolics and resin acids, representing phenylalanine and mevalonic acid pathways, respectively, were both reduced by increased nitrogen availability. Together with the simultaneous increase of foliar free nitrogen in the form amino acids, the nutritive value of seedlings is ameliorated and this might explain susceptibility of nursery-grown. N fertilized seedlings to polyphagous Lygus bugs.

Life history plasticity of Nemoura trispinosa (Plecoptera: Nemouridae) along a permanent‐temporary water habitat gradient

SUMMARY1. The life history of the small herbivorous stonefly Nemoura trispinosa Claassen was studied in a variety of small springs in southern Ontario, Canada. Nymphs generally were able to tolerate a wide range of environmental conditions and were found in 78% of habitats sampled, although population densities differed markedly.2. Life‐cycle patterns varied from a univoltine, slow seasonal type to a univoltine, fast seasonal type with extended egg development. In one, highly stable, spring the life cycle was semivoltine. Inter‐year variation was studied for 5 years in one spring and was found to be low relative to among‐spring variation.3. Differences in the life history traits of N. trispinosa populations from our spring series were most probably an expression of phenotypic plasticity rather than of genetic differentiation.4. Maximum annual water temperature was the factor most influential on nymphal growth rate (non‐linear relationship), whereas range in generation time was related to the degree of habitat permanence.

Numerical allometric growth of the ommatidia, antennal sensilla, and teeth of foretibial combs in the milkweed bug Oncopeltus fasciatus Dallas (Heteroptera : Lygaeidae)

Oncopeltus fasciatus (Heteroptera : Lygaeidae), the milkweed bug, was bred in captivity. Sampling showed that individuals grow exponentially through their 6 developmental stages with an average linear increase per molt of 42% for the females and 41% for the males. The number of ommatidia per eye grows with negative allometry from an average of 30 in the first instar to 860 in the male and 820 in the female adult. The total number of sensilla on the 2 flagellar segments of an antenna increases with negative allometry during the 5 nymphal stages from a mean of 239 in the first instar to 2462 in the last. At this point, this allometric growth pattern is sharply broken by distinct numerical increase to 7163 on the adult flagellum. The number of teeth composing the foretibial comb, the tool for grooming the distal flagellar segment, grows with negative allometry through all 6 developmental stages. Calculations using previously published data from the migratory locust, Locusta migratoria, revealed the same growth pattern of antennal sensilla: uniform allometric growth during the nymphal development, broken by a conspicuous upward jump to the adult number of sensilla. In the American cockroach, Periplaneta americana, this growth pattern of antennal sensilla holds only for the male; the female continues the nymphal allometric growth into the adult stage. These observations on allometric growth fit three theoretical explanations: 1. Smooth allometric growth is evidence for an aut-adaptation to increasing size. 2. Ex-adaptations to novel ecological niches cause breaks in allometric growth patterns. 3. Chapman's rule, which states that increased mobility correlates with greater olfactory sensitivity, correctly predicts the observed breaks in the allometric growth patterns in the abundance of antennal sensilla.

Development and reproductive potential of the cereal aphid Sitobion avenae on resistant wheat lines (Triticum monococcum)

SummaryThe effect of wheat resistance in lines of Triticum monococcum L., on the reproductive performances of the cereal aphid (Sitobion avenae F.) was investigated. Aphids were reared from birth to adult moult either on resistant or susceptible wheat lines, and transferred as apterae to both host genotypes. The influence of these transfers on the subsequent adult weight, gonad status and reproductive performances was evaluated.Aphids transferred from resistant to susceptible plants proved able to compensate for their poor nymphal growth, mainly through additional embryo growth and an increase in the number of matured embryos within the first 10 days of their adult life. Most aphids transferred from susceptible to resistant plants died within the first week following the transfer. Their most advanced embryos matured and were born, but subsequent embryo growth was quickly reduced.The reproductive strategies adopted by S. avenae when facing plant resistance, and the hypothesis of a resistant mechanism based on a poor nutritional state of the resistant plants are discussed.

Effects of Stationary Photoperiod on Diapause Induction of Eysarcoris lewisi DISTANT(Heteroptera:Pentatomidae)and the Developmental Stage Sensitive to Stimulus for Reproductive Diapause

The critical photoperiod for reproductive diapause in Eysarcoris lewisi DISTANT was between 15L-9D and 15.5L-8.5D. The 5th instar and the adult stages were sensitive to photoperiod, a stimulus for reproductive diapause. When the bugs were reared under 16L-8D during the nymphal period and then were switched to 12L-12D in the adult stage, no females laid eggs. The preoviposition period of females which experienced 12L-12D at least in the 5th instar was longer than that of the females which experienced 16L-8D. The 3rd instar was a stage sensitive to photoperiod which was a stimulus for nymphal growth; the nymphs reared under 12L-12D in the 3rd instar grew more quickly in the following 4th and/or the 5th instars than those under 16L-8D in the 3rd instar.

Biology of Macropanesthia rhinoceros Saussure (Dictyoptera: Blaberidae)

Field and laboratory observations of Macropanesthia rhinoceros Saussure were undertaken. These cockroaches live in permanent underground burrows and feed on dry leaves and twigs. M. rhinoceros are usually found alone; however, young nymphs remain with their mother for some months and adult males may cohabit with late-instar female nymphs. One brood of ≈20 young is produced each year in late spring after an incubation period lasting ≈3 mo. Nymphal growth is variable and is slower in the laboratory than in the field. Field nymphs reach the eighth instar in ≈5 mo. There are 11-14 nymphal instars and the shortest nymphal period is <3 yr. Adults can survive in the laboratory for 7 yr. After rain, cockroaches may be observed on the soil surface. Adult males are more prevalent than females. Typically, males wander searching for mates while females take litter into their burrows. General aggressiveness of individuals is consistent with a solitary existence. Adult males are highly aggressive towards one another. Females with young are more aggressive than those without young. Courtship behavior is relatively simple and comparable to other cockroaches that live in restrictive habitats.

Life cycles of 12 species of winter stoneflies from Quebec (Plecoptera; Capniidae and Taeniopterygidae)

The life cycles of 12 species of winter stoneflies belonging to the families Capniidae and Taeniopterygidae were studied in six river systems (seven sampling sites) in southern Quebec. Eight of the cycles were previously undescribed. All species were univoltine. Adults emerged as soon as the ice broke on the streams in late winter, except for Paracapnia angulata, Taenionema atlanticum, and Strophopteryx fasciata, which emerged about 3 weeks later. The simplest cycle occurred in Paracapnia opis, and P. angulata: egg development was direct and nymphal growth proceeded steadily from May to January. All other species showed evidence of a nymphal diapause interrupting development between June and September. In Allocapnia pygmaea, A. recta, C. vernalis, Taeniopteryx maura, T. parvula, and Oemopteryx glacialis, growth was completed by January, but A. minima, A. maria, Taenionema atlanticum, and Strophopteryx fasciata continued to develop through the winter and reached maturity just before emergence. Allocapnia recta, the first species to emerge, was also the first to mature, but the population showed much variability and the last nymphs to emerge were probably the only ones to survive and reproduce under Quebec climatic conditions.

Forests and the temperature of upland streams in Wales: a modelling exploration of the biological effects

SUMMARY. 1. Daily temperature data from six streams in upland Wales were used to explore the thermal effects of afforestation on stream ecology. The data were linked to published biological models to simulate fish and invertebrate development.2. Mean daily temperatures in forest streams were lower than those of moorland streams in spring and summer, and higher in winter. These spatial comparisons were supported by the results of experimental bank‐side clearance at a forest site, where there was evidence that stream temperatures fell in winter and rose in spring following treatment.3. Simulations indicated that brown trout (Salmo trutta) could weigh over 30% more by the end of their second growing season in a moorland compared with a forest stream. Several species of insects showed slower simulated egg development at forest sites. For two ephemeropteran species simulated nymphal growth was also retarded, suggesting significant alterations to the life cycle. Two plecopteran species were affected only slightly by the different temperature regimes.4. Overall, the simulations suggested that afforestation, by reducing summer temperatures, could lead to marked reductions in rates of development of some invertebrates and fish.

Nymphal Development and Adult Longevity of the Australian Wood-Feeding Cockroach Panesthia cribrata (Dictyoptera: Blaberidae)

Nymphal development and adult longevity were examined in three populations of the Australian wood-feeding cockroach Panesthia cribrata Saussure. The sizes of nymphs and the rates of increase in size between molts were found to vary greatly between individuals, broods, and populations. Evidence of polymorphism was observed in all populations. Nymphal development was calculated for two populations from field and laboratory data. In one, development was estimated to take at least 6 yr and encompass 12 instars. For the other population, the respective estimates were at least 4 yr and 9 instars. Adult longevity was calculated to exceed 4 yr. The characteristic patterns of growth of nymphs from each population were found to be relatively constant, even when all specimens were cultured under identical laboratory conditions.