Climate and the effectiveness of Psyllaephagus bliteus as a parasitoid of the red gum lerp psyllid

The encyrtid parasitoid Psyllaephagus bliteus Riek was introduced to California in 2000 to control the red gum lerp psyllid, Glycaspis brimblecombei Moore. Field experiments were conducted to determine the effect of regional summer climate (California coastal vs. interior valleys) on P. bliteus performance. Measurements of parasitoid performance, including reproduction and longevity, showed that P. bliteus was adversely affected by the extreme summer heat in the interior valley sites. The results suggest that regional climatic differences can contribute to the lower parasitism rates observed in California's warmer interior valleys. The results are discussed with respect to biological control of G. brimblecombei and the potential limitations of the parasitoid P. bliteus, as well as the possible impact of climate and intraguild predation as alternative hypotheses for the observed variable geographic performance of P. bliteus.     

Host suitability and fitness-related parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae) as a parasitoid of the cabbage looper,Trichoplusia ni (Lepidoptera: Noctuidae)

The seven age-classes of Trichoplusia ni (Hübner) larvae evaluated in this study as hosts of Campoletis sonorensis indicates that early 2nd larval instar (3–5 day-old larvae) of T. ni represents the most suitable host stage for the development of the larval endoparasitoid C. sonorensis. The higher suitability of early 2nd larval instar of T. ni resulted in more parasitised larvae, a higher rate of successful parasitoid emergence, a higher rate of female progeny, and a lower rate of immature parasitoid mortality. The fitness gain of C. sonorensis on late 1st larval instar (2 day-old larvae) and late 2nd larval instar –early 3rd instars (6–8 day-old larvae) stages of T. ni is negatively affected by the trade-offs between the different physiological and behavioral characteristics influencing their suitability as hosts of C. sonorensis.     

Biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of carob moth Ectomyelais ceratoniae (Lepidoptera: Pyralidae)

The carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae), is the most important pest of pomegranate orchards (in terms of economic damage) within Iran, and hence, several control procedures, including biological methods of control, have been attempted as a means of controlling populations of this insect. This research was carried out in order to study the biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of the carob moth. Laboratory studies were conducted to determine larval developmental time, adult longevity, sex ratio, parasite progeny production, and host stage preference of A. myeloenta. At 25 ± 1 °C, immature developmental time (egg to pupa; mean ± SE) was 28.33 ± 0.85 days and 27.46 ± 0.37 days for male and females, respectively. Adult females survived on average 17.5 ± 0.14, 11.7 ± 0.22, 3.4 ± 0.18, and 2.8 ± 0.12 days at 25 C when provided with honey and water, honey only, water only or no food source, respectively. The sex ratio (females to males) of A. myeloenta was 1:3.5 from hosts parasitized in the first instar, 1:3 for second instars and 1:2 for third instar carob moth larvae. Female A. myeloenta typically preferred to parasitize second instar over third or first instar. The oviposition activity peaked on the 7th and 8th days following emergence, when provided with honey, and 10% sucrose solution, respectively.     

Food consumption,utilization and ecological efficiency of Parthenium beetle,Zygogramma bicolorata pallister (Coleoptera: Chrysomelidae)

Food consumption, utilization and ecological efficiency of Zygogramma bicolorata were studied in larvae and adults up to 45 days old. The study revealed that sex had a significant influence on dry food consumption in adults but not in larvae. The other parameters of ecological efficiencies, viz. efficiency of conversion of ingested food (E.C.I.), tissue growth and dry biomass, were highest in the fourth instar and in adult females. The Consumption Index (C.I.) was higher in males than females in both larval and adult stages. Developmental and growth rates were relatively higher in the first and second instars. The fourth instar and adult females were the most efficient consumers and converters of food. Food intake by females was an important determinant of the number of eggs laid.     

Entomotoxic properties of Dioclea violacea lectin and its effects on digestive enzymes of Anagasta kuehniella (Lepidoptera)

Entomotoxic plant lectins have been extensively studied in the past two decades, yet the exact mechanisms underlying their toxic effects remain unknown. This study investigated the effects of Dioclea violacea lectin (DVL) on larval development in Anagasta kuehniella. Chronic exposure of larvae (from neonates to the fourth instar) demonstrated that DVL interfered with larval growth, retarding development and decreasing larval mass without affecting survival. DVL decreased trypsin-like, chymotrypsin-like, and α-amylase activities and proved resistant to proteolysis by midgut proteases up to 24 h. Shorter exposures to dietary DVL had no effect on midgut enzyme activity. Feeding fourth-instar larvae with fluorescently-labeled DVL revealed lectin binding to the peritrophic membrane.     

Age-specific digestion of Tenebrio molitor (Coleoptera: Tenebrionidae) and inhibition of proteolytic and amylolytic activity by plant proteinaceous seed extracts

Tenebrio molitor L. (Coleoptera: Tenebrionidae), is an international and serious pest of stored products. So far nothing is known about the activity for each growth stage digestive enzyme regarding this insect species. Thus, the aim of the current study was to get in depth analysis of the stage specific digestion and to investigate the effect of cereal (wheat cultivars including MV17, Aflak, Sivand, Saymon, and Zare) and legume (bean) seed extracts on the two main digestive enzymes i.e. α-amylases and proteases. Therefore, gut enzymes were extracted using distilled water and wheat cultivars and bean seed proteinaceous compounds were extracted using 0.1 M NaCl. Results showed that a steady state increase in the number and amount of digestive enzyme activities from first to fourth instar larvae was seen in both enzyme and in gel assays. In the first instar larvae (L1) only one band of α-amylase activity was seen (A1), whereas in the second (L2), third (L3), fourth (L4) and fifth (L5) instar larvae as well as in the adult (A) more than one amylase band (up to 4 isoenzymes) was seen. The same pattern was observed for α and β glucosidases and proteases. Probit analysis showed that bean and MV17 inhibited the amylase activity with an I₅₀ of 9.73 and 7.4 μg, respectively. The same cultivar seed extract inhibited protease activity with I₅₀s of 11.54 and 6.5 μg proteins. It is concluded that proteinaceous extract of cereals and bean seeds have a strong potential to be used in this pest management.     

The endophytic fungal entomopathogens Beauveria bassiana and Purpureocillium lilacinum enhance the growth of cultivated cotton (Gossypium hirsutum) and negatively affect survival of the cotton bollworm (Helicoverpa zea)

The effects of two entomopathogenic fungal endophytes, Beauveria bassiana and Purpureocillium lilacinum, were assessed on the growth of cultivated cotton (Gossypium hirsutum) and development of the cotton bollworm (Helicoverpa zea). In two replicate greenhouse trials, cotton plants were inoculated as seed treatments with two concentrations of B. bassiana or P. lilacinum conidia and evaluated for effects on both plant dry biomass, number of nodes and number of developing flowers (squares). We similarly treated cotton plants and evaluated H. zea performance using no-choice in planta assays starting at the 2nd larval instar. Treatment with both fungal endophytes resulted in a significant increases in plant dry biomass (ANOVA, P = 0.024). Plant developmental stage and number of squares were also significantly enhanced in the endophyte treated plants (ANOVA, P = 0.005 and P = 0.027, respectively). The survivorship of H. zea was significantly different among the endophyte treatment groups (Kaplan–Meier, P = 0.02), where insects feeding on control plants exhibited higher survival than insects on the endophyte treated plants. There were no significant endophyte treatment effects on larval or pupal weights of H. zea individuals. There was no endophyte effect on days to pupation among treatments, but there was a marginal effect on days to eclosion (Kaplan–Meier, P = 0.07). Overall, our results demonstrate (i) the positive plant growth enhancing effects of the target endophyes on cultivated cotton under greenhouse conditions and (ii) the negative effects of endophytic P. lilacinum and B. bassiana on H. zea survivorship and development using whole plant assays.     

Laboratory and semi-field evaluation of Beauveria bassiana (Ascomycota: Hypocreales) against the lettuce aphid,Nasonovia ribisnigri (Hemiptera: Aphididae)

The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. The entomopathogenic fungus Beauveria bassiana strain GHA has recently been reported as a potential biocontrol candidate for use against the lettuce aphid. This study provides information on the mortality inflicted by B. bassiana when applied against different life stages of the lettuce aphid under laboratory conditions and how fungus infection affects the aphid fecundity. In addition, temporal changes in persistence of fungus inoculum applied to foliage of young lettuce plants under semi-field conditions was analysed. Immature life stages were generally the least susceptible to fungal infection and the susceptibility of all stages was dose-dependent, with the highest mortality occurring at the highest dose. B. bassiana significantly affected the rate of nymph production by the lettuce aphid, with the highest effect seen when the alatoid fourth instar of N. ribisnigri was inoculated with B. bassiana. The persistence of B. bassiana conidia on lettuce foliage was not influenced by leaf position. Within 5 days, the cumulative percentage decline in the conidial population was 38% which declined further to 92% and 99% on day 11 and 20 post-spraying, respectively. In accordance, the infectivity to second instar lettuce aphid nymphs of B. bassiana conidia deposited on leaves declined according to an exponential decay model predicting an intercept of 0.59 ± 0.03 (S.E), a reduction in aphid mortality at a rate of 11% with each increasing day after fungal application and a fungus half-life of 6.34 ± 0.69 days.     

Aedes aegypti midgut remodeling during metamorphosis

The Aedes aegypti midgut is restructured during metamorphosis; its epithelium is renewed by replacing the digestive and endocrine cells through stem or regenerative cell differentiation. Shortly after pupation (white pupae) begins, the larval digestive cells are histolized and show signs of degeneration, such as autophagic vacuoles and disintegrating microvilli. Simultaneously, differentiating cells derived from larval stem cells form an electron-dense layer that is visible 24 h after pupation begins. Forty-eight hours after pupation onset, the differentiating cells yield an electron-lucent cytoplasm rich in microvilli and organelles. Dividing stem cells were observed in the fourth instar larvae and during the first 24 h of pupation, which suggests that stem cells proliferate at the end of the larval period and during pupation. This study discusses various aspects of the changes during midgut remodeling for pupating A. aegypti.     

Aspects of the reproductive biology of Pseudaphycus maculipennis (Hym: Encyrtidae), a parasitoid of obscure mealybug,Pseudococcus viburni (Hem: Pseudococcidae)

Laboratory experiments to determine aspects of the reproductive biology of Pseudaphycus maculipennis are described. All experiments were carried out at a constant temperature of 21 ± 2 °C, a 16-h photoperiod and ambient RH. Pseudaphycus maculipennis was shown to be an arrhenotokous, synovigenic, gregarious endoparasitoid of Pseudococcus viburni. Females and males lived for 16 and 11 days, respectively, when fed either honey-agar or mealybug honeydew. Relatively, large instars (third instar or adult females) were preferred for oviposition; mated females parasitized more mealybugs than unmated females, and the progeny sex ratio favored females by 3:1. Egg load increased with age from emergence to day 8, averaging 23 mature eggs/female. Mean realised daily fecundity never exceeded 5, with a mean lifetime fecundity of 46 eggs/female. Parasitised mealybugs remained alive for about 5 days and then mummified. Total development period was 20–21 days (larva 4–5 days, prepupa 3 days, pupa 8–9 days). Development periods of eggs and individual larval instars were not measured. A mean of 3.01 ± 0.1 parasitoids/mealybug were reared after individual parasitism events, increasing through super-parasitism (either self or conspecific) to 9 parasitoids/mealybug when hosts were exposed to competing females. Pseudaphycus maculipennis progeny emerged from the mummies in discrete cohorts over periods ranging from 3 min to 18 h (depending on the number of cohorts).     

Toxicity of Acalypha indica (Euphorbiaceae) and Achyranthes aspera (Amaranthaceae) leaf extracts to Aedes aegypti (Diptera: Culicidae)

Alternative control strategies for the dengue vector Aedes aegypti L. (Diptera: Culicidae) include botanical insecticides. They are believed to pose little threat to the environment or to human health and may provide practical substitutes for synthetic insecticides. In this study, we determined the biological activities of methanol extracts of Acalypha indica L. (Euphorbiaceae) and Achyranthes aspera L (Amaranthaceae) leaves individually and in combination as botanical insecticides against Ae. aegypti. Based on LC₅₀ values for 4th instar Ae. aegypti, the combined extracts showed the strongest larvicidal activity (277 ppm). A. aspera and A. indica extracts individually gave similar results (409 and 420 ppm, respectively). Respective LC₅₀ values for pupae were 326 ppm, 456 ppm, and 467 ppm. In studies of smoke toxicity, 64% of females exposed to negative control smoke (no extract) blood fed on chicken, whereas 17% blood fed when exposed to smoke containing A. aspera extract and to positive control smoke (0.2% d-allethrin). In the field, treatment of water storage tanks (≈ 0.5 m³) with combined plant extract reduced larval and pupal populations by 97% and 81%, respectively, after 5 days. Given the results of this study, further evaluation of the combined (A. indica + A. aspera) extract as a mosquito larvicide is warranted. Mosquito coils with A. aspera extract also show promise as a practical and potentially economical means for mitigating mosquito blood feeding.     

Molecular identification of glucose-regulated protein 78 (grp78) gene from the Indian meal moth,Plodia interpunctella,and its regulation by nutrient uptake

Glucose-regulated protein 78 (GRP78) is a member of the HSP70 family of proteins and is localized in the endoplasmic reticulum (ER) within cells. GRP78 and its gene has been identified in only a few species of insects, and its role is not clear. Here, we identified full-length grp78 cDNA from the Indian meal moth, Plodia interpunctella, and demonstrated the role of grp78 in developmental and physiological processes of the insect. The deduced amino acid sequence of GRP78 contained highly conserved functional motifs of the HSP70 family and the C-terminal motif of KDEL, which is characteristic of ER-localized HSP70. It also showed high identity (93–94%) with GRP78 and related HSP70 proteins of lepidopteran species. Gene expression analysis showed that grp78 mRNA levels were high in the egg, feeding larval, and adult stages, but low in the molting, wandering larval, and pupal stages of development. In a tissue comparison of fifth instar P. interpunctella, grp78 level was higher in the gut than in the integument or fat bodies. Grp78 level decreased greatly when fifth-instar larvae were starved for 48 h, but recovered within 3–6 h after re-feeding. Our data suggest that grp78 is highly associated with dietary energy conditions during development and may play an important role in the nutritional physiology of insects.     

Establishment of <Emphasis Type="Italic">Psyllaephagus parvus</Emphasis> and <Emphasis Type="Italic">P. perplexans</Emphasis> as serendipitous biological control agents of Eucalyptus psyllids in southern California

The free-living lemon gum psyllid, Cryptoneossa triangula Taylor, and the lerp-forming spotted gum psyllid, Eucalyptolyma maideni Froggatt (Hemiptera: Psyllidae) are invasive pests of eucalypts in California. In 2007, Psyllaephagus parvus Riek (Hymenoptera: Encyrtidae) was discovered parasitizing spotted gum psyllids and Psyllaephagus perplexans Cockerell was collected from lemon gum psyllids. While neither parasitoid species was purposely introduced, presence of the parasitoids was significantly associated with reduced intensity and duration of population peaks for both psyllid species. Spring peaks were reduced more than fall peaks. We estimated minimum rates of parasitism from the ratio of mummies to live nymphs. Higher parasitism was recorded in coastal than inland locations during the spring, while parasitism was similar for coastal and inland populations in the fall. Logistic regression models suggest parasitoids were the determining factor of psyllid population densities, although physical parameters, such as irrigation, may affect psyllid or parasitoid populations.     

Life cycle of the aquatic firefly Luciola ficta (Coleoptera: Lampyridae)

This research is the first to record the complete life history of the aquatic firefly Luciola ficta (Olivier) using a unique individual rearing method. Transparent containers (250 ml; height: 6 cm; bottom diameter: 8 cm; mouth diameter: 9.5 cm) were used to rear individuals from egg to adult in the laboratory, so that they could be observed throughout the whole life cycle. Larvae were fed on the meat of the water snail Cipangopaludina chinensis (Gray). Temperature ranged from 18 °C to 30 °C, relative humidity (RH) was 80 ± 5%, and the light:dark (L:D) ratio was 10:14. Of 80 eggs, 35 individuals completed their life cycle under these laboratory conditions in Jiji, Nantou County, Taiwan. The external morphological characteristics of each growing stage were described. Egg hatching rate was 95%. On average, one generation spanned 388.2 ± 25.7 days. The durations of egg, larva, climbing larva, cocoon, and adult stages were 19.1 ± 1.5 days, 328.9 ± 33.2 days, 10.9 ± 7.8 days, 14.7 ± 5.3 days, and 15.7 ± 5.2 days, respectively. The number of larval instars ranged from five to seven, with a modal value of six instars for males and seven instars for females. Female larval duration averaged 337.1 ± 31.2 days, which was higher than the 307.6 ± 34.1 days of the males. From January to December 2002, adult emergence peaked twice, with the main high peak appearing in April and the second peak occurring in August. The results of indoor rearing and of field investigations in Jiji, Nantou County, suggested that L. ficta is univoltine. Adult body length is negatively correlated with larval duration (P < 0.01). The life history traits of L. ficta show plasticity in adult occurrence, egg size, egg duration, larval duration, larval instars, and adult body length. Some variations were discussed in the context of survivorship in field habitats.     

Evaluation of Metarhizium anisopliae strains as potential biocontrol agents of the tick Rhipicephalus (Boophilus) microplus and the cotton stainer Dysdercus peruvianus

The negative aspects of traditional pest control have led to the investigation of alternative methods such as biological control. Metarhizium anisopliae, well known as an entomopathogenic fungus capable of actively invading and killing its hosts and thus a candidate biopesticide, is here tested against two agricultural pests of economic/social importance and also evaluated for its chitinolytic secretion and capacity to grow and sporulate at different temperatures. None of the isolates was able to grow below 4 °C or above 37 °C. Chitinolytic activity under artificial growth conditions revealed that Rhipicephalus (Boophilus) microplus cuticle induces N-acetyl-β-d-glucosaminidase and endochitinase activities more efficiently than Dysdercus peruvianus cuticle and that glucose did not repress those activities. Bioassays were carried out with R. microplus females and fourth instar D. peruvianus. Six isolates of M. anisopliae were pathogenic to the engorged female cattle ticks. E6, GC47 and CG97 were the most virulent isolates for both arthropod models although differences were seen among them. M. anisopliae strains caused 90–100 % mortality on the fourth post-infection day in R. microplus. D. peruvianus females were more sensitive to fungal infection than males, and the most virulent strains caused 50 % mortality on the third to fourth day post-infection. Our studies suggest that M. anisopliae strain CG47 is a candidate for commercial pesticide formulations due to its capacity to kill both hosts and its ability to sporulate at higher temperatures.     

A new method to study the functional response of Scymnus syriacus (Coleoptera: Coccinellidae) to different densities of Aphis gossypii

Functional response is basic to any investigation of predator–prey relationships. In this study, the functional response of female Scymnus syriacus Marseul (Col.: Coccinellidae) to different densities (10, 20, 40, 60, 80, 100) of third instar nymphs of Aphis gossypii Glover as prey was studied in an open patch experiment in a growth chamber (25 °C, 65 ± 5% RH and a photoperiod of 16L:8D h ). Using logistic regression, a type II functional response for female Scymnus syriacus was determined. The searching efficiency (a') and handling time (T_h) of the female predator using non linear least-square regression were estimated as 0.0769 ± 0.0136 h^? 1 and 0.3103 ± 0.0438 h., respectively. Mean times required for the female predator to settle in a patch were 10.20 ± 4.28, 6.58 ± 2.58, 12.58 ± 4.50, 4.53 ± 1.48, 5.14 ± 2.59, 3.87 ± 3.52 min at different prey densities, respectively. Maximum theoretical predation rate (T/T_h) estimated by Rogers' model for the female predator was 77.34. The proportion of female predators remaining in open patches at the end of the experiment was dependent on prey density (R² = 0.876). The type of functional response obtained here agrees with studies on this predator in closed patches.     

Differential expression of sex-related fat body proteins during the larval–pupal developmental stages of the silkworm (Bombyx mori)

The silkworm fat body is the site of many intermediary metabolic processes, and a source of sustenance for growth throughout the life cycle. Fat body proteins are responsible for storing nutrients, providing energy, and regulating hormones, and they have been identified using proteomic approaches. However, detailed differential expression of sex-related fat body proteins has not previously been evaluated. In the present study, we characterized the differential expression of sex-related fat body proteins, by using 2-dimensional gel electrophoresis (2-DE) followed by mass spectrometry identification and bioinformatics methods. We extracted the fat body proteins from 5-day-old fifth instar larvae (L5), 10-day-old fifth instar larvae (corresponding to the end of spinning [LE]), and 0-day-old pupae (P0) of the multivoltine silkworm variety “Da Zao”. We confirmed the presence of 11 important sex-specific expression proteins and 14 stage-specific expression proteins. We accurately identified 13 of these specific expression proteins, including actin, calponin-like protein, 75 kDa subunit NADH, receptor for activated protein kinase C from Bombyx mori (BmRACK), IMP (inosine monophosphate) cyclohydrolase, tropomyosin 1, β-tubulin, hypothetical protein, antichymotrypsin precursor, and 30 K protein precursor. We showed that BmRACK was differentially expressed between male and female silkworms. We discuss the biological roles of the specific expression proteins during the larval–pupal developmental stages.     

A whole genome screening and RNA interference identify a juvenile hormone esterase-like gene of the diamondback moth,Plutella xylostella

Juvenile hormone (JH) plays a crucial role in preventing precocious metamorphosis and stimulating reproduction. Thus, its hemolymph titer should be under a tight control. As a negative controller, juvenile hormone esterase (JHE) performs a rapid breakdown of residual JH in the hemolymph during last instar to induce a larval-to-pupal metamorphosis. A whole genome of the diamondback moth (DBM), Plutella xylostella, has been annotated and proposed 11 JHE candidates. Sequence analysis using conserved motifs commonly found in other JHEs proposed a putative JHE (Px004817). Px004817 (64.61 kDa, pI = 5.28) exhibited a characteristic JHE expression pattern by showing high peak at the early last instar, at which JHE enzyme activity was also at a maximal level. RNA interference of Px004817 reduced JHE activity and interrupted pupal development with a significant increase of larval period. This study identifies Px004817 as a JHE-like gene of P. xylostella.     

Key to the New Zealand species of Psyllaephagus Ashmead (Hymenoptera: Encyrtidae) with descriptions of three new species and a new record of the psyllid hyperparasitoid Coccidoctonus psyllae Riek (Hymenoptera: Encyrtidae)

Abstract  This paper records seven species of wasps in the genus Psyllaephagus (Hymenoptera: Encyrtidae) from New Zealand. All of these species are primary parasitoids of psylloids (Hemiptera: Psylloidea). Two are species previously described from New Zealand: P. acaciae Noyes and P. pilosus Noyes. Two are described Australian species which have established recently: P. bliteus Riek and P. gemitus Riek. Three new species are described here, from New Zealand: P. breviramus sp. nov., P. cornwallensis sp. nov. and P. richardhenryi sp. nov. All species are probably Australian in origin. A key to all seven Psyllaephagus species known from New Zealand is provided. An earlier first record of the Australian psyllid hyperparasitoid Coccidoctonus psyllae Riek (Hymenoptera: Encyrtidae), previously first recorded from New Zealand in 2006, is noted.