Souad A L Shairra

A study to evaluate the pathogenicity of entomopathogenic nematodes and fungi against the peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae) was carried out under laboratory conditions. The nematodes species tested were; Heterorhabditis bacteriophora; Steinernema carpocapsae and S. riobrave. The fungi were; Metarhizium anisopliae and Beauveria bassiana. Different concentrations were used against immature stages of B. zonata, by contact and/or soil inoculation techniques. Results showed that both Steinernema species were more effective on full-grown larvae than H. bacteriophora in contact treatment, whereas H. bacteriophora was more effective in soil, as it induced higher mortality of B. zonata pupae at both techniques. Mortality rates of B. zonata pupae increased significantly by increasing the concentration of the two tested fungi at the same time of exposure. Adult mortality was affected by soil treatments as B. bassiana treatments significantly increased mortality rates compared to M. anisopliae and control treatments. Emerged adults from treated pupae with both fungi showed mycosis on the outer surface, additionally some emerged adults showed malformation and mostly failed to emerge. Results suggested that entomopathogenic nematodes and fungi can be used as alternative tools of pesticides for controlling B. zonata after validating protocols of field conditions.

Use of contact bioassays of certain bio-products, as aspirin (eicosanoid inhibitor), lactose (lectin inhibitor) and garlic oil, solely or in combination with the fungus, Metarhizium anisopliae showed efficacy against 5 th nymphal instar of Schistocerca gregaria (Forskal). Direct effects on some biological and physiological parameters of the pest were recorded. Moreover, combination treatments showed higher virulence assay than the single ones. Blood cells (plasmatocytes and granulocytes) were swallowed by rupture in plasma membrane. At the same time, granulocytes showed shrinkage with distortion in the cell membrane and undistinguished nucleus when compared with control cells. Pathological changes in the plasmatocytes and granulocytes indicated that the use o f fungus and bio-products might act as immune-suppressants. These findings might be taken into consideration in evaluating the success of microbial insecticides and certain bioproducts against S. gregaria as they open new possibilities to develop highly efficient combined bioproducts on the basis of the effects of the entomopathogenic fungi and the inhibitors.

ABSTRACT

Pathogenicity of the two entomopathogenic nematodes (Heterorhabditis bacteriophora Poinar (HP88 strain) and Steinernema riobrave) and the two fungi (Metarhizium anisopliae and Beauveria bassiana) and their combinations were studied against the 3rd instar larvae of the cotton leaf worm Spodoptera littralis (Boisd.). LC50 values of H. bacteriophora were the most potent after 96 and 120 h of treatment, reached 568.6 IJs/ ml and 313.6 IJs/ ml, with a toxicity index (Ti=100& 100), respectively. Meanwhile, at 96 and 120 h post inoculation, LC50 values of S. riobrave were 701.9 IJs/ ml and 353.1 IJs/ ml with a toxicity index (Ti=56.74 and 88.81), respectively. Seven days post treatment, LC50 of M. anisopliae reached 2.897 E×108 conidia ml-1, with a toxicity index (Ti = 100). On the other hand, B. bassiana LC50 value was 7.839 E×1011 spores ml-1 with a toxicity index (Ti = 36.96). Based on the co-toxicity factors; H. bacteriophora in combination with B. bassiana exerted an additional action with a co-toxicity factor (9.5). Also, the combination of S. riobrave with M. anisopliae gave an additional action based on a co-toxicity factor (-2.2), at 96h post treatment. Results indicated that the tested two bio-agents had variable mode of actions and resulted to insignificantly effects with additive actions. Observed mortality caused by both tested bio-agents was higher as compared to the use of each agent singly.

Keywords: Spodoptera littoralis; Entomopathogenic Nematodes; Entomopathogenic Fungi, Control, Integration.

Snails and slugs are considered a serious pest attacking several economic crops so it was important to search for convenient solve for this problem. Fungal entomopathogens, Metarhizium anisopliae var acridum on garden snails showed low mortality percentages of adult garden snails at 21 days after treatments which recorded, 0%, 2%, 2% & 3% for doses 103,104, 105 &106 spores / snail, respectively. On the 14th and 21st days there were no differences in mortality percentages. Also, three local oils, a liquid soap and a mixture of miscible oil and soap were tested under laboratory conditions against the garden snails Helix aspersa. Results showed that all the treatments gave 99.9 % mortality on pre adult stage. In case of adult stage mortality % varied where chemi oil (mayonnaise), KZ oil, Chemi oil (miscible) and misrol soap recorded 60, 0, 83.3 and 100% mortality, respectively. The LC50 of both chemi oil and misrol soap were 1.515 and 1.647, respectively. When chemi oil (miscible) mixed with misrol soap the mortality % decreased to reach 16.67% on adult stage which may indicate that the usage of the mixtures is useless against garden snails.
Keywords: mineral oils; liquid soap; Control; Helix aspersa; Garden snails.

The entomopathogenic nematodes, Steinernema scopterisci and liquid Misrol soap (410) were used alone or mixed together to control the brown garden snails, Cor¬nu aspersum (formerly Helix aspersa). Percent mortality of garden snails reached 49.9%, 100%, 100% and 66.6% in pre-adult at nematode doses 50,100,150 and 200 of infective juvenile (IJs)/ml distilled water and LD50 was 4.1083 IJs/ml at 72h post infection respectively. However, after spraying alone on garden snails, percent mortality reached 100% in pre-adult and 80% at adult snails. Mixtures of Misrol liquid soap 1.5% and the same nematode dosage used together against the garden snails for 72h. the results showed increase in mortality percent of adult snails reached to 16.6 % & 100% at  of doses (150 & 200 IJs/ml) respectively and the LD50 values were 73.447 IJs/ml for pre-adult &161.4364 IJs/ml for adult. Results, also, indicate that the immature stages of garden snails were greatly sensitive than adult stages. Therefore, nematodes suspension when used alone or mixture with Misrol liquid soap (410) at 1.5% can control garden snails. Also, this material saves great amount of pesticides, cost and minimizes the environmental pollution. 
Keywords: Entomopathogenic nematodes; Liquid soap; Control; Garden snails.

ABSTRACT

The entomopathogenic nematodes, Heterorhabditis and Steinernema together with their associated bacteria Photorhabdus and Xenorhabdus, respectively have come about because of their biological control potentials. To address the immunocompetence of the host insect Schistocerca gregaria following nematode infection, we tested a hypothesis that the insect immune-mediating eicosanoid pathway may be affected by the virulent action of the Egyptian nematode isolate H. indica(RM1). Haemocoelic injection of the nematode into the fifth instar nymphs of Sc. gregaria evoked the haemocyte microaggregation and nodulation reactions as well as increased the mortality percentages of these economically important pest. Separate treatments with specific inhibitors of the phospholipase A2; the cyclooxygenase and the dual cyclooxygenase /  lipoxygenase pathways, reduced both haemocyte microaggregation and nodulation reactions, supporting the point of view that nodule formation is a complex process involving both cyclooxygenase and lipoxygenase products. The inhibitory effects of the phospholipase A2 inhibitor, dexamethasone, on microaggregation and nodulation were obviously apparent during the first hour of injection and these effects increased greatly over the following 24h . The dexamethasone effects were expressed in a dose-dependent manner and they were reversed by the co-injection of the nematode-injected insects with the exogenous eicosanoid-precursor polyunsaturated fatty acid, arachidonic acid (C20:4n-6). These findings strongly support the identification of microaggregation and nodulation as a specific insect cellular defense reactions that are mediated by eicosanoids. The Sc. gregaria nymphs contain trace levels of the eicosanoid-precursor polyunsaturated fatty acids in six different tissues as detected by mass spectrometry.
Keywords:Entomopathogenic nematodes; microaggregation; nodulation; inhibitors; eicosanoid; Schistocerca gregaria.

ABSTRACT
The nematode isolates tested were collected from different localities of Egypt. Some experiments evaluated the infectivity and susceptibility of Heterorhabditis bacteriophora and H.indica as biocontrol candidates against some economics agricultural insect pests, such as Spodoptera littoralis, Agrotis ipsilon, Sesamia cretica, Phthorimaea operculella and Spodoptera exigua,. The two tested nematode species grew faster in S.littoralis and Ph.operculella larvae than in the other host larvae. The survival of H.bacteriophora and H.indica in distilled water was affected by the two combined factors, exposure time and temperatures. All individuals of H.bacteriophora and H. indica were viable after exposure for 48 hours to temperatures ranged from 5-30C . At lower (0C and -5C) and higher temperatures (35 and 40C), the survival decreased but this reduction was more prominent at higher temperatures. Effect of temperature and duration of the exposure time on the infectivity of the nematode H.indica (EASD77 isolate) and H. bacteriophora (EASD98 isolate) were proved highly virulent against the Egyptian cotton leaf worm, Spodoptera littoralis. The highest mortality percentages were recorded at the highest two temperature tested 30 and 35C. In contrast, there was no mortality recorded at the cooler degree of temperature test (10C). The changes in total haemocyte counts (THCs) and differential haemocyte counts (DHCs) of S. littoralis larvae against H. indica nematode (EASD77 isolate)  are important criteria determining cellular immune reactions.
Key words : nematodes, biological control, temperature, cellular immune .
* Biological control Department, plant protection Institute.
** Department of Entomology, Faculty of Science, Cairo University.
*** Department of Zoology and Nematology, Faculty of Agriculture, Cairo University.

Abstract
Pathogenicity  of two entomopathogenic  nematodes, Heterorhabditis bacteriophora Poinar (HP88 strain) and Steinernema riobrave  and two fungi, Metarhizium  anisopliae and  Beauveria bassiana as will as the effect of their combinations against 3rd instar larvae of cotton leaf worm, Spodoptera littoralis (Boisd.).  Data revealed that, the tested nematodes differed in their efficacy against 3rd instar larvae of S. littoralis. The LD50 values for S. riobrave  reached 438.8 & 180.1/ IJs ml/100g diet indicated the most potent nematodes at 48 & 72 h post treatment, respectively. On the contrary, LC50 reached 584.5 &199.2/ IJs ml/100 g diet, for H. bacteriophora, respectively.  The LC50 values for fungus, B. bassiana revealed least mortality percentage (LC50= 7.84 x 1011spores ml-1) and M. anisopolie was the most potent fungus (LC50 = 2.89x 108spores ml-1) after 7 days of treatment. The probit regression lines for combination of the tested concentration of fungi and nematodes (B. bassiana+HP88) and (M. ansoplae + S. riobrave) against 3rd instar of S. littoralis, showed highest larval mortality that increased with increased fungi spores and/ or nematodes juvenile's concentrations.
Keywords: Spodoptera littoralis;  Heterorhabditis bacteriophora  (HP88 strain) ; Steinernema riobrave;  Metarhizium  anisopliae; Beauveria bassiana.

Abstract True spiders represent one of the most important natural predatory species in Egyptian
fields. In this work, common true spiders were surveyed in wheat, cotton and maize fields, and were
counted weekly by using the direct method. For evaluating the feeding consumption of true spiders,
five feeding cases were tested (as preys). These cases were: eggs of Ephestia kuehniella, eggs of
Phthorimaea operculella, one day eggs and larvae of E. kuehniella, larvae of E. kuehniella and P.
operculella and larvae of E. kuehniella only. Results obtained revealed that, the highest average daily
consumption for each spider was recorded in case of feeding on eggs of P. operculella. While, the
longest survival period was recorded in case of feeding on larvae of E. kuehniella.
ª 2012 The Egyptian German Society for Zoology. Production and hosting by Elsevier B.V. All rights
reserved.

Abstract
            The present work mainly focused on the susceptibility of Schistocerca gregaria (Forskal( 5th instar nymphs to the entomopathogenic nematodes, Steinernema glaseri (Rhabditida: Steinernematidae)  as a natural exposure experiment. The entomopathogenic nematode, S. glaseri turned out to be successful parasitoid of the orthopteran insect S.  gregaria. The death rate of locusts (sprayed with nematode on clover leafs) was remarkably high. Nematode killed approximately 65% of the locust with in72 hours post infection at semi-field trial. The impact of parasitation on locusts' immune defense was closely investigated for S. gregaria parasitized by S. glaseri.  Nymphs died within 48-72 h after being fed clover leafs contaminated with 1500/ml S. glaseri juveniles or previously contaminated with the dual cyclooxygenase/lipoxygenase inhibitor, phenidone. The injection of S. gregaria nymphs with, phenidone exhibited significant reduction in microaggegation in response to the nematode injections. At 12 h post-injection, insignificant differences were recorded of the individual inhibitor on microaggregation, compared to the ethanol-treated (control) nymphs. Cellular defense components were strongly influenced by parasitation within the first 12 h after injection of the nematodes.  Nymph's haemolymph was assayed.

Abstract
    The 5th nymphal instar of S. gregaria was treated with different doses of Heterorhabditis bacteriophora Hp88 or Allium sativum (garlic) extract, as well as a combination of both of them. The insecticidal activity of Hp88 and garlic extract showed a significant increase in the mortality by increasing the concentration and the post infection time. The study was designed to follow up the defense reaction of the treated nymphs' haemocytes. The role of garlic oil on treated nymphs was studied on the detoxification and the digestive enzymes. Where the activity of the lactatedehydrogenase (LDH) and the α-esterase increased significantly by increasing the post infection time. On the other hand, the activity of β - esterase increased significantly only after 3 hours post infection, but decreased significantly by increasing the post infection time. Whereas the activity of the digestive enzymes decreased and the amylase activity decreased significantly. The obtained results revealed that the studied biocontrol agents can be recommended for controlling S. gregaria. 
Kay words: locust, garlic oil, nematode, detoxification enzymes, digestive enzymes, immunity, haemocytes.

ABSTRACT

Infection with the entomopathogenic nematode, Steinernema glaseri caused death to the Egyptian cotton leafworm, Spodoptera littoralis larvae. Mortality of insect larvae increased when the nematodes were exposed to eicosanoid biosynthesis inhibitor dexamethasone. These effects were reversed when dexamethasone was used together with the eicosanoid precursor, arachidonic acid (AA), and other eicosanoid biosynthesis inhibitors (e.g. phenidone, ibuprofen, and indomethacin). In vivo infection with S. glaseri infective juveniles has enhanced nodule formation. Nodule numbers were reduced by dexamethasone, and restored by AA. In an in vitro experiment, incubation of the insect hemolymph with the nematode symbiotic bacteria, Xenorahbdus  nematophilus has raised numbers of  both plasmtocytes and granulocytes in insect hemolymph and this was inhibited by dexamethasone, suggesting that dexamethasone acts directly on hemocytes formation. Although this inhibition was only partially reversed by arachidonic acid, we suggest that the S. littoralis immune response to insect pathogenic nematodes is normally modulated by physiological systems that include eicosanoid biosynthesis. These observations indicate  that virulence of entomopathogenic nematode can be improved by compromising the insect host’s immune system.

Keywords: Arachidonic acid, Eicosanoids; insect hemocytes; insect immune system; Nodule formation; Steinernema glaseri; Spodoptera littoralis, Xenorhabdus nematophilus.