4th Instar Nymphs Research Articles

Cold acclimation increases cold tolerance independently of diapause programing in the bean bug, Riptortus pedestris.

The bean bug (Riptortus pedestris) is a pest of soybeans and other legumes in Japan and other Asian countries. It enters a facultative adult diapause on exposure to short days. While photoperiodism and diapause are well understood in R. pedestris, knowledge of cold tolerance is very limited, as is information on the effect of diapause on cold tolerance. We examined the effect of photoperiod, cold acclimation, and feeding status on cold tolerance in R. pedestris. We found that cold acclimation significantly increased survival at -10°C in both long- and short-day adult R. pedestris. Since the difference in cold survival between long- and short-day cold-acclimated groups was only marginal, we conclude that entering diapause is not crucial for R. pedestris to successfully pass through cold acclimation and become cold tolerant. We observed similar effects in 5th instar nymphs, with both long- and short-day cold-acclimated groups surviving longer cold exposures compared with non-acclimated groups. Starvation, which was tested only in adult bugs, had only a negligible and negative impact on cold survival. Although cold tolerance significantly increased with cold acclimation in adult bugs, supercooling capacity unexpectedly decreased. Our results suggest that changes in supercooling capacity as well as in water content are unrelated to cold tolerance in R. pedestris. An analysis of metabolites revealed differences between the treatments, and while several metabolites markedly increased with cold acclimation, their concentrations were too low to have a significant effect on cold tolerance.

The isolation and identification of pathogenic fungi from Tessaratoma papillosa Drury (Hemiptera: Tessaratomidae).

BackgroundLitchi stink-bug, Tessaratoma papillosa Drury (Hemiptera: Tessaratomidae), is one of the most widespread and destructive pest species on Litchi chinensis Sonn and Dimocarpus longan Lour in Southern China. Inappropriate use of chemical pesticides has resulted in serious environmental problems and food pollution. Generating an improved Integrated Pest Management (IPM) strategy for litchi stink-bug in orchard farming requires development of an effective biological control agent. Entomopathogenic fungi are regarded as a vital ecological factor in the suppression of pest populations under field conditions. With few effective fungi and pathogenic strains available to control litchi stink-bug, exploration of natural resources for promising entomopathogenic fungi is warranted.Methods & ResultsIn this study, two pathogenic fungi were isolated from cadavers of adult T. papillosa. They were identified as Paecilomyces lilacinus and Beauveria bassiana by morphological identification and rDNA-ITS homogeneous analysis. Infection of T. papillosa with B. bassiana and P. lilacinus occurred initially from the antennae, metameres, and inter-segmental membranes. Biological tests showed that the two entomopathogenic fungi induced high mortality in 2nd and 5th instar nymphs of T. papillosa. B. bassiana was highly virulent on 2nd instar nymphs of T. papillosa, with values for cadaver rate, LC50 and LT50 of 88.89%, 1.92 × 107 conidia/mL and 4.34 days respectively.DiscussionThis study provides two valuable entomopathogenic fungi from T. papillosa. This finding suggests that the highly virulent P. lilacinus and B. bassiana play an important role in the biocontrol of T. papillosa in China. These pathogenic fungi had no pollution or residue risk, and could provide an alternative option for IPM of litchi stink-bug.

Predatory and control ability of Orius minutus to the diamondback moth (Lepidoptera: Plutellidae).

In order to make clear the suitability of eggs of Plutella xylostella as foodstuff of Orius minutus and the predatory and control ability of the bug to P. xylostella, the influence of praying on eggs of P. xylostella on development and reproduction of O. minutus was studied indoors with Myzus persicae as reference. The predation functional response was included to evaluate the control ability of O. minutus to P. xylostella. The results showed that O. minutus could finish its generation and reproduce offspring when fed on eggs of P. xylostella. The developmental durations of nymphal bugs (♀: 12.3 d, ♂: 12.2 d), the length of body of adult bugs [♀: (2.13±0.01) mm, ♂: (1.91±0.00) mm], the width of body of adult bugs [♀: (0.87±0.01) mm, ♂: (0.71±0.01) mm], the fecundity per female (12.7±1.1), the pre-oviposition period [(5.1±0.6) d] and the oviposition period [(3.7±0.4) d] all had no significant difference from those of treatment group of M. persicae; the longevity of adult bugs [♀: (10.7±1.4) d, ♂: (9.1±1.3) d] was longer than that of treatment group of M. persicae [♀: (8.5±0.5) d, ♂: (6.4±0.3) d]; the survival rate of nymphal bugs [(65.0±6.8)%] was lower than that of treatment group of M. persicae [(80.0±8.2)%], and the percentage of females was low. The predation functional responses of O. minutus to P. xylostella were all in accord with Holling2 equation. The largest amounts of caught per day (Nmax) of the 1st, 2nd, 3rd, 4th and 5th instar nymphal bugs to eggs of P. xylostella were 7.5, 16.3, 23.3, 29.1 and 38.7, respectively; the Nmax of the female and male adult to eggs of P. xylostella was 39.0 and 26.9, respectively; the Nmax of the 5th instar nymph to lower instar larva of P. xylostella was 41.3; and the Nmax of the female and male adult to lower instar larva of P. xylostella was 40.8 and 23.9, respectively. Single female and male pray eggs of P. xylostella up to (711.3±58.1) and (535.4±30.6), lower instar larvae of P. xylostella up to (371.9±52.0) and (253.9±32.3) during their whole lifetime, respectively. O. minutus could be reared with eggs of P. xylostella, and O. minutus has a good ability to control P. xylostella.

Effects of Induced Starvation onBagrada hilaris(Hemiptera: Pentatomidae) Survival

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a serious pest of cruciferous crops, including leafy crucifers grown in enclosed greenhouses in the Central Coast of California. These enclosed greenhouses face season-long risk of feeding injury to plantings of cruciferous crops. Understanding the survival ability of B. hilaris would help develop crop-free periods as a cultural tactic for B. hilaris control. A series of trials was conducted with 2nd–3rd and 4th–5th instar nymphs and male and female adults to determine how well they survive when they had full, partial, or no access to food and water sources. The treatments for the experiment were: (a) soil plus food (a piece of broccoli crown); (b) soil plus water; (c) soil-only; and (d) empty (no soil, water, and food). Bagrada hilaris were individually released into 20-ml ventilated scintillation vials that were deployed outside by burying them in the ground with only the ventilated top exposed for multiple days. Results show that B. hilaris survived between 3 and 6 d after deployment without access to food and water. In all experiments, survival of B. hilaris in the food or water treatments was significantly greater than in the soil-only and empty treatments on final day of the trial. Bagrada hilaris in the soil-only treatment had significantly lower number of live B. hilaris than in the empty treatment on the days before the final day of the experiment. The survival of B. hilaris that had access to food was not significantly different from those that had access to water.

The effect of gamma radiation on sterility and mating ability of brown planthopper, Nilaparvata lugens(Stål) in field cage

The brown planthopper, Nilaparvata lugens(Stål) is the major rice pest in Thailand. Adults and nymphs suck the sap from the rice plant causing it to wilt and transmitting the grassy stunt and the ragged stunt diseases. The population suppression by the sterile insect technique is overwhelmingly a function of mating between sterile males and wild females. The objectives of these experiments were to determine the suitable dose which induces partially sterile in N. lugens and their effect on wild population in the field cages. One-day-old 4th and 5th instar nymphs and adults were irradiated in a 60Co irradiator at the doses of 30, 60, 90 and 120 Gy. It was found that irradiation at the dose of 90 Gy induced complete sterility in female and 78.47 % sterility in males. The inherited sterility were transferred to their progenies and induced 51.46 and 77.00 % sterility in F-1 males and females. The irradiation as the mention dose did not affect mating ability. The competitiveness index was increased when the ratio of irradiated males per normal male was increased. The releasing irradiated males at 10 fold of normal males in field cages could suppress F-1 population 80.11 % and suppress F-2 population 80.32 % when compare with the control. This technique may be applied to delay and/or reduce seasonal increase of brown planthopper.

Phytophagy of the predator Podisus nigrispinus (Dallas, 1851) (Hemiptera: Pentatomidae) fed on prey and Brassicaceae.

The purpose of this study was to investigate the development and reproduction of the zoophytophagous predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed kale, broccoli and cabbage affects its. Nymphs and adults of this predator were fed on larvae of Plutella xylostella (L.) (Lepidoptera: Plutellidae) as prey with kale, cabbage, or broccoli. In the nymph period, the duration and prey consumption were similar with all the Brassicacea cultivar. However, nymph viability was higher for predators with broccoli leaves. The mean weight of 5th-instar nymphs, newly emerged females and the sex ratio were similar among the Brassicacea cultivars, while newly emerged males were heavier with kale and broccoli leaves. The supply of broccoli leaves resulted in greater oviposition, higher number of eggs per egg mass and longer longevity of P. nigrispinus males and females. Furthermore, the consumption of P. xylostella larvae by adult predators was higher with these cultivars. The net reproductive rate (R0) and mean generation time (T) were highest for predators with prey and broccoli leaves. The reproductive parameters of P. nigrispinus were enhanced when fed on P. xylostella larvae with and broccoli leaves, which can be an alternative diet in laboratory rearing of this predator.

Life stages of an aphid living under similar thermal conditions differ in thermal performance

Heat responses can vary ontogenetically in many insects with complex life cycles, reflecting differences in thermal environments they experience. Such variation has rarely been considered in insects that develop incrementally and experience common microclimates across stages. To test if there is a low level of ontogenetic variation for heat responses in one such species, the English grain aphid Sitobion avenae, basal tolerance [upper lethal temperature (ULT50) and maximum critical temperature (CTmax)], hardening capacity (CTmax) and hardening costs (adult longevity and fecundity) were measured across five stages (1st, 2nd, 3rd and 4th-instar nymphs and newly moulted adults). We found large tolerance differences among stages of this global pest species, and a tendency for the stage with lower heat tolerance to show a stronger hardening response. There were also substantial reproductive costs of hardening responses, with the level of stress experienced, and not the proximity of the exposed stage to the reproductive adult stage, influencing the magnitude of this cost. Hence hardening in this aphid may counter inherently low tolerance levels of some life stages but at a cost to adult longevity and fecundity. Our findings highlight the significance of ontogenetic variation in predicting responses of a species to climate change, even in species without a complex life cycle.

Regeneration of axotomized olfactory neurons in young and adult locusts quantified by fasciclin I immunofluorescence.

The olfactory pathway of the locust Locusta migratoria is characterized by a multiglomerular innervation of the antennal lobe (AL) by olfactory receptor neurons (ORNs). After crushing the antenna and thereby severing ORN axons, changes in the AL were monitored. First, volume changes were measured at different times post-crush with scanning laser optical tomography in 5th instar nymphs. AL volume decreased significantly to a minimum volume at 4days post-crush, followed by an increase. Second, anterograde labeling was used to visualize details in the AL and antennal nerve (AN) during de- and regeneration. Within 24h post-crush (hpc) the ORN fragments distal to the lesion degenerated. After 48 hpc, regenerating fibers grew through the crush site. In the AL, labeled ORN projections disappeared completely and reappeared after a few days. A weak topographic match between ORN origin on the antenna and the position of innervated glomeruli that was present in untreated controls did not reappear after regeneration. Third, the cell surface marker fasciclin I that is expressed in ORNs was used for quantifying purposes. Immunofluorescence was measured in the AL during de- and regeneration in adults and 5th instar nymphs: after a rapid but transient, decrease, it reappeared. Both processes happen faster in 5th instar nymphs than in adults.

Influence of the Desert Plant,Lotus corniculatuson the Protein Quantity and Glutathione-S-Transferase Activity ofSchistocerca gregaria

ABSTRACT: The desert plant, Lotus corniculatus (Fabaceae), inhabits the Saudi Arabian Sahara Desert. In these areas the desert locust, Schistocerca gregaria (Orthoptera, Acrididae), feeds on L. corniculatus containing the plant allelochemical linamarin; a cyanogenic glucoside that is usually toxic to polyphagous insects. Under laboratory conditions this plant was fed to S. gregaria. Haemolymph proteins and allelochemicals detoxification in S. gregaria, fed on L. corniculatus were assessed. Female 5th instar nymphs were reared on L. corniculatus or on wheat seedlings, Triticum aestivum, as control. In insects, glutathione-S-transferase is one of the most important detoxifying enzymes. The activity of glutathione-S-transferase (in units /gram) in the mid-gut tissues of 5th instar nymph females fed on L. corniculatus was significantly higher than in those fed on T. aestivum. The quantity of haemolymph proteins (in mg 100µl1) in adult locust females resulting from nymphs fed on L. corniculatus was significant...

Levels of Salivary Enzymes of Apolygus Lucorum (Hemiptera: Miridae), From 1st Instar Nymph to Adult, and Their Potential Relation to Bug Feeding.

In recent years, Apolygus lucorum has caused increasing damage to cotton and fruit trees in China. The salivary enzymes secreted by A. lucorum when sucking on host plants induce a series of biochemical reactions in plants, and the pre-oral digestion benefits the bug feeding. In this study, the food intake of A. lucorum from 1st instar nymphs to adults was measured, and the corresponding salivary activity of pectinase, amylase, cellulase, protease, polyphenol oxidase and peroxidase was determined. Daily food intake varied with developmental stage, peaking in 3rd and 4th instar nymphs. Pectinase, amylase, cellulase and protease were detected in both nymphal and adult saliva of A. lucorum, while neither polyphenol oxidase nor peroxidase was detected. Protease activity varied with food intake peaking at the 3rd-4th instar, and then slightly decreasing at the 5th instar. Levels of pectinase, amylase and cellulase increased significantly with the daily feeding level until the 3rd instar, corresponding with increasing damage to host plants. The activity of both cellulase and protease had a significant linear relationship with the average daily food intake. The increasing activity of enzymes in saliva explain stage-specific impacts of A. lucorum on the host plants, and suggest that optimal management of A. lucorum would be confined to its control threshold prior to the peak of daily feeding in the 3rd instar.

Gut symbiotic bacteria stimulate insect growth and egg production by modulating hexamerin and vitellogenin gene expression

Recent studies have suggested that gut symbionts modulate insect development and reproduction. However, the mechanisms by which gut symbionts modulate host physiologies and the molecules involved in these changes are unclear. To address these questions, we prepared three different groups of the insect Riptortus pedestris: Burkholderia gut symbiont-colonized (Sym) insects, Burkholderia-non-colonized (Apo) insects, and Burkholderia-depleted (SymBurk-) insects, which were fed tetracycline. When the hemolymph proteins of three insects were analyzed by SDS-PAGE, the hexamerin-α, hexamerin-β and vitellogenin-1 proteins of Sym-adults were highly expressed compared to those of Apo- and SymBurk--insects. To investigate the expression patterns of these three genes during insect development, we measured the transcriptional levels of these genes. The hexamerin-β gene was specifically expressed at all nymphal stages, and its expression was detected 4–5 days earlier in Sym-insect nymphs than that in Apo- and SymBurk--insects. However, the hexamerin-α and vitellogenin-1 genes were only expressed in adult females, and they were also detected 6–7 days earlier and were 2-fold higher in Sym-adult females than those in the other insects. Depletion of hexamerin-β by RNA interference in 2nd instar Sym-nymphs delayed adult emergence, whereas hexamerin-α and vitellogenin-1 RNA interference in 5th instar nymphs caused loss of color of the eggs of Sym-insects. These results demonstrate that the Burkholderia gut symbiont modulates host development and egg production by regulating production of these three hemolymph storage proteins.

Modeling population dynamics of yeast-like symbionts (Ascomycota: Pyrenomycetes: Clavicipitaceae) of the planthopper Delphacodes kuscheli (Hemiptera: Delphacidae)

Delphacodes kuscheli establish mutualistic relationship with yeast-like symbionts (YLS) that live in the fat body and are necessary for host survival and reproduction. We estimated for a host of age t, its body weight, W(t), and the number of YLS per host, YLS(t). The host body weight was calculated as: W(t) = Lm/[1+ e (d–kt)], (Lm = the maximum observed weight, and d and k are constants), and the fat body was considered a fixed proportion of W(t). We calculated the number of YLS per unit host body mass: α(t) = YLS(t)/W(t). We also calculated the number of YLS per host, cYLS(t), and analyzed the pattern of variation in both sexes adapting the expression of the logistic model: cYLS(t) = KNoert/K+(ert -1)No, (No = initial number of YLS, r = intrinsic per capita rate of natural increase, and K = variable carrying capacity). In females the carrying capacity varied according to a constant proportion of the host’s weight: K(t) = αW(t). In males α(t) was considered a decreasing function of the host age: K(t) = α(t)W(t). The coefficients No, α, and r were subjected to parameterization. We found that the patterns of W(t) and YLS(t) of D. kuscheli were similar to other planthoppers. In females YLS increased up to the adult stage and then remained almost constant, varying similarly to individual weight. In males YLS increased up to the 5th instar nymph as the individual weight did, but the number of YLS decreased in the adult stage and the correlation was not so good. The calculated number of YLS per host matches reasonably well with the number estimated experimentally both in females and males. This is the first study that quantified and modeled the dynamics of YLS endosymbionts in a Neotropical planthopper pest. The models will be used in future studies for better understand the experimental reduction of YLS in young nymphal stages.

New insights into the infection of the American cockroach Periplaneta americana nymphs with Metarhizium anisopliae s.l. (Ascomycota: Hypocreales).

To study the marked resistance of Periplaneta americana to entomopathogenic Metarhizium anisopliae. The low susceptibility of 4th instar nymphs applied topically with conidia seemed to be related to an active removal of conidia by the cockroach and to a disabled or retarded germination and subsequent development of conidia on the cuticle (up to 80% germination in the next 7days after application). Inhibitions or delays of germination were related to the composition of the epicuticular fatty acids (30·1% w/w oleic, 28·3% w/w linoleic, 24·5% w/w palmitic and 11·7% w/w stearic acid) reported here. Propagules invading the nymphs through the cuticle took at least 3days to reach the haemocoel, and no propagules were found after day 8 post-treatment. Strain IP 46 infected >50% of nymphs treated with doses ≥2×104 hyphal bodies (HB)nymph-1 and reduced the survival of nymphs ≤50%. Most nymphs (>70%) survived after injection of 6×103 and 2×103 HBnymph-1 . Findings emphasize a distinct resistance of nymphs of the American cockroach to infections by M.anisopliae. Our findings provide support for the development of biological control of this synanthropic cockroach pest.

Insecticidal activity of neem oil against Gyropsylla spegazziniana (Hemiptera: Psyllidae) nymphs on Paraguay tea seedlings

Gyropsylla spegazziniana (Paraguay tea ampul) is one of the most important pests of Paraguay tea plants, and prohibition of synthetic insecticide use for control of this pest has led to the search for alternative methods. This laboratory study aimed to compare different control strategies for G. spegazziniana, utilizing a commercial neem seed oil product. Paraguay tea seedlings were treated with neem oil solution both pre- and post-infestation with 5th instar nymphs. The systemic action of neem oil was also evaluated by treating plant soil with the neem oil solution, followed by transfer of the insects to plants 24 h post-treatment. Spray treatments were effective against the pest, especially post-infestation (80% mortality), demonstrating the potential of neem oil for control of the Paraguay tea ampul. No significant effects were observed with respect to systemic activity.

Partial consumption of different species of aphid prey by the predator Macrolophus pygmaeus (Hemiptera: Miridae)

The partial consumption of prey refers to when a predator does not consume all the digestible biomass of an animal it has killed. The frequency of partial consumption of prey by the polyphagous predator Macrolophus pygmaeus (Hemiptera: Miridae) was recorded for different species of prey and prey population structures, in single and mixed prey species patches. All the instars of the aphid, Aphis gossypii, were provided as prey alone or together with Myzus persicae or Macrosiphum euphorbiae. Numbers killed were determined when equal (10 nymphs of each instar, 40 in total) or unequal numbers (higher numbers of young nymphs but again 40 in total) of nymphs were placed on an eggplant leaf in a plastic Petri dish. In each dish a single 5th instar nymph of the predator was introduced and the numbers killed and numbers of partially consumed aphids were recorded after 24h, at 25 ± 1°C. The numbers of A. gossypii killed were higher than those of the other species of prey used. The frequency of partially consumed prey was highest when A. gossypii was offered alone in equal numbers of each instar, followed by when A. gossypii was provided together with M. persicae in unequal numbers of instars (23.6% and 11.2%, of the total mortality, respectively). Killed but not consumed prey was also recorded, at frequencies that reached 10.7% of the total mortality when A. gossypii was provided alone in equal numbers of each instar. For M. persicae and M. euphorbiae, these percentages were significantly lower. The higher frequency of this behaviour when A. gossypii was the prey may be related to its lower nutritional quality for the predator. The effect of prey instar was not significant. These results indicate that in determining the numbers killed by a predator, partially consumed prey may make up a significant part of the total kill and thus should be taken into consideration.

Movement Behavior and Host Location Ability of Corythucha ciliata.

Insect movement behavior is highly important in entomological population ecology, behavioral ecology and conservation, and in invasion ecology. In this study, we used an exotic lace bug (Corythucha ciliata) as a model organism to address the hypothesis that an insect species invading a new area has a high host location ability and rapid mobility by which it can be successfully carried to a new habitat. To test this hypothesis, three movement parameters (speed, duration and distance) of C. ciliata were assessed using laboratory and field observations. We found that 5th-instar nymphs of C. ciliata could move as far as 750 cm throughout their lifespan and that they moved an average of 0.038 m/min during the first 15 minutes after release, which was significantly farther than that of other instars. Of the tested nymphs, 21.85% could locate their host trees; of adults released 20 m from hosts, 11% reached the host trees on the first day, with an average flight distance of 22.14 m and a maximum flight distance of 27 m. The results of this study partly explain the mechanism of rapid diffusion. These results are also important for predicting population spread, improving eradication surveys, and managing future introductions of C. ciliata.

Effect of Harmonic Radar Tagging onLycorma delicatula(Hemiptera: Fulgoridae) Nymphal Mobility and Survivorship

The spotted lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoridae), has recently emerged as an invasive pest in the United States, threatening the grape and tree fruit industries. The biology of L. delicatula is poorly known. This invasive pest has rapidly spread and established itself in new regions (e.g., South Korea), taking advantage of a wide range of host plants, but virtually no studies of the dispersal capacity and patterns of the species have been published. Harmonic radar tracking provides a new tool to study the dispersal of small animals such as insects in natural field settings. In this study, we discuss procedures that allow secure attachment of harmonic radar tags on the 4th instar nymphs of L. delicatula. The adhesive bond strength between the radar tag and the nymph was sufficiently great for operational use, yielding 431.10 ± 43.37 g forces (mean ± SE). Variations in L. delicatula body size of did not affect the adhesive bond strength. Neither horizontal mobility nor vertical climbing ability of L. delicatula was affected by radar tagging when compared with untagged controls. Also, there was no significant difference in the jumping ability of radar-tagged and untagged insects. Finally, radar tagging did not affect the survivorship of L. delicatula over a 3 d test period. The results of this study indicate that the harmonic radar system can be applied successfully to 4th instars of L. delicatula without changing their mobility and survivorship. This technology facilitates study of the dispersal capacity and behavior of this invasive species under natural field conditions, and this information can serve as a basis for the development of effective monitoring and management strategies.

Description of the 5th instar nymph of Oenopiella punctaria (Stål, 1859) Hemiptera: Heteroptera: Pentatomidae), with new distributional records from Southern Patagonia.

The 5^th instar nymph of Oenopiella punctaria (Stål, 1859) is described and illustrated for the first time, together with new distributional records from Patagonia. The new records are from Santa Cruz Province (Argentina), and the Magallanes Region (Chile). The latter is the southernmost record for this species and also for the Carpocorini in South America. In light of the new data, the biogeography of Oenopiella is discussed, and it is concluded that an Andean origin may be possible.

Rearing Orius strigicollis (Hemiptera: Anthocoridae) on an alternative diet of brine shrimp, Artemia salina (Anostraca: Artemiidae)

We investigated the use of cysts of the brine shrimp Artemia salina Linnaeus as an alternative diet to eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller, in rearing the biological control agent Orius strigicollis (Poppius). Although 3rd- and 4th-instar nymphs and 1st to 5th-instar nymphs took longer to develop when fed on brine shrimp cysts with shells than on E. kuehniella eggs, the difference was within or approximately 1 day. The nymphal survival and development were considered to be similar in O. strigicollis fed the two diets. In reproductive characteristics, adult female bugs fed eggs of E. kuehniella or brine shrimp cysts with shells performed better than those fed brine shrimp cysts without shells. Brine shrimp cysts with shells would, thus, be useful for reliably and economically rearing O. strigicollis. This rearing method may also prove useful as part of the quality assurance for commercially produced O. strigicollis.

Evidence for the presence of biogenic magnetic particles in the nocturnal migratory brown planthopper, Nilaparvata lugens.

Biogenic magnetic particles have been detected in some migratory insects, which implies the basis of magnetoreception mechanism for orientation and navigation. Here, the biogenic magnetic particles in the migratory brown planthopper (BPH), Nilaparvata lugens were qualitatively measured by SQUID magnetometry, and their characteristics were further determined by Prussian Blue staining, electron microscopy and energy dispersive x-ray spectroscopy. The results indicate that there were remarkable magnetic materials in the abdomens and not in the head or thorax of the 3rd–5th instar nymphs, and in macropterous and brachypterous female and male adults of BPH. The size of magnetic particles was shown to be between 50–450 nm with a shape factor estimate of between 0.8–1.0 for all the tested BPHs. Moreover, the amount of magnetic particles was associated with the developmental stage (the 3rd–5th instar), wing form (macropterous vs. brachypterous) and sex. The macropterous female adults had the largest amount of magnetic particles. Although the existence of magnetic particles in the abdomens of BPH provides sound basis for the assumption of magnetic orientation, further behavioral studies and complementary physical characterization experiments should be conducted to determine whether the orientation behavior of BPH is associated with the magnetic particles detected in this study.