Dispersal Capacity and Behavior of Nymphal Stages of Halyomorpha halys (Hemiptera: Pentatomidae) Evaluated Under Laboratory and Field Conditions

The invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a highly polyphagous and mobile pest causing crop damage aggregated at the perimeters of crop fields. Understanding the dispersal biology of H. halys is critical for the development of reliable monitoring and management strategies. In this study, dispersal ecology of H. halys nymphs was studied under laboratory and field conditions. In the laboratory, horizontal and vertical walking capacity was quantified for mobile nymphal stages (i.e., 2nd through 5th instars) and compared with adults. There was a significant difference in the horizontal distance moved by H. halys among the life stages tested. Third instars exhibited significantly greater walking distances compared with adults; horizontal walking distances by other nymphal stages were not significantly different from adults. A similar pattern was observed from vertical climbing tests of H. halys. Third and 4th instars climbed significantly greater distances compared with 2nd instars and adults, while distances climbed by 5th instars were intermediate. In the field, the walking distance of 3rd and 5th instar nymphs on mowed grass was quantified based on direct observation of individuals for 30 min. Under these conditions, 5th instars moved nearly two-fold greater distances compared with 3rd instars, but surface temperature affected both nymphal stages similarly. Shorter bouts of movement were common at surface temperatures below 25 °C, whereas individuals showed longer walking distances above 25 °C. In mark-release-recapture studies, 4th and 5th instars were released and recaptured in traps baited with attractive pheromonal-based stimuli to estimate dispersal rates under field conditions. When insects were released 5 m from traps, both instars were first recaptured within 2 h after release, with the recapture rates of 54 and 69 % for 4th and 5th instars over 24 h, respectively. When insects were released 20 m from traps, 4th and 5th instars were first recaptured in less than 5 h, with the recapture rates of 27 and 51 %, respectively. The results of this study indicate that H. halys nymphs have strong dispersal capacity with which populations can easily move among host plants and other attractive stimuli at farmscape levels.     

Temperature affects interaction of visual and vibrational cues in parasitoid host location

Parasitoid host location in nature is facilitated by simultaneously using different information sources. How multisensory orientation on the same spatial scale is influenced by environmental conditions is however poorly understood. Here we test whether changes in reliability of cues can cause parasitoids to alter multisensory orientation and to switch to cues that are more reliable under extreme temperatures. In the ichneumonid wasp Pimpla turionellae, multisensory use of thermally insensitive vision and thermally sensitive mechanosensory host location by vibrational sounding (echolocation on solid substrate) was investigated with choice experiments on plant-stem models under optimum temperature (18°C), at high- (28°C) and low-temperature limits (8°C) of vibrational sounding. Temperature affected relative importance of vibrational sounding whereas visual orientation did not vary. At 18°C, parasitoids used visual and vibrational cues with comparable relative importance. At 8 and 28°C, the role of vibrational sounding in multisensory orientation was significantly reduced in line with decreased reliability. Wasps nearly exclusively chose visual cues at 8°C. The parasitoids switch between cues and sensory systems depending on temperature. As overall precision of ovipositor insertions was not affected by temperature, the parasitoids fully compensate the loss of one cue provided another reliable cue is available on the same spatial scale.     

Riverine life history of the amphidromous goby Sicyopterus japonicus (Gobiidae: Sicydiinae) in the Ota River, Wakayama, Japan

To understand the riverine life history of the amphidromous goby, Sicyopterus japonicus, studies were conducted in the Ota River, Wakayama, Japan. They were distributed from 3 to 23 km upstream from the river mouth, and abundance was higher in the middle reaches than in the upper and lower reaches. Fish were not observed in rapids during winter, suggesting a seasonal change of habitat. Body length ranged from 24 to 120 mm SL. Both females and males ranged from 1 to 6 years old, and males had larger asymptotic length than females. Condition factor showed two peaks in July and November, which appeared to correspond to the spawning season and preparation for over wintering. Gonad somatic index increased in summer with a peak in August indicating a summertime spawning season that was confirmed by collections of the newly hatched larvae migrating downstream. Eggs of 0.5 mm diameter were attached to stones and newly hatched larvae made continuous vertical movements of sinking and upward swimming and the distance of each movement was longer in freshwater than in seawater. The newly hatched larvae were collected at nighttime (19:00–24:00) mainly in August. Those larvae were very small (mean: 1.4 mm TL) with a yolk sac and no eye pigmentation. Low wintertime temperatures are likely an important determinant of the spawning and recruitment seasons and seasonal changes of activity of this species that lives at much higher latitudes than all other species of the subfamily.     

Magnetic Orientation in the Savannah Sparrow

Although magnetic compass orientation has been reported in a number of invertebrate and vertebrate taxa, including about a dozen migratory bird species, magnetic orientation capabilities in animals remain somewhat controversial. We have hand-raised a large number of Savannah sparrows (Passerculus sandwichensis) to study the ontogeny of orientation behavior. Young birds with a variety of early experience with visual and magnetic orientation cues have been tested for magnetic orientation during their first autumn migration. Here we present data from 80 hand-raised sparrows, each tested several times in both normal and shifted magnetic fields. Birds reared indoors with no experience with visual orientation cues showed axial north-south orientation that shifted by almost exactly the magnitude of 90° clockwise and counterclockwise shifts in the direction of magnetic north. Other groups of birds with varying early experience with visual orientation cues showed different preferred orientation directions, but all groups shifted orientation direction in response to shifts in the magnetic field. The data thus demonstrate a robust magnetic orientation ability in this species.     

How Far Stationary Contrast Boundaries Can Be Away to Elicit Behavioral Responses in Praying Mantis

The aim of the present study was to investigate the distance at which vertical black and white stripes (contrast boundaries) elicit object-related behavioral responses in 6th instar and adults of the praying mantis Mantis religiosa. The mantids reacted when the contrast boundaries were not further away than 60 cm. However, with increasing distance (>20 cm), the contrast boundaries became progressively less significant for the mantids. Jumps/preparation of jumps could be observed between 10 and 30 cm. The results are supportive for distance measurement of up to 20–30 cm, which corresponds to distance accessible for the insect. It seems that image motion cues induced by peering movements play an important role.     

Olfactory and visual stimuli affecting host plant detection in Homalodisca coagulata (Hemiptera: Cicadellidae)

The relative effects of visual and olfactory stimuli on host plant detection in immature and adult Homalodisca coagulata Say (Homoptera: Cicadellidae) were studied using a novel olfactometer and factorial experimental designs. Colored, gray, and white cards were used as visual targets. Each card was attached to a glass thistle tube from which host-plant odor (from Vigna unguiculata L.) or blank, humidified air was dispensed. Visual + odor stimuli combinations were presented in no-choice tests. Nymphs were released onto a perch stick downwind from the target. Nymph response to color + odor treatments was measured by the duration of orientation behavior, residence time on the perch, and percentage of individuals that jumped to the target. The assay was modified so that adults crawled from the perch onto the target. Adult response was measured by the duration of individual behaviors (e.g., foraging) and by their position and residence time on the target. Both main effects and interactive effects of the stimuli were observed. Nymphs showed a decrease in orientation and residence times in the colored target + host odor treatments and increased jumping response in the gray + host odor treatment. When adults were exposed to host odor, the duration of foraging behavior increased, whereas crawling and phototactic behaviors decreased. Although nymphs and adults responded to visual stimuli + blank air treatments, host odor enhanced their responses. The primary effect of host odor on host detection behavior may be to enhance H. coagulata responsiveness to visual cues.     

Development times and fecundity of three important arthropod pests of strawberry in the United Kingdom

The development rates and fecundity of three important pests of strawberry in the UK were determined over a range of temperatures. Development time of the strawberry tarsonemid mite, Phytonemus pallidus, from egg lay to adult, ranged from a mean of 28.4 days at 12.5°C to 8.8 days at 25°C. No nymphs developed to adult at 10°C. Females lived for up to 45 days and laid a mean of 24.3 and 28.5 eggs at 20°C and 25°C respectively. Total development time from egg lay to adult for the strawberry blossom weevil, Anthonomus rubi, ranged from a mean of 95.7 days at 10°C to 18.2 days at 25°C. Mean fecundity at 20°C was 157.6 eggs, and the oviposition period averaged 71.6 days. When nymphs were reared on strawberry, development of the European tarnished plant bug, Lygus rugulipennis, from egg lay to adult, ranged from 83.8 days at 15°C to 28.8 days at 25°C. Development times on groundsel were shorter and ranged from 65.6 to 22.2 days at 15°C and 25°C. Only two nymphs developed to adults at 10°C; no eggs hatched at that temperature. Mean fecundity at 20°C was 75.4 eggs, but ranged from 23 to 179. Under a fluctuating temperature regime of 10°C for 12 h:20°C for 12 h, nymphs of L. rugulipennis took 40.3 days to become adult on strawberry, and 33.4 days on groundsel. Simple linear models fitted the developmental rate ‐ constant temperature relationship well for all species, accounting for 95–98% of the total variation in observed developmental rates. Development under fluctuating temperatures illustrated the potential problem of extrapolating linear models beyond the conditions of the experiment.     

Response of the Praying Mantis,Sphodromantis Viridis,to Target Change in Size and to Target Visual Occlusion

Mantises (Mantodea, Mantidae) visually detect insect prey and capture it by a ballistic strike of their specialized forelegs. We tested predatory responses of female mantis, Sphodromantis viridis, to computer generated visual stimuli, to determine the effects of (i) target size and velocity (ii) discrete changes in target size and (iii) visual occlusion. Maximal predatory responses were elicited by stimuli that (i) subtended ~20°–23° horizontally and ~16°–19° vertically, at the eye, and moved across the screen at angular velocities of ~46°–119°/s, (ii) increased in size in a stepwise manner, with step duration ≥0.8 s, while stimuli decreasing in size elicited only peering movements, (iii) Stimuli disappearing gradually behind a virtual occlusion elicited one or more head saccades but not actual interception.     

Cold tolerance of the coconut hispine beetle, <Emphasis Type="Italic">Brontispa longissima</Emphasis> (Coleoptera: Chrysomelidae) in Japan

The coconut hispine beetle, Brontispa longissima (Gestro), supposedly originated from Papua New Guinea and Indonesia but has recently invaded Southeast and East Asian countries where it has been causing serious damage to Cocos nucifera L. This insect also occurs on the Southwest Islands off Kyushu Island in Japan. To evaluate the potential northward range expansion of this insect in Japan, we investigated its cold tolerance at 0, 5, and 10 °C (egg, larva, pupa, and adult), 13 °C (adult), and 15 °C (egg and hatched larva). At 15 °C, few eggs hatched, and the larvae that hatched died within a few days of hatching. At 13 °C, Ltime₉₅ was estimated to be 23 days for adults, with the most cold-tolerant developmental stage at 10 °C. At all developmental stages, Ltime₉₅ of B. longissima was estimated to be 19 days at 10 °C, 8 days at 5 °C, and 5 days at 0 °C, suggesting the cold tolerance of this beetle is very low. Considering average daily temperatures, it is unlikely that B. longissima can establish itself north of Amami-Oshima Island, located in the far south off the main island of Japan.     

Role of chemical and visual cues in food recognition by leatherback posthatchlings (Dermochelys coriacea L)

We raised leatherback posthatchlings in the laboratory for up to 7 weeks to study the role of visual and chemical cues in food recognition and food-seeking behavior. Turtles were reared on a formulated (artificial gelatinous) diet and had no contact with test materials until experiments began. Subjects were presented with visual cues (a plastic jellyfish; white plastic shapes [circle, square, diamond] similar in surface area to the plastic model), chemical cues (homogenates of lion's mane jellyfish, Cyanea capillata; moon jellyfish, Aurelia aurita; and a ctenophore, Ocyropsis sp., introduced through a water filter outflow), and visual and chemical cues presented simultaneously. Visual stimuli evoked an increase in swimming activity, biting, diving, and orientation toward the object. Chemical cues elicited an increase in biting, and orientation into water currents (rheotaxis). When chemical and visual stimuli were combined, turtles ignored currents and oriented toward the visual stimuli. We conclude that both cues are used to search for, and locate, food but that visual cues may be of primary importance. We hypothesize that under natural conditions turtles locate food visually, then, as a consequence of feeding, associate chemical with visual cues. Chemical cues then may function alone as a feeding attractant.     

Guidance by odors in honeybee navigation

Animal navigation is guided by multiple sensory cues. Here, we ask whether and how olfactory stimuli emanating from places other than the trained feeding site redirect the flight paths of honeybees. The flight trajectories of individual bees were registered using harmonic radar tracking. Sensory cues (compass direction, distance, visual cues en route and close to the feeding site) associated with the trained flight route dominated wayfinding, but a learned odorant carried by air flow induced excursions into the wind. These redirections were largely restricted to rather small deviations from the trained route (<60°, <200 m) and occurred only if the animal did not receive the trained odorant stimulus at the trained feeding site. Under certain conditions, larger excursions were observed. These findings are discussed in the context of odor guidance of honeybees over longer distances (>300 m from the hive).     

Life history tactics of southern velvet shrimp Metapenaeopsis palmensis (Crustacea,Decapoda) in the waters off southwestern Taiwan

The southern velvet shrimp, Metapenaeopsis palmensis, a small, tropical r-strategist shrimp, was investigated to test whether its life history tactics are similar to those of penaeid shrimps. In total, 7,832 shrimps were collected in southwestern Taiwan from April 2002 to August 2011. For the first time, we have identified the shrimp as a multiple spawner. This species has a size-segregated distribution, with the newly recruited early juveniles [<6.00 mm carapace length (CL)] living offshore (water depth = 30 m) and the subadults and mature spawning adults (CL ≥9.39 mm) living inshore (water depth = 15–20 m). They spawn from February to June before the rainy season when the water temperature exceeds 25°C. Only the larvae hatched in the late spawning season will successfully recruit in the dry season in September–November when the bottom water salinity is higher than 33.5 psu. The life history tactics of this species are different from those found by various previous studies on penaeid shrimps.     

Orientation and Shape Discrimination in Juveniles and Adults of the Mangrove Crab Aratus pisonii (H. Milne Edwards, 1837): Effect of Predator and Chemical Cues

Behavioral responses of juveniles and adults of the mangrove crab Aratus pisonii (H. Milne Edwards, 1837) to black geometric shapes of equal surface area was measured. Crabs were tested either in presence or absence of chemicals generated from two common predator species, the portunid crab Callinectes ornatus Ordway, and the soapfish Haemulon aurolineatum Cuvier, 1830. The present study tested the hypothesis that A. pisonii (1) has the capacity to orient to visual cues; (2) it discriminates between different visual objects based on a combination of chemical and visual information and (3) this behavior changes with age. When presented with single black targets in background water, juveniles oriented toward all shapes. This behavioral response was interpreted as visual orientation toward potential shelter. Among shapes, juveniles showed preference for the vertical rectangle, probably due to the recognition of natural visual elements like mangrove roots. In predator conditioned water, juveniles exhibited a stronger response than in background water. Thus, juveniles were able to detect by odor the potential presence of predators. Change in responsiveness between adults and juveniles was also demonstrated.     

Identification and virulence characterization of entomopathogenic fungus <Emphasis Type="BoldItalic">Lecanicillium attenuatum</Emphasis> against the pea aphid <Emphasis Type="BoldItalic">Acyrthosiphon pisum</Emphasis> (Hemiptera: Aphididae)

An entomopathogenic fungal strain was originally isolated on artificial medium from the corpse of a pea aphid (Acyrthosiphon pisum Harris) collected at Jingzhou, China (N30°21′18.15″, E112°08′41.63″). Based on tests of the morphological, physiological and biochemical characteristics and analysis of internal transcribed spacer (ITS) sequences, it was considered to be a strain of Lecanicillium attenuatum Zare & W. Gams. Therefore, the strain was designated L. attenuatum YZU 151121. The activity of the biological agents under study was determined at 26 °C and 90% relative humidity. The number of A. pisum killed was increased by increasing the concentration of L. attenuatum. The results demonstrated that L. attenuatum YZU 151121 showed a high efficacy against 3rd-instar nymphs (LC₅₀ = 2.91 ± 0.365 × 10⁵ conidia/ml) and adults (LC₅₀ = 3.12 ± 0.398 × 10⁶ conidia/ml) after 6 days of exposure. Crude extract from this strain was tested for contact toxicity and showed high activity in 3rd-instar nymphs and adults, with LC₅₀ values of 251.34 ± 49.54 and 315.46 ± 87.66 mg/l, respectively. In addition, crude extract at a concentration of 200 mg/l could significantly reduce fecundity in adults. These results revealed that the strain YZU 151121 may be useful in biopesticides for controlling pea aphid.     

Orientation and Shape Discrimination in Juveniles and Adults of the Mangrove Crab Aratus pisonii (H. Milne Edwards, 1837): Effect of Predator and Chemical Cues

Behavioral responses of juveniles and adults of the mangrove crab Aratus pisonii (H. Milne Edwards, 1837) to black geometric shapes of equal surface area was measured. Crabs were tested either in presence or absence of chemicals generated from two common predator species, the portunid crab Callinectes ornatus Ordway, and the soapfish Haemulon aurolineatum Cuvier, 1830. The present study tested the hypothesis that A. pisonii (1) has the capacity to orient to visual cues; (2) it discriminates between different visual objects based on a combination of chemical and visual information and (3) this behavior changes with age. When presented with single black targets in background water, juveniles oriented toward all shapes. This behavioral response was interpreted as visual orientation toward potential shelter. Among shapes, juveniles showed preference for the vertical rectangle, probably due to the recognition of natural visual elements like mangrove roots. In predator conditioned water, juveniles exhibited a stronger response than in background water. Thus, juveniles were able to detect by odor the potential presence of predators. Change in responsiveness between adults and juveniles was also demonstrated.     

Places and patterns — a study of context learning in honeybees

To investigate the priming of memories by contextual cues, bees were trained to negotiate two mazes in different places 25?m apart. In the first maze, bees flew leftwards when the inner wall of the maze was covered with 45° stripes or rightwards when the inner wall was coloured yellow. In the second maze, bees flew rightwards on viewing 135° diagonal stripes or leftwards on viewing blue. The trajectories evoked by 45° or 135° stripes were similar in both mazes. However, vertical stripes were treated like 45° stripes in maze 1 and like 135° stripes in maze 2. Contextual cues prime the response to stripes that are oriented in the training condition for that site so influencing responses to stripes in closely neighbouring orientations. What objects in a bee's surroundings determine its sense of place? Bees were trained to different visual patterns at two sites 40?m apart (A+ versus A– at site A, and E+ versus E– at site E). A+ was preferred over A– and E+ was preferred over E– at both training sites. A preference for A+ over E+ exhibited at site A dropped gradually with distance to suggest that spatial context includes both close and distant objects.     

Consequences of stress induced by heat on fitness of Delphacodes kuscheli and its yeast‐like endosymbionts

The planthopper Delphacodes kuscheli is the main vector of Mal de Río Cuarto virus in Argentina, disease that severely affects maize production. In this study, we investigated the effects of heat stress on fitness traits and on the number of its obligate yeast‐like symbionts (YLS). The exposition of newly‐hatched nymphs to 35°C for 3 days, a well‐known procedure used to reduce the number of YLS in planthoppers, was applied. To compare different fitness components between control and heat‐treated insects, we estimated nymphal instars development time, nymphal survival, adult body length, longevity, fecundity and fertility. Also, correlates of fitness, as proportion of sexes and wing forms of the emerging adults, were evaluated. In heat‐treated group, the nymphal developmental time increased due to an increase in the fifth instar duration, and the nymphal survival, body length of adults and fecundity were reduced when compared to control. There was a significant association between treatments (control and heat‐treated insects) and wing morphs. The heat treatment successfully reduced the number of YLS in third instar nymphs of D. kuscheli. Our results revealed the negative effect of heat stress on development, survival and reproduction of D. kuscheli and on the load of its YLS endosymbionts suggesting that YLS could play a crucial role in the development and reproduction of these planthoppers.     

Biotic Potential of a Short-Horned Grasshopper, <Emphasis Type="Italic">Oxya hyla hyla</Emphasis> Serville (Orthoptera: Acrididae) to Assess Its Biomass Producing Capacity

The growth of fishery and animal husbandry is being hindered by the scarcity of protein rich feed ingredients. Being rich in protein grasshoppers may be an alternative source of protein rich feed ingredients and hence rearing of these insects is essential for sustainable supply of insect biomass to the feed industry. The success of biomass production through insect rearing depends on the reproductive potentiality, rate of survival and growth of that particular insect. This study examines the biotic potential, fecundity, fertility, nymph mortality, life span and biomass production ability of a multivoltine grasshopper, Oxya hyla hyla (Serville, 1931) under semi-controlled condition. The grasshoppers are reared in 35 ± 2 °C temperature and 12L: 12D photoperiod and provided with food as fresh leaves of Cynodon dactylon (L.) Pers. to nymphs and Sorghum halepense (L.) Pers. to the adults. The result shows that a single pair of O. hyla hyla can lay on average 69.87 eggs in 4.96 ± 0.43 egg pods of which 7.37 ± 0.92 % eggs and 8.26 ± 0.99 % nymphs do not survive. The remaining survived nymphs metamorphose to 27.8 ± 3.35 male and 32.6 ± 3.21 female adults which produce a biomass of 18.48 ± 1.67 g wet weight. Thus a mass scale rearing of this insect may produce good amount of insect biomass which may be usable for fish and animal feed.     

Effects of Low Salinity on Adult Behavior and Larval Performance in the Intertidal Gastropod Crepipatella peruviana (Calyptraeidae)

Shallow-water coastal areas suffer frequent reductions in salinity due to heavy rains, potentially stressing the organisms found there, particularly the early stages of development (including pelagic larvae). Individual adults and newly hatched larvae of the gastropod Crepipatella peruviana were exposed to different levels of salinity stress (32(control), 25, 20 or 15), to quantify the immediate effects of exposure to low salinities on adult and larval behavior and on the physiological performance of the larvae. For adults we recorded the threshold salinity that initiates brood chamber isolation. For larvae, we measured the impact of reduced salinity on velar surface area, velum activity, swimming velocity, clearance rate (CR), oxygen consumption (OCR), and mortality (LC50); we also documented the impact of salinity discontinuities on the vertical distribution of veliger larvae in the water column. The results indicate that adults will completely isolate themselves from the external environment by clamping firmly against the substrate at salinities ≤24. Moreover, the newly hatched larvae showed increased mortality at lower salinities, while survivors showed decreased velum activity, decreased exposed velum surface area, and decreased mean swimming velocity. The clearance rates and oxygen consumption rates of stressed larvae were significantly lower than those of control individuals. Finally, salinity discontinuities affected the vertical distribution of larvae in the water column. Although adults can protect their embryos from low salinity stress until hatching, salinities <24 clearly affect survival, physiology and behavior in early larval life, which will substantially affect the fitness of the species under declining ambient salinities.     

The reproductive behaviour of Metopolophium festucae (Theobald) at different temperatures and on different host plants

Metopolophium festucae is a cold-hardy species: on young oat seedlings nymphs are produced from apterae at temperatures below 6 °C. Alatae are less well adapted to low temperatures: in a laboratory experiment the average daily production of nymphs from apterae was 0·96 at 10·2 °C and 2·71 at 22·8 °C; the corresponding figures for alatae were 0·42 and 1·81. Aphids on oats, wheat and Italian ryegrass have a slightly higher progeny production than on barley, timothy and cocksfoot: the adults produced on the cereals are heavier than those on the grasses. It is postulated that the aphids require a perennial crop on which to overwinter as nymphs or parthenogenetic adults; consequently successful colonization of cereal crops is rare.