Small Larvae Research Articles

Effect of Seawater Acidity on the Initial Development of Kumamoto Oyster Larvae Crassostrea sikamea (Amemiya, 1928)

The oceans have absorbed more than 40% of the carbon dioxide (CO2) generated by anthropogenic activities, causing a decrease in the average pH of 0.1 units in seawater since preindustrial times. This phenomenon has been called “ocean acidification.” This change poses serious threats to the cultivation of oysters and especially to larval and spat production, activities carried out in coastal and estuarine areas, where pH levels are currently below the IPCC scenario for the year 2100 of pH = 7.8. The goal of the present work was to experimentally evaluate the effect of simulated acidification (pH 7.39 ± 0.04) on the culture in a short-term trial of Kumamoto oyster larvae Crassostrea sikamea taking the current ocean pH conditions (pH 8.116 ± 0.023) as a reference. The evaluation was carried out in an experimental system with continuous water flow and pH manipulation by CO2 bubbling. Veliger larvae (6-day-old postspawn) were cultured at a density of six larvae mL–1 and fed with a monoalgal diet based on Isochrysis galbana at 30,000 cells mL–1. Mortality (%) and growth (shell length in µm) were evaluated, and damage to larval morphology (determined using scanning electron microscopy) and Ca2+ contents in the shells (%) were quantified by X-ray fluorescence. The results show a high sensitivity of C. sikamea veliger larvae to low pH levels with negative impacts on growth and survival, decreases in the Ca2+ concentrations of the shells, and the presence of morphological anomalies during the prodissoconch I stage, which were observed after the first 24 h of cultivation in experimental conditions and became progressively more evident, especially by the sixth day of culture. Acute exposure to a low pH and a saturation of aragonite (Ωar) <1 caused poor calcification in C. sikamea larvae, causing negative effects on larvae, such as shell lesions during development, smaller larvae, and higher mortality and relation to a control pH.

Spatial and Temporal Distribution of the Early Life History Stages of the Native Olympia Oyster Ostrea lurida (Carpenter, 1864) in a Restoration Site in Northern Puget Sound, Wa

For effective long-term restoration of depleted marine species, it is critical that populations are able to replenish themselves through reproduction. The Olympia oyster Ostrea lurida (Carpenter, 1864), the only native oyster species on the West Coast of North America, is the subject of a number of restoration efforts across its range. Information about the distribution of its early life history stages is critical for the design of effective and connected restoration networks. In this study, spawning adults (brooders), planktonic larvae, and settlers were mapped in Fidalgo Bay, Anacortes, WA, an active restoration site in the Salish Sea. Sampling was conducted weekly from May through August 2013 at five intertidal and three subtidal stations. Brooding adults, planktonic larvae, and settlers were sampled. Environmental variables measured were temperature, relative water flux (a proxy for flow), tidal height, and submersion time of traps and shell strings. A low percentage of individuals sampled were brooding (maximum 13%) throughout the sampling period, but abundance peaked in early July. Small planktonic larvae (153–243 µm) were present throughout the sampling period, but peaked in mid-July, whereas large larvae (243–333 µm) were mostly only found in mid-July. Overall, there was high variability in the distribution of larvae and settlement among various locations or depths throughout Fidalgo Bay. Planktonic larvae and settlers were much more abundant near conspecifics and at a trestle bridge that could have affected hydrodynamics and, therefore, settlement. In addition, settlement increased with increasing water flow in the intertidal, but not in the subtidal, zone. More settlement occurred at –0.3 m below mean lower low water (MLLW) than at stations above or below this elevation, indicating that postlarvae prefer to settle at an intermediate elevation band in the intertidal zone. Temperature was the most important variable measured, with an association between the increasing presence of planktonic larvae and settlement with increasing temperature. In sum, prerecruitment processes appear to be very important in determining the spatial distribution of Olympia oysters in Fidalgo Bay. These results suggest that restoration of Olympia oysters is improved by the addition of appropriate substrates in sites that contain conspecifics and are just below MLLW.

Larval interactions between two aphidophagous coccinellids in sweet pepper.

Antagonistic interactions among predators have the potential to dampen top-down impacts on a shared pest. Strong cannibalism by adults and larvae on eggs along with a stronger intraguild predation by Eriopis connexa on Cycloneda sanguinea (Coccinellidae) than vice versa had been documented. The intensity and direction of these interactions could vary with the larval instar. We calculated aggressiveness, attack, and predation rates between larvae in the laboratory and studied both larval mortality and within-plant distribution in plants. Despite high attack rates, larvae of both species usually escaped from predation, except for the fourth vs. second-instar combinations, where the smaller larvae were more vulnerable to predation than the larger. Successful predation by E. connexa fourth-instars on C. sanguinea second-instars frequently occurred. All interactions between larvae became relaxed when extraguild prey were present. The larval mortality within the plants was influenced by the availability of extraguild prey only. Larvae of both species promptly dispersed outside the plant when prey became unavailable. With the extraguild prey present, the larvae of both species initially preferred the plant upper stratum in both combinations, but then dispersed. This study suggests that the defensive capability and larval dispersal could prevent cannibalism and intraguild-predation interactions.

Solitary Intramuscular Cysticercosis, a Case Report from 47-year-old Man

Cysticercosis is a common parasitic infection in developing countries involving the central nervous system (CNS), adnexal structures of the eye, skeletal muscle, and subcutaneous tissue. The principal mechanism of transmission is through ingestion of <i>Taenia Solium</i> eggs or contamination of fruits and vegetables fertilized with contaminated faecal materials. The eggs hatch within the small intestine and larvae travel to through blood vessels to the subcutaneous tissue, muscle, CNS, eye and other tissues where they eventually form cyst with host inflammatory response. The clinical features are variable from painful or painless swelling in the subcutaneous tissue to neurocysticercosis comprising of symptomatic headache, seizures and focal neurologic deficit. Solitary intramuscular cysticercosis without CNS involvement have also been reported, although it is rare. Thus, we present a case of solitary intramuscular cysticercosis involving bicep muscle in a 47-year-old engineer, a rare site without any neurologic or systemic manifestation.

Diet and food partitioning between juvenile of Epinephelus coioides (Perciformes: Epinephelidae) and other co-existing juvenile fishes in shallow waters of Thailand and Malaysia

This work examined diet composition of the juvenile orange-spotted grouper, Epinephelus coioides, and its trophic association with other juvenile fish species in tropical estuarine habitats during recruitment. From December 2015 to March 2016, juveniles were collected, their stomachs excised, preserved and analyzed. Small shrimps and amphipods, especially Grandidierella sp. and Elasmopus sp., were the most common food resources sharing among the most species. Epinephelus coioides predominantly ingested small shrimp, Grandidierella sp., Elasmopus sp. and fish larvae and had the greatest trophic overlap with Palatrus scapulopunctatus. Fish size, location and month significantly affected fullness indices and food items diversity in E. coioides. It is clear that the larger the size of E. coioides and its mouth opening, the larger the size of items ingested. This study confirms the ontogenetic dietary shift of juvenile E. coioides during recruitment season by starting as amphipod and small shrimp feeder and shifting to shrimp and fish larvae predator as they grow. This finding is fundamental to understanding how juvenile E. coioides cope with different conditions and its association with other co-existing species during the recruitment period.

Impact of Various Bt Cotton Traits and the Application of an Insecticide on the Within Plant Distribution of Helicoverpa zea (Lepidoptera: Noctuidae) Larvae and Injured Floral Structures

Previous studies have indicated that the expression of insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) in cotton can have a significant influence on the behavior of bollworm larvae (Helicoverpa zea, Lepidoptera:Noctuidae). This suggests that the particular Bt protein produced by a cotton variety may need to be considered when determining the most ideal scouting methods to utilize for bollworm. NonBt, WideStrike (producing Cry1Ac + Cry1F Bt insecticidal proteins), and Bollgard II (Cry1Ac + Cry2Ab) cotton varieties were planted and either treated with an insecticide or left untreated. The presence of H. zea larvae and their feeding injury were recorded according to their location in the canopy and type of floral structure where they were found. Results from comparison of larval and injury distributions indicated no significant differences between the different cotton varieties tested, and that insecticide treatment had minimal impact on this distribution. Larval size was generally associated with location in the canopy, suggesting that larvae tend to move towards the middle of the canopy as they age. The effect of different Bt cotton technologies appears to associate with how quickly larvae move to preferred feeding sites rather than their preference for particular feeding sites. These results suggest that scouting methods could be standardized independently of the presence of a Bt cotton trait or previous insecticide application. Focusing scouting efforts on the middle portion of the canopy (i.e., nodes 6-9) should increase the detection of small larvae and ‘fresh’ injury and be less influenced by previous insecticide applications.

The hydrodynamic regime drives flow reversals in suction-feeding larval fishes during early ontogeny.

ABSTRACTFish larvae are the smallest self-sustaining vertebrates. As such, they face multiple challenges that stem from their minute size, and from the hydrodynamic regime in which they dwell. This regime, of intermediate Reynolds numbers, was shown to affect the swimming of larval fish and impede their ability to capture prey. Prey capture is impeded because smaller larvae produce weaker suction flows, exerting weaker forces on the prey. Previous observations on feeding larvae also showed prey exiting the mouth after initially entering it (hereafter ‘in-and-out’), although the mechanism causing such failures had been unclear. In this study, we used numerical simulations to investigate the hydrodynamic mechanisms responsible for the failure to feed caused by this in-and-out prey movement. Detailed kinematics of the expanding mouth during prey capture by larval Sparus aurata were used to parameterize age-specific numerical models of the flows inside the mouth. These models revealed that for small larvae which expand their mouth slowly, fluid entering the mouth cavity is expelled through the mouth before it is closed, resulting in flow reversal at the orifice. This relative efflux of water through the mouth was >8% of the influx through the mouth for younger ages. However, similar effluxes were found when we simulated slow strikes by larger fish. The simulations can explain the observations of larval fish failing to feed because of the in-and-out movement of the prey. These results further highlight the importance of transporting the prey from the gape deeper into the mouth cavity in determining suction-feeding success.

Palatability and Defense of Eastern Newt (Notophthalmus viridescens) Larvae and Metamorphic Juveniles against Predatory Dragonfly Nymphs

We examined the predator–prey relationship between nymphs of the predatory dragonfly Anax junius (Common Green Darner) and larval and metamorphic Notophthalmus viridescens (Eastern Newt), some of which may contain the potent neurotoxin, tetrodotoxin. First, we conducted a palatability study to determine which life-history stages were palatable to dragonflies. We also tested the metamorphosis and survival rates of larval newts when exposed to predatory dragonflies in small microcosms. Finally, we tested the predator avoidance behavior of larval newts in response to chemical cues from a control, food stimulus, and predatory dragonflies. All life-history stages (small and large larvae, and recent metamorphs) were palatable to dragonflies. In microcosm trials, we found that newt larvae had a lower chance of surviving and transforming when dragonflies were present compared to a control. Finally, newt larvae decreased movement significantly when exposed to predatory dragonfly stimulus compared to either a control or food stimulus. These results suggest dragonflies are effective predators of newts from hatching through metamorphosis. However, the larvae do possess behavioral avoidance mechanisms that likely reduce the risk of predation by dragonflies.

Gut microbiota metabolic potential correlates with body size between mulberry-feeding lepidopteran pest species.

Many insect pests rely on microbial symbionts to obtain nutrients or for defence, thereby allowing them to exploit novel food sources and degrade environmental xenobiotics, including pesticides. Although Lepidoptera is one of the most diverse insect taxa and includes important agricultural pests, lepidopteran microbiotas, particularly functional traits, have not been studied widely. Here, we provide a comprehensive characterization of the gut microbiota across multiple mulberry-feeding lepidopteran species, resolving both community structure and metabolic potential. Our results indicate abundant bacteria inside the gut of larval Lepidoptera. However, even though they were fed the same diet, the structures of the bacterial communities differed in four major mulberry pest species, suggesting host-specific effects on microbial associations. Community-level metabolic reconstructions further showed that although taxonomic composition varied greatly, carbohydrate and amino acid metabolism and membrane transporter were key functional capabilities of the gut bacteria in all samples, which may play basic roles in the larval gut. In addition, principal coordinate analysis (PCoA) of gut bacterial-predicted gene ontologies revealed specialized features of the microbiota associated with these mulberry pests, which were divided into two distinct clusters (macrolepidopterans and microlepidopterans). This pattern became even more prominent when further Lepidoptera species were involved. A suite of gut microbiota metabolic functions significantly correlated with larval size; the metabolism of terpenoids and polyketides, xenobiotics biodegradation and metabolism were specifically enriched in large species, while small larvae had enhanced nucleotide metabolism. Our report paves the way for uncovering the correlation between host phenotype and microbial symbiosis in this notorious insect pest group. © 2019 Society of Chemical Industry.

Characterization of Nanostructured Silica as Carrier for Insecticides Deltamethrin, Pyriproxyfen, and Chlorpyrifos and Testing the Insecticidal Efficacy Against Trogoderma granarium (Coleoptera: Dermestidae) Larvae.

Abstract Nanostructured silica can be used as a carrier of pesticides to enhance stability and controlled release of agrochemicals with an effective concentration on target pests. Silica nanoparticles (SNPs) were synthesized by sol–gel process and employed as a carrier of three different insecticides including deltamethrin, pyriproxyfen, and chlorpyrifos. The SNPs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis and the insecticides-loaded in SNPs were characterized by transmission electron microscopy (TEM). The toxicity of insecticides alone and loaded in SNPs was evaluated against small and large larvae of Trogoderma granarium Everts on concrete surfaces. The immediate mortality was counted after 1, 3, and 7 d of exposure, and then surviving individuals were transferred to untreated surfaces for seven more days, with delayed mortality was recorded. Small larvae were more susceptible than large ones on all insecticide treatments. In addition, insecticides loaded in silica nanoparticles were more effective when compared with application of the insecticides alone. For immediate mortality, deltamethrin loaded in SNPs was the most efficient treatment causing 70.5% mortality on small and 55.5% mortality on large larvae after 7 d of exposure to the highest concentration. Pyriproxyfen loaded in SNPs caused low immediate mortality, but the mortality increased in delayed count indicated that the insecticide could control the larvae even after they have been removed from treated surfaces. It can be concluded that loading insecticides in SNPs could significantly increase their insecticidal efficiency, but this increase was compound-dependent.

Challenges in chemical management of soybean looper (Chrysodeixis includes) using several insecticides

Soybean looper, Chrysodeixis includens (Walker, [1858]) (Lepidoptera: Noctuidae), is the most important caterpillar pest in Brazil due to its high tolerance to insecticides and control failures that have been reported in fields. Based on this, we assessed the performance of several insecticides against C. includens on soybean over three seasons (2014, 2015, and 2016), performing four experiments in southern Brazil. Experiments I / 2014, II / 2015, III / 2016 were carried in completely randomized block designs with eight insecticides. Experiment IV / 2016 was arranged in completely randomized block design in an 8 x 2 factorial arrangement, eight insecticides x two spraying time. Mortality of small (&lt; 1.5 cm) and large (&gt; 1.5 cm) soybean looper larvae was assessed with a vertical beat cloth, sampling in each plot 1.0 m2 at 3, 7 and 10 days after spray. Percentage of defoliation injury was assessed visually comparing to a scale of soybean leaf injury in experiment IV / 2016. Data were subjected to one-way (type I SS) analysis of variance (ANOVA) using the general linear models. The insecticides indoxacarb and chlorfenapyr had consistently high mortality upon small and large larvae of C. includens. Spinosyn, spinosad and spinetoram insecticides showed higher effect over small larvae (&lt; 1.5 cm) than large (&gt; 1.5 cm). Number of spraying was significant for spinetoram and indoxacarb that increased mortality of large larvae (from 4.50 to 2.75 and from 3.75 to 0.87 larvae m-2, respectively) and reduced defoliation injury significantly (from 22.5% to 9.3% and from 14.5% to 3.3%, respectively) with two applications. The treatment chlorfluazuron+acephate showed low defoliation injury in 2016 but did not affect larval density. Chlorfenapyr showed reduced defoliation (3.0%) and low larvae density (1.37 larvae m-2) with only one application. Spinosyns have satisfactory control of small larvae and indoxacarb and chlorfenapyr show high mortality of both sizes, small and large larvae. Therefore, we recommend that 7 days from the first one, a second application should be considered for indoxacarb, and spinetoram to achieve higher mortality. Considering our results, we demonstrate that the satisfactory control of soybean looper larvae is difficult to achieve with most chemical insecticides. It needs a more accurate management strategy of C. includens in soybeans.

The food composition of Halmahera walking shark (Hemiscyllium halmahera)

Halmahera walking shark or Halmahera epaulette shark (Hemiscyllium halmahera) is known as a shallow endemic shark species of the Halmahera island of Indonesia. This research was conducted with the aim to know the composition of H. halmahera food, as part of the parental domestication effort for cultivation and conservation of endemic species. Six individual of H. halmahera were obtained by simple random sampling in waters of Kao Bay threshold, North Maluku in October 2017. The result of gastric contents analysis using frequency occurrence method showed that H. halmahera is classified as benthic coral reef population with varied food composition consisted of small fish scales (96.6%), Annelida (2.1%), fish larvae (0.3%), Mysis (0.2%), Eucalanus sp (0.2%), Pseudeuphausia (0.2%), Hyperia sp, Acrocalanus sp, Copilia sp, and fish bone respectively (0.1%). Type of food that is always present in all stomach samples, namely the Annelida which contains a lot of proteins, vitamins and minerals even iodium that are useful for growth and the immune system.

Evaluation of manipulative effects by an ichneumonid spider-ectoparasitoid larva upon an orb-weaving spider host (Araneidae: Cyclosa argenteoalba) by means of surgical removal and transplantation

Surgical removal and larval transplantation experiments were carried out to evaluate behavioral manipulative effects caused by larvae of the polysphinctine ichneumonid, Reclinervellus nielseni (Roman, 1923), on its orb-weaving spider host, Cyclosa argenteoalba Bösenberg & Strand, 1906 (Araneidae). Residual behavioral effects on spiders from which parasitoid larvae had been removed were recognized and are described. Some transplanted parasitoid larvae also successfully consumed alternative spider hosts provided to them, and completed metamorphosis. The removal experiment supports previous hypotheses proposed by Eberhard, that larval effects involve chemicals, which are still unidentified and are dosage-dependent, because (1) spiders with parasitoid larvae removed continued to show manipulated behavior, and (2) the later in their development that the parasitoid larvae were removed, the more acute remaining effects were (e.g., production of V radii, new hub loops and silk decorations on webs). Further, the results support the idea that the spider's web-building behavior is composed of independent units (modules), because whether or not specific web features were produced depended on when the larva was removed. Transplantation experiments provide a new technique for rearing parasitoid larvae whose host spider dies: penultimate instar parasitoid larvae were successfully reared following their removal from their original host by providing them with another host spider held by a mesh. Transplantation of a small young larva by gluing it onto another host that was released after successful transplantation, caused the new host to produce a modified web identical to the “cocoon” webs typically produced by parasitized spiders. This shows that venom injected by the adult parasitoid prior to oviposition is not necessary to induce behavioral changes in the host, which can be caused entirely by wasp larval secretions.

Shrinking Body Size and Physiology Contribute to Geographic Variation and the Higher Toxicity of Pesticides in a Warming World.

To improve current and future risk assessment of pesticides under global warming, mechanistic insights and consideration of daily temperature fluctuations (DTFs) are needed. One overlooked mechanism how both higher mean temperatures and DTFs may increase toxicity is by reducing body size (temperature-size-rule). We studied whether a higher mean temperature and DTF magnified chlorpyrifos toxicity in Ischnura elegans damselfly larvae, and whether this was mediated by temperature-induced reductions in body size and/or physiological changes. The lethal effects of chlorpyrifos were magnified at the high mean temperature (up to ∼15%) and under DTF (up to ∼33%), and especially at their combination (up to ∼46%) indicating synergisms. This highlights that not only considering DTFs, but also their interaction with higher mean temperatures is pivotal for realistic predictions of pesticide toxicity. Both higher temperatures and DTFs resulted in smaller larvae, which were more sensitive to chlorpyrifos. Notably, the DTF-induced smaller body sizes, as well as the higher oxidative damage to lipids, contributed to the higher chlorpyrifos toxicity under DTF. By integrating the temperature-size rule and size-pesticide sensitivity pattern we provide proof-of-principle for a novel, likely general mechanism contributing to geographic variation and the higher toxicity of pesticides in a warming world.

Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) Affects on Immature Stages of Chrysodeixis includens (Lepidoptera: Noctuidae)

Soybean looper (Chrysodeixis includens) is an important defoliating pest, which has caused significant losses in Brazilian soybean crops. The present study evaluated the foliar consumption, feeding period and mortality of small (&amp;lt; 1.0 cm), medium (1.0 to 2.0 cm) and large (&amp;gt; 2.0 cm) C. includens larvae after infection by the virus Chrysodeixis includens nucleopolyhedrovirus (ChinNPV), isolate Chin-IA (I-A). The bioassay was performed in a completely randomized design organized in a 3 &amp;times; 2 factorial combination (three size of larvae fed on soybean leaf discs, either treated or not with 4.0 &amp;times; 1011 PIB ha-1 suspension of virus) with ten replicates per treatment. The average consumption of all three sizes C. includens larvae were significantly reduced after ingestion of soybean discs treated with virus, compared to the larvae from control treatment. The total consumption reduction was 95.6%, 69.4% and 45.9% for the small, medium and large larvae, respectively. Feeding period was significatively reduced for small and medium larvae infected by the virus, but not for large larvae. The corrected mortality level of soybean loopers ranged from 70 to 90% and was not significant different between the three larval sizes. The behavior and physiological alterations of larvae started on the third day, and the mortality occurred between fifth and sixth day after ingestion of infective particles of virus, therefore reducing their damage abilities. Based on the results obtained, ChinNPV can be considered as an important tool within integrate management to control C. includens, mainly when small larvae were predominant in soybean crops.

Trophic behaviour of the dragonfly &lt;i&gt;Cordulegaster boltoni&lt;/i&gt; (Insecta: Odonata) in small creeks in NW Italy

The order Odonata comprises many predaceous species that inhabit aquatic systems, and a few that are restricted to flowing waters. Cordulegaster boltoni is a widespread Odonata in Europe, which usually inhabits small lotic systems. In this study we analysed the gut contents of C. boltoni immature stages, collected in the Rocchetta Tanaro Natural Park (Italy, Piemonte). Two hundred and eleven individuals were collected, and their diet analyzed by dissection or clearing. Larvae appeared to be opportunistic predators, feeding on a variety of prey. Aquatic insects dominated their diet, while crustaceans, annelids, molluscs and terrestrial invertebrates were sporadically observed in the gut contents. An ontogenetic shift in the diet was detected, as small larvae consumed different prey than large ones. Our study suggests that C. boltoni is one of the dominant predators in the benthic communities of lowland small order streams of Piemonte, which, because of their environmental characteristics, are devoid of fish and stoneflies.

The effect of nutritional condition by two nucleic acid derived indices on the growth to post-flexion of Atlantic bluefin tuna and Atlantic bonito larvae

Notochord flexion increases the swimming capacity of fish larvae, aids in the capture of mobile prey, and coincides with the timing of when the physiological capacities of larvae begin to develop significantly, allowing an early shift to piscivory. Therefore, reaching the flexion stage as soon as possible can be considered beneficial for the growth and survival of the larvae. Individual growth differences of larvae from the same cohort are very common before reaching flexion and the potential explanation is still unknown. In this study, we examined if the nutritional status of the larvae, measured by the RNA:DNA and DNA:DW ratios, explains the differences in the development of notochord flexion in laboratory-reared Atlantic bluefin tuna (ABFT; Thunnus thynnus) and Atlantic bonito (AB; Sarda sarda) larvae. Moreover, we described the ontogeny of the different stages and condition indices. The daily average condition of ABFT estimated by the RNA:DNA and DNA:DW ratios increased with larval age and developmental stage, whereas in AB it was not. In both species, bigger larvae at a specific age had higher nutritional condition than smaller larvae regardless of developmental stage. However, in ABFT the DNA:DW ratio indicated lower condition for the biggest larvae within developmental stages F0 (pre-flexion) and F3 (post-flexion). After removing the size effect, larger individuals of ABFT within flexion stages F1 and F2 had higher condition than any other larval stages, whereas in AB an indistinct trend within stages was found. Our results confirm that in ABFT the RNA:DNA ratio is correlated with faster development while the DNA:DW ratio is negatively correlated with the time to flexion. The trends found in the DNA:DW ratio points at cell growth mechanisms being a better indicator of larval condition that the RNA:DNA ratio. Our findings suggest that under culture, ad libitum conditions, larval nutritional conditions measured by nucleic acid ratios, might not be enough to explain developmental differences in fast growing species.

Efficacy of pirimiphos-methyl, deltamethrin, spinosad and silicoSec against adults and larvae of Tenebrio molitor L. on wheat, barley and maize

The yellow mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae) is a noxious insect that causes serious damages to stored products worldwide. In the present study, pirimiphos-methyl, deltamethrin, spinosad and silicoSec were evaluated as grain protectans against adults, small and large larvae of this species on wheat, barley and maize at label doses. Mortalities were estimated after 1, 3, 7 and 14 days of exposure. All tested insecticides were able to control T. molitor adults. Complete (100%) mortality of adults was noted after 14 days of exposure on wheat and maize treated with pirimiphos-methyl or silicoSec and barley treated with pirimiphos-methyl, silicoSec and spinosad. Larvae were more tolerant than adults to insecticidal treatments. However, pirimiphos-methyl caused high levels of mortality to small larvae that were 71.1, 91.1 and 60% on wheat, barley and maize respectively after 14 days post exposure. The type of commodity played a significant role on the performance of the tested insecticides. Mortality was higher on barley and wheat than on maize for all tested stages and insecticides. Our results indicate that the life stage of T. molitor and the type of commodity should be taken into account for the management of this species.

MIKROHABITAT KATAK TANPA PARU-PARU (Barbourula kalimantanensis Iskandar, 1978) DI KAWASAN TAMAN NASIONAL BUKIT BAKA BUKIT RAYA KABUPATEN MELAWI KALIMANTAN BARAT

Barbourula kalimantanensis is the only frog in Indonesian that has no lungs and only founded in Kalimantan. This study aims to study microhabitat of the lungless frog at Resot Belaban in Bukit Baka Bukit Raya National Park. The method of data collection was done by using Visual Encounter Survey (VES) combining with of tracking systems. The data are taken in 4 observations stations: Ella river 0, Ella river 1, Ella river 2, and Belaban river with tree time repeatly in each station. Based on the result, B.kalimantanensis was found only one specimen in Ella river. The microhabitat of Barbourula kalimantanensis consisted of range air temperature 25˚c – 30˚C, humidity 73% - 95%, water temperature at night ranges from 13º - 14ºC and in the noon 16˚c with a water pH approaching 6.50. The intensity of light entering a location with a large enough amount 125.4 Cd. Dissolved oxygen 7.10 with dissolved solids 7.53 and non-dissolved solids 9. Analysis of water from the four rivers shows that the water in Ella river 0 and Belaban river have pH of water is close to netral pH (7), normal water temperature (27ºC), and the content of dissolved solids and undissolved solids in it. These indicate that the water from both rivers is suitable for humn consumption. The small fish and insect larvae who lived in the river are become a potential prey for B. kalimantanensis. Keywords : Barbourula kalimantanensis, Frog, Herpetofauna, Microhabitat, TNBBBR

Prey detection in antlions: propagation of vibrational signals deep into the sand

AbstractTrap‐building antlion larvae detect their prey according to the substrate vibrations produced during movement of the prey on the sand surface. Although most studies are devoted to surface vibrational waves, in the present study, we determine the role of vibrations travelling through deeper sand layers. A behavioural experiment confirms that vibrational stimuli from prey insects on the surface of the sand stimulate the antlions buried in deeper sand layers to move towards the surface. Sand depth and particle size both have a strong effect on signal transmission. The damping coefficient (α10) varies from 0.49 dB to 3.30 dB cm−1 and depends on frequency (in the range from 100 to 300 Hz), particle size (from finest to coarse sand) and distance from the source of the vibrations. The deeper the sand, the narrower the frequency range of the signal becomes. Sand is a filter for higher frequencies. The smaller the sand particles, the more intense the filtering becomes. Fine sand with a mean sand particle size of 360 μm is a more efficient filter than coarse sand; consequently, high frequencies (&gt; 2.5 kHz) are eliminated at a depth of 3 cm. Mean frequency depends on both depth and particle size. However, low frequency signals still propagate at a certain distance, which is biologically important in prey detection. Although the most efficient signal propagation appears to occur in coarse sand, it contains overly large particles that are inconvenient for relatively small antlion larvae. Predators seek a compromise between fine and coarse sand choosing medium sand.