A pathogenic nonoccluded virus in hemocytes of the navel orangeworm,Amyelois transitella (Pyralidae: Lepidoptera)

A small, nonoccluded virus was isolated from the granular hemocytes (=adipocytes) of moribund larvae of the navel orangeworm, Amyelois transitella, collected from almonds in northern California. The virus was readily transmitted perorally in laboratory tests and was highly pathogenic to neonate larvae; however, third- and fourth-stage larvae usually acquired attenuated infections that retarded growth and delayed mortality. Large paracrystalline viral arrays filled the cytoplasm of granular hemocytes of diseased larvae. Attempts to transmit the virus perorally to larvae of nine other species of moths were unsuccessful. The virus is isometric, about 25 nm in diameter, and contains single-stranded RNA. It has been designated “chronic stunt virus” (CSV) and tentatively assigned to the picorna-like viruses.     

Studies on metabolism of lung flukes of the genus Paragonimus. VI. Succinoxidase system in homogenates of eggs, larvae, and adults

The present study was concerned with the succinoxidase system in Paragonimus westermani, Paragonimus ohirai, and Paragonimus miyazakii. Potassium cyanide inhibited the motility of larval and adult forms. Succinate stimulated the reduction of methylene blue by homogenates of embryonated eggs, larvae, and adults, while malonate inhibited the reduction. Reduced cytochrome c was oxidized by the 1,000g supernatant from homogenates of embryonated eggs, larvae, and adults. The supernatant prepared from unembryonated eggs did not oxidize reduced cytochrome c. Succinate stimulated oxygen consumption by the homogenate of adult worms. Oxygen consumption markedly increased in the homogenate of adults when both succinate and cytochrome c were added as substrate to the reaction mixture, while malonate and cyanide inhibited oxygen consumption.     

Susceptibility of the Mediterranean fruit fly (Ceratitis capitata) and the Natal fruit fly (Ceratitis rosa) to entomopathogenic nematodes

The potential of entomopathogenic nematodes, Heterorhabditis bacteriophora, Heterorhabditis zealandica and Steinernema khoisanae, to infect pupariating larvae, pupae and adults of Ceratitis capitata and Ceratitis rosa was investigated in laboratory bioassays. Pupariating larvae and adult flies were susceptible to nematode infection, with no infection recorded for the pupae. Pupariating larvae of C. capitata were generally more susceptible to infection than those of C. rosa. Significantly more larvae of C. capitata were infected by H. bacteriophora. For C. rosa, highest infectivity of larvae was obtained with H. zealandica. In contrast, adults of both species were highly infected by S. khoisanae.     

Susceptibility of the Plum Curculio,Conotrachelus nenuphar,to Entomopathogenic Nematodes

The plum curculio, Conotrachelus nenuphar, is a major pest of pome and stone fruit. Our objective was to determine virulence and reproductive potential of six commercially available nematode species in C. nenuphar larvae and adults. Nematodes tested were Heterorhabditis bacteriophora (Hb strain), H. marelatus (Point Reyes strains), H. megidis (UK211 strain), Steinernema riobrave (355 strain), S. carpocapsae (All strain), and S. feltiae (SN strain). Survival of C. nenuphar larvae treated with S. feltiae and S. riobrave, and survival of adults treated with S. carpocapsae and S. riobrave, was reduced relative to non-treated insects. Other nematode treatments were not different from the control. Conotrachelus nenuphar larvae were more susceptible to S. feltiae infection than were adults, but for other nematode species there was no significant insect-stage effect. Reproduction in C. nenuphar was greatest for H. marelatus, which produced approximately 10,000 nematodes in larvae and 5,500 in adults. Other nematodes produced approximately 1,000 to 3,700 infective juveniles per C. nenuphar with no significant differences among nematode species or insect stages. We conclude that S. carpocapsae or S. riobrave appears to have the most potential for controlling adults, whereas S. feltiae or S. riobrave appears to have the most potential for larval control.     

Effect of surface potential on Rb+ uptake in yeast: The effect of pH

The apparent K_m of Rb⁺ uptake and the zeta potential of yeast cells are appreciably affected by changes in the pH, variation of the concentration of the buffer cation Tris⁺ and addition of Ca²⁺ to the suspending medium. Irrespective of the way in which the zeta potential is affected, a direct relationship between the apparent K_m of the Rb⁺ uptake and the zeta potential is observed. A reduction of 8 mV in the zeta potential is accompanied by a 20-fold increase in the apparent K_m, which illustrates that electrostatic effects in ion uptake cannot be ignored. Measured zeta potentials are, to a good approximation, linearly related to surface potentials evaluated from a kinetic analysis of the Rb⁺ uptake. This shows the practical use of the zeta potential as a measure of the surface potential in studies of electrostatic effects in ion uptake by yeast. It is concluded that Tris⁺ and the aikaline earth cations inhibit the Rb⁺ uptake in yeast exclusively via a reduction in the surface potential. Protons, in addition, exert a competitive inhibition.     

Low temperature shock and chill-coma consequences for the red flour beetle (Tribolium castaneum) and the rice weevil (Sitophilus oryzae)

Insects face several (environmental) abiotic stressors, including low temperature, which cause the failure of neuromuscular function. Such exposure leads insects toa reversible comatose state termed chill-coma, but the consequences of this state for the organism biology were little explored. Here, the consequences of the chill-coma phase were investigated in two of the main stored product pest species – the red flour beetle Tribolium castaneum (larvae and adults) and the rice weevil Sitophilus oryzae (adults). For this purpose, a series of low-temperature shocks were used to estimate the chill-coma recovery time (CCRT), survival, nutrition and weight gain/growth of T. castaneum (larvae and adults) and S. oryzae, as well as the development of T. castaneum life stages. The relatively long CCRT was characteristic of beetle larvae, at different low-temperature shocks, and CCRT increased with decreasing temperatures and increasing exposure intervals for both pest species. The survival was little affected by the low-temperature shocks applied, but such shocks affected insect feeding and growth. Tribolium castaneum larvae was more sensitive than adults of both insect species. Moreover, the relative consumption and weight gain of S. oryzae adults were lower than those of T. castaneum adults and mainly larvae, while feeding deterrence was not affected by low temperature shocks, unlike food conversion efficiency. Low-temperature shocks, even under short duration at some temperatures, significantly delayed development. The lower the temperature and the higher the exposure period, the more delayed the development. Thus, the physiological costs of chill-coma are translated into life-history consequences, with potential implications for the management of this insect pest species in stored products and even more so on red flour beetles and rice weevils.     

Trichinella spiralis: Rapid,immunologically influenced reduction of intestinal,sodium-coupled sugar transport in the rat

Epithelium of isolated small intestinal segments were studied in Ussing-type chambers to detect physiological changes associated with rapid, immune rejection of Trichinella spiralis infective larvae. Electrophysiological parameters associated with Na⁺-coupled hexose transport were measured. Changes in transepithelial electrical potential difference (PD), resistance, and short circuit current (I_sc) due to the addition of actively absorbed β-methyl-d-glucoside (BMG) to the mucosal solution were determined. Measurements were made prior to and 30 min after primary and secondary infections. Animals were infected by intraduodenal inoculation. As the infective larval dose in primarily infected (nonimmunized) rats increased from 50 to 2000 larvae the magnitude of the rise in I_sc elicited by BMG decreased in a dose-dependent fashion, with 50 larvae per rat having no effect. In previously infected (immunized) rats challenged with a secondary inoculum, all doses, ranging from 50 to 2000 larvae per rat, decreased the BMG-stimulated change in I_sc by approximately 50%. The effect of 50 worms per rat in immunized hosts was equivalent to that produced by ~1600 worms in nonimmunized animals. Measurements of ¹⁴C-BMG mucosa-to-serosa flux confirmed that Na⁺-BMG cotransport was responsible for observed changes in I_sc. Results support the conclusion that changes in intestinal epithelial function are associated with larval challenge of immune rats.     

Number of Malpighian Tubules in Larvae and Adults of Stingless Bees (Hymenoptera: Apidae) from Amazonia

The number of Malpighian tubules in larvae and adults of bees is variable. Larvae of Apis mellifera L. have four Malpighian tubules, while adults have 100 tubules. In stingless bees, this number varies from four to eight. The objectives of this study were to provide characteristics of the Malpighian tubules as well as to quantify their number in larvae and adults of six species of Meliponinae, Melipona seminigra merrillae Cockerell, Melipona compressipes manaosensis Schwarz, Melipona rufiventris Lepeletier, Scaptotrigona Moure, Frieseomelitta Ihering, and Trigona williana Friese. Malpighian tubules were dissected from larvae and adults, measured, quantified, and maintained in microtubes with Dietrich??s solution. The numbers of Malpighian tubules were constant only for larvae of M. rufiventris (four and eight) and Scaptotrigona sp. (four). The most frequent number of tubules in the Melipona group was seven and eight in larvae, and 70 and 90 in adults. In the Trigona group were four and 20 to 40, for larvae and adults, respectively. The results showed differences in the number of Malpighian tubules among the species analyzed and also between the larvae and adults of the same species. Despite the variation observed, species of the group Melipona always have a larger number and longer Malpighian tubules in both larvae and adults as compared to the Trigona group, which may indicate an evolutionary trend of differentiation between these groups.     

Susceptibility of the Colorado Potato Beetle and the Sugarbeet Wireworm to Steinernema feltiae and S. glaseri

In laboratory tests, larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and the sugarbeet wireworm (SBW), Limonius californicus (Mannerheim), were exposed to the nematodes Steinernema feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm² of soil, and the LC₅₀ based on 6-day mortality was 47.5 nematodes/cm²; in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm². CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm² soil caused 59% and 71% mortality, respectively, of late-fourth-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 weeks after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.     

In vitro culture of hymenopterous larval endoparasitoids

The solitary endoparasitoids Cotesia (= Apanteles) marginiventris and Microplitis croceipes, which attack noctuid larvae, were successfully cultured from post-germband stage eggs to fully grown first-instar larvae in completely artificial (but undefined) media. However, growth rates were slower than in vivo, and while some larvae of each species attained apparent competence to moult (based upon characteristic size and form), none did so.Up to 75% of pregermband M. croceipes eggs developed and hatched when co-cultured with fat body from non-parasitized larvae of the habitual host, Heliothis zea. Heat-treated haemolymph plasma from a non-permissive host, Manduca sexta, also fostered development by ca. 40% of newly laid M. croceipes eggs, but plasma from H. zea larvae was not beneficial. Growth rates of C. marginiventris and M. croceipes larvae were not improved by haemolymph plasma from their habitual hosts (Spodoptera frugiperda and H. zea, respectively).Heat-treated foetal bovine serum was growth-promoting for post-germband eggs and larvae of both parasitoids. Treatment of foetal bovine serum by charcoal adsorption (to remove sterols and peptide hormones) diminished its value as a supplement. Two major proteins of the serum, foetuin and albumin, also promoted survival and growth for both parasitoid species. The potential relevance of these findings to in vitro rearing of endoparasitoids is discussed.     

The distribution of entomophilic nematodes (Heterorhabditidae and Steinernematidae) in North Carolina

Over 500 samples of soil from cropland, vineyards, orchards, pasture, and forest habitats throughout North Carolina were tested for the presence of steinernematid and heterorhabditid nematodes by baiting with Galleria mellonella larvae. Nematodes were isolated from 13 of 14 locations and from each habitat. Heterorhabditids (Heterohabditis heliothidis) were most commonly found (13 locations) with Steinernema (= Neoaplectana) glaseri, S. feltiae (= Neoaplectana carpocapsae), and an undescribed Steinernema species being found at one or two locations. The primary form of the bacterial symbiont of S. glaseri was isolated for the first time.     

What does not kill them makes them stronger: larval environment and infectious dose alter mosquito potential to transmit filarial worms

For organisms with complex life cycles, larval environments can modify adult phenotypes. For mosquitoes and other vectors, when physiological impacts of stressors acting on larvae carry over into the adult stage they may interact with infectious dose of a vector-borne pathogen, producing a range of phenotypes for vector potential. Investigation of impacts of a common source of stress, larval crowding and intraspecific competition, on adult vector interactions with pathogens may increase our understanding of the dynamics of pathogen transmission by mosquito vectors. Using Aedes aegypti and the nematode parasite Brugia pahangi, we demonstrate dose dependency of fitness effects of B. pahangi infection on the mosquito, as well as interactions between competitive stress among larvae and infectious dose for resulting adults that affect the physiological and functional ability of mosquitoes to act as vectors. Contrary to results from studies on mosquito–arbovirus interactions, our results suggest that adults from crowded larvae may limit infection better than do adults from uncrowded controls, and that mosquitoes from high-quality larval environments are more physiologically and functionally capable vectors of B. pahangi. Our results provide another example of how the larval environment can have profound effects on vector potential of resulting adults.     

Bt maize fed-prey mediated effect on fitness and digestive physiology of the ground predator Poecilus cupreus L. (Coleoptera: Carabidae)

We investigated the effects of a Bt maize hybrid on fitness and digestive physiology of the ground-dwelling predator Poecilus cupreus L., as compared with the near-isogenic hybrid. A tritrophic assay revealed that there was a great decline in the detection of Cry1Ab toxin through the trophic chain, the concentration of the toxin being 945, 349 and 37 ng g⁻¹ of fresh weight in Bt maize leaves, Spodoptera littoralis (Boisduval) larvae and P. cupreus larvae, respectively. Moreover, the toxin was only detected in 8% of the P. cupreus adults collected from fields growing Bt maize. Developmental time of both larvae and pupae of P. cupreus was not adversely affected by the Cry1Ab toxin via fed-prey. To elucidate potential detrimental effects due to a reduction in the quality of the prey, we assessed the digestive proteolytic activities of P. cupreus adults from a laboratory culture and insects collected in commercial Bt and non-Bt maize fields. Field-collected P. cupreus adults had higher proteolytic activities than those reared in the laboratory, whereas no significant differences were found between P. cupreus adults reared on Bt and non-Bt maize fed-S. littoralis or between P. cupreus adults collected in commercial Bt and non-Bt maize fields.     

Olfactory responses of Grapholita molesta to different developmental stages of immature fruit of peach,plum, and apple

The Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is known to shift its host use from stone fruits (the primary hosts) to pome fruits (secondary hosts) as the season progresses. Grapholita molesta recognizes potential hosts by semiochemicals from fruits, but few studies have addressed the olfactory responses of G. molesta to host fruits during the seasonal transition of the moth from stone to pome fruits. So, we investigated the olfactory responses of larvae and gravid females of G. molesta to different fruit stages (collected on May 31, June 11, and June 25) of immature peach, plum, and apple fruits, using both multiple and two choice tests. In the multiple choice tests, for fruits collected after June 11, larvae showed a significant preference for peach as their first choice, compared to plum or apple. The final choice rate (when larvae had stayed on the fruit for more than 1 h) of larvae was also highest for peach fruits collected on June 11 and June 25. In two choice tests (Y-tube test), the response rate and overall choice rate of larvae and mated ovipositing adult females were also highest on peaches collected on May 31 (larvae) and June 25 (adults), respectively. In conclusion, we found that both the adults and larvae of G. molesta were highly attracted to immature peach fruits in laboratory choice tests.     

Prey instar preference and functional responses of Mallada basalis (Walker) (Neuroptera: Chrysopidae) to different life stages of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae)

Prey instar preference and functional responses of 2- and 3-instar Mallada basalis (Walker) (Neuroptera: Chrysopidae) larvae to 1- to 3-instar Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) nymphs and adults were assessed in laboratory. Results indicated that both 2- and 3-instar M. basalis larvae preferred young over old P. solenopsis nymphs and adults were the least preferred. The 3-instar M. basalis larvae preyed more adult P. solenopsis than 2-instar larvae. Mallada basalis exhibited type II functional responses to prey densities: An increase in prey density leads to an increase in consumed preys. Regardless of P. solenopsis stages, the number of preys consumed by the 3-instar M. basalis larvae was greater than that by the 2-instar larvae. Attack rates and handling times differed depending on prey and predator stage combinations. The highest attack rate (1.1874) and lowest handling time (0.0040 h) were observed for the 3-instar M. basalis larvae fed on the 1-instar P. solenopsis nymphs. Regardless of P. solenopsis stages, the attack rate of 3-instar M. basalis was greater than 2-instar, whereas the reverse held regarding handling time. The findings collectively indicated that 3-instar M. basalis larvae have greater potential than 2-instar as efficient biological control agent of P. solenopsis. In developing real world biological control programs, however, the 2-instar M. basalis may be released if necessary since the final efficacy of the predator is the summation of the 2- and 3-instar M. basalis.     

The larva of Eustra (Coleoptera, Paussinae, Ozaenini):a facultative associate of ants

Larvae of the ground beetle genus Eustra Schmidt-Goebel are described and illustrated for the first time and some biological notes are reported. One specimen of an unknown Eustra species was collected while excavating a nest of the ant Pachycondyla javana Mayr, in Taiwan, which is the first report of a paussine associated with a member of the ant subfamily Ponerinae. Several larvae and adults of a second species, Eustra chinensis Bänninger, were collected in Shanghai under bark with no association with ants. First instar larvae of the latter species were also reared in the lab. The occurrence of larvae of the genus Eustra both inside and outside ant nests, together with a report of adults collected inside a nest in Taiwan, suggests that members of this genus may be facultative predators or facultative symbionts of ants, an attribute that has never been reported for this genus. The larvae of Eustra show several unique features, including a peculiar bidentate mandibular apex, an extremely long galea, one of two tarsal claws greatly reduced, abdominal setae (including those of terminal disk) elongate and clavate at apex, urogomphi wide and flattened, and inflated sensilla S-I. Larvae were studied by both optical and scanning electron microscopy, their morphological features are compared with those of other described Paussinae larvae, and their potential phylogenetic and functional significance are discussed.     

Nutrient reserves in starving black carpet beetle larvae infected with the eugregarine Pyxinia frenzeli

Starvation-mediated alterations of nutrient reserves (lipid, protein, glycogen) of larvae of the black carpet beetle, Attagenus megatoma (=Attagenus piceus), were studied. Quantitative comparisons of these materials between uninfected larvae and those infected with the eugregarine Pyxinia frenzeli were performed in an effort to characterize pathologic conditions elicited by the gregarine. Fresh weight losses were similar in both types of insects; however, infected larvae had a consistently higher moisture content. No differences were detected in the rate of utilization of stored protein, glycogen, or lipid. These data provide evidence that P. frenzeli is a commensal or mutualist, rather than a pathogen.     

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) eggs as alternative food for rearing of lady beetles Eriopis connexa (Germar) (Coleoptera: Coccinellidae)

Eriopis connexa (Germar) (Coleoptera: Coccinellidae) is an important predator with potential for biological control of insect pests. This research evaluated the development of E. connexa larvae fed on fresh eggs of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) without (T1) or with (T2) scales or one-day (T3) or six-month (T4) frozen, or newly-hatched larvae of S. frugiperda (T5). The percentage of E. connexa adults was higher when larvae feeding on fresh S. frugiperda eggs with or without scales, or one-day frozen eggs of this prey and lower with eggs of this Lepidoptera after frozen for six months or with newly-hatched larvae of S. frugiperda. Duration of the larval period of E. connexa was 15.7, 15.8, 16.0, 17.6, and 17.3 days, respectively, with these diets. The high survival of E. connexa fed with eggs of S. frugiperda shows the potential use of this prey in the laboratory to maintain this natural enemy.     

Oxidation-reduction potentials and spectral properties of some cytochromes from Thiobacillus versutus (A2)

Cytochromes c-550 (acidic), c-550 (basic), c-551 and c-552.5 from Thiobacillus versutus have been highly purified and characterized. Their spectral properties at 77 K are described. Oxidation-reduction titrations of cytochromes c-550 (acidic) and c-550 (basic) showed them to exhibit Nernst values of n = 1, with single redox centres in the cytochromes, and to have midpoint redox potentials at pH 7.0 (E_m,7) of 290 and 260 mV, respectively. Cytochrome c-551 contained two separately titratable redox components, each giving n = 1. The low potential centre (55% of titratable cytochrome) and the high potential centre (45%) had E_m,7 values of ?115 and +240 mV, espectively. Cytochrome c-552.5 also contained at least two redox centres. One (65% of titratable cytochrome) had n = 1 and E_m,7 = 220mV. The remaining 35% appeared to be a low potential component with an E_m,7 possibly as low as ?215 mV. the roles of these cytochromes in respiratory thiosulphate oxidation are discussed.     

“Smerdis” glangeaudi Priem (poisson téléostéen), espèce mythique du Stampien des environs de Corent (Puy-de-Dome)

The mythical character of the species «Smerdis glangeaudiPriem is demonstrated, using mainly lithological, anatomical, morphometrical and field arguments. In fact, this species has been described from a composite hypodigm which truly includes two specimens of Dapalis (=Smerdis) macrurus (Ag.) from the neighbourhood of Céreste (Alpes de Haute-Provence) and another one of Dapalis (=Smerdis) minutus (Bl.) from the ancient gypsum quarries of Aix-en-Provence.