Release of two predators and two parasitoids to control aphids and whiteflies

The potential of the two predators,Chrysoperla carnea Steph. andCoccinella undecimpunctata Reich., as well as the two parasitoidsDiaeretiella rapae andEretmocerus mundus in an open field and under green house were conducted after several releases againstAphis gossypii, A. fabae, Brevicorine brassicae andBemisia tabaci. Double releases ofC. carnea (1∶5 predator∶aphids) achieved 100% reduction inA. gossypii after 12 days. A single release ofC. undecimpunctata (1∶50 predator∶aphids) resulted in 99.97% reduction in the same aphid. Releasing ofD. rapae to controlB. brassicae at the rate of 1∶50 resulted in 29% parasitism. ReleasingE. mundus for the control ofB. tabaci in cabbage at the rate of 5 adults/m² resulted in 32% parasitism. Three releases ofC. undecimpunctata adults in a greenhouse cultivated with soybean, decreasedA. fabae population from 207 to 7.6 aphids/plant.     

Paecilomyces tenuipes (Peck) Samson,ein seltener insektenpathogener Pilz an Noctuiden

The entomopathogenic fungusPaecilomyces tenuipes was isolated from dead noctuid pupae the identification of which was impossible. Some remarks are given on the morphology of this fungus rarely occurring in our regions. Besides the conspicuous synnemata and the oblong oval conidia (6,0–10,0×2,0–3,8 μm from culture, 4,5–7,5 ×2,0–2,5 μm from infected larvae) brown coloured and thick-walled appressoria were formed on glass surfaces. Pathogenicity tests showed thatP. tenuipes can infect as well larvae ofMamestra brassicae andAgrotis segetum as pupae ofM. brassicae andAutographa gamma. The formation of a perfect state was never observed.     

Antibiotic properties of the glucosinolates of Brassica oleracea var. acephala similarly affect generalist and specialist larvae of two lepidopteran pests

Glucosinolates may deter generalist insect feeding as their toxicity causes fitness damage, whereas insects specialized in brassicaceous plants may circumvent the toxic effect. By using no-choice leaf tests, we investigated whether larval development time, body weight, mortality and feeding rate of the generalist Mamestra brassicae (Lepidoptera, Noctuidae) and the specialist Pieris rapae (Lepidoptera, Pieridae), were affected by six genotypes of Brassica oleracea var. acephala, selected for having high or low concentration of sinigrin, glucoiberin (aliphatics) and glucobrassicin (indole). Two phenological plant stages were used. On young plants, M. brassicae most consumed the high sinigrin and low glucoiberin genotypes. Larvae weighed more on the high sinigrin plants. Development time took longer on the low glucoiberin genotype. On mature plants, consumption rate decreased on the high glucoiberin genotype. Larval weight decreased on the high sinigrin, glucoiberin and glucobrassicin genotypes, and development time increased with high glucobrassicin concentration. Pupal weight and mortality rate increased on mature plants, irrespective of the genotype. Pieris rapae fed most on young plants with high sinigrin, and larval weight increased on the high glucoiberin genotype. Mortality increased with low glucoiberin and low glucobrassicin. On mature plants, larval weight decreased with high sinigrin and glucoiberin. The high glucoiberin genotype was the less consumed and also induced a longer development time. High content of aliphatic glucosinolates offered mature plants significant antibiosis defence against both the lepidopterans, whereas the indole glucosinolate was marginally effective. Young plants were more consumed and increased larval weight likely because glucosinolate concentration was still not optimal.     

Über kombinierte Wirkungen eines Juvenoids (Altosid) und eines Bacillus-thuringiensis-Präparats (Bactimos) auf Larven der Stechmücken Culex pipiens molestus Forsk. und Theobaldia longiareolata Macq. (Dipt., Culicidae)

Exposing second and fourth instar larvae ofCulex pipiens molestus for 24 h to Altosid increased their tolerance to Bactimos. The interaction was apparent in fourth instar larvae treatment especially at the higher concentrations. Exposure bactimos to Altosid for 72 hours decreased its efficacy against the fourth instar larvae ofCulex pipiens molestus. The LT₅₀ values were significantly lower in larvae treated with Bactimos only than that treated with Altosid and Bactimos. Altosid briquets increased significantly the tolerance ofTheobaldia longiareolata larvae toBacillus thuringiensis var.israelensis at all concentrations tested. Generally, pretreatment mosquito larvae with Altosid followed by Bactimos, increased the tolerance of larvae to the bacterium, this may be due to the toxic effect of Altosid on the bacterium or to the changes in the physiological status of the treated larvae to tolerate the effect of bacterium. On the light of these studies, Altosid exhibited detrimental effect on the efficacy ofB. thuringiensis var.israelensis againstC. pipiens molestus andT. longiareolata larvae. Therefore, interactions between Altosid and Bactimos could not fit the integrated control of mosquitoes.     

Zur Morphologie und Entwicklung von Bracon instabilis Marsh. (Hym., Braconidae), eines Parasiten der Kartoffelmotte,Phthorimaea operculella Zell. (Lep., Gelechiidae) in Ägypten

Bracon instabilis Marshal is an ectoparasite attacking the larvae ofP. operculella in Egypt. According to available literatures, this is the first study onB. instabilis. The laboratory rearing of this parasite was undertaken on the third and fourth larval instars ofP. operculella and the method was mentioned in details. Certain aspects of the morphology of the immature and adult stages were given. The durations of the immature stages of the parasite were estimated at 15 and 25°C and 60±5% R.H. The total durations of the immature stages (from egg to adult) were 39.62 and 11.19 days at 15 and 25°C, respectively.     

Über Eignung und Reaktion überwinternder und aktiver Raupen von Sesamia cretica Led. (Lepid., Noctuidae) in bezug auf den Parasitoiden Bracon brevicornis Wesm. (Hymen., Braconidae)

Laboratory studies were undertaken to determine the differential response and suitability of 2 types of host larvae ofSesamia cretica (hibernating and active) to the development of the braconid,B. brevicornis. The parasitoid was able to immobilize the 2 forms of larvae. However, hibernating larvae were significantly less sensitive to the parasitoid's venom than active larvae. Parasitoid parents (specially females) which associated with hibernating larvae were significantly longer-lived than those kept with active larvae. Life cycle period of the parasitoid did not affect with any of the 2 types of larvae. However, numbers of each of cocoons and emerged adults/larva were significantly higher in case of hibernating than in case of active larvae. Moreover, the produced adults from hibernating larvae were significantly larger in their size. Therefore the hibernating host larvae will serve better for mass colonization of this braconid.     

Untersuchungen zur Kältetoleranz und Überwinterung der Deutschen SchabeBlattella germanica (L.) (Blattodea,Blattidae) unter Freilandbedingungen

The extremly biotic and abiotic conditions of a decompositiontip supported the mass population ofB. germanica which enabled the development of a new race by means of evolution factors. In experiments under laboratorical and outdoor conditions the cold-tolerance of this new race was studied. Considering the fact, thatB. germanica can subsist a middle-European winter under outdoor conditions, we may conclude, that the spreading of this animal will not soon come to an end.     

Beziehungen zwischen Fruchtwechselfolgen einerseits und dem Auftreten der Tomaten-Umfallkrankheit und der Zwiebelwelke sowie den Populationen ihrer Pathogene und des Antagonisten Bacillus subtilis im Boden andererseits

Crop rotation showed a pronounced effect on incidence of tomato damping-off and onion (Fusarium) basal rot as well as on the soil population of the two disease incitants. Out of nine rotation systems, wheat/sorghum and wheat/maize preceding tomato diminished damping-off while clover/maize, lentil/sorghum, wheat/sorghum and wheat/maize preceding tomato diminished damping-off while clover/maize, lentil/sorghum, wheat/sorghum and wheat/maize preceding onions increased basal rot incidence. First crops of the rotation system as well as the second crop were of noticeable effect onRhizoctonia solani andFusarium oxysporum f. sp.cepae as onBacillus subtilis (antagonistic to both fungi) population in soil. Almost all rotations increased population ofF. oxysporum f. sp.cepae andB. subtilis in soil while response ofR. solani was variable. The results show thatBac. subtilis did not correlate with tomato damping-off or onion basal rot. There must be some other factors found in the soil that play a role in effect of crop rotation on disease incidence.     

Zur Biologie und biologischen Bekämpfung des Tabakkäfers,Epithrix hirtipennis Melsh. (Col., Chrysomelidae)in Italien

Epithrix hirtipennis Melsh. is a relatively new insect pest in South Europe on tobacco. Observations reported here on its biology and behaviour differ in some pattern from those in the North American population. For the control of TFB (Tabac Flea Beetle) big amount of chemical insecticides are used, consequently there is a requirement for alternative methods. Experiments were carried out withB. thuringiensis ssp. kurstaki and ssp.tenebrionis, Beauveria bassiana, Steinernema carpocapsae andHeterorhabditis sp. in laboratory, semifield and field conditions. The results show that in summertime against the adults by help ofBac. thur. tenebrionis in principle a successful biological control ofE. hirtipennis seems to be possible.     

Impact of glucosinolate in relation to leafminer,Liriomyza brassicae Riley (Diptera: Agromyzidae) infestation in crucifers

Eight species belonging to the Family Cruciferae were classified to lafminer resistant, tolerant and susceptible on the basis of leafminer infestation. They were analyzed for the glucosinolate content and correlated with leafminer infestation. Total glucosinolate content in general and sinigrin content in particular appeared to have the ability to repel the attack ofLiriomyza brassicae, while gluconapin appeared to attract them. The percentage of infestation, the number of mines and the number of living larvae were estimated for evaluating the glucosinolate efficacy againstL. brassicae on cabbage.     

Über die natürlichen Krankheiten der Frostspanner Operophthera brumata L. und Erannis defoliaria Clerck (Lep., Geometridae) im Spessart,Bayern

Studies of the host-parasite relationships in populations of larvae of the family Geometridae collected from forest stands in the Spessart-mountains (Bavaria, Germany) were conducted in 1977. Four species of Microsporidia and one Nuclear-Polyhedrosis-Virus were recovered from larvae ofOperophthera brumata L. undErannis defoliaria Clerck. Three of the species of Microsporidia were identified asPleistophora schubergi Zwölfer 1927 (infecting intenstinal-carity).Pleistophora c. f.schubergi (infecting fat-body) andTelochania cheimatobiae Krieg 1956, while the fourth species of Nosematidae, differed from all species of Microsporidia at Geometridae previously described. The nameNosema operophthera sp. n. has been proposed for this pathogen. Data on the levels of infection of the natural populations of the pests are given in table 2. A downward trend in annual levels of the infection was noted. Of the larvae ofO. brumata collected in 1977 54% were infected, namely 30% byTelochania cheimatobiae 23% bothPleistophora and 2.5% by the mixt-infection ofNosema operophthera sp. n. andP. schubergi; while ofE. defoliaria 44% were infected, namely 30% by Nuclear-Polyhedrosis Virus and 6% byPl. schubergi. An ultrastructural study of the infection of cells ofErannis defoliaria by the Nuclear-Polyhedrosis Virus is presented. The virus develops in tracheal-matrix, hypoderm and fat-body cells. It meets all the criteria for incorporation into the Family Baculoviridae.     

Übertragung zweler bakterieller Pathogene in den Körper von Sesamia cretica Led. (Lep., Tortricidae) mittels des Legebohrers von Bracon brevicornis Wesm. (Hym., Braconidae)

Laboratory trials were undertaken to investigate the transmission of 2 bacterial pathogens (Serratia marcescens Bizio andBacillus thuringiensis Berliner) by the ovipositor of a braconid parasitoid,Bracon brevicornis Wesmael into the body cavity ofSesamia cretica Lederer. The braconid's ovipositor was able to transmit the 2 bacterial pathogens and plays as inoculating needle. The host larvaeS. cretica were significantly immobilized faster by the contaminated ovipositor of a parasitoid (in case of the 2 pathogens). After successful transmission of the bacterial pathogen into the body cavity of host larvae, different deleterious effects were significantly found for the parasitoid and its progeny specially in case ofS. marcescens. Through contamination of the ovipositor, the non-sporeforming bacterium,S. marcescens has more pathogenic effects on the parasitoid and its progeny than the sporeforming bacterium,B. thuringiensis.     

Wirkungen von Temperatur und Luftfeuchtigkeit auf die Embryonalentwicklung und das Eischlüpfen bei der SchildzeckeHyalomma marginatum Koch (Acari,Ixodidae)

Effect of temperature and relative humidity on embryonic development and egg hatch ofHyalomma marginatum Koch (Acari, Ixodidae) Effect of different temperatures (25, 30, 35, 40°C) and relative humidity (RH) levels (50, 75, 90%) on embryonic development and hatching ofHyalomma marginatum was investigated. The percentage of dead eggs and embryos, percentage of morphologically normal larvae, percentage of abnormally hatched larvae and percentage of larvae with morphological malformations were determined for each condition. Embryonic development and egg hatch proceeded at 25–35°C in all relative humidity levels tested. However 50% RH was unfavourable for these processes. The optimal conditions for larval development were found to be: temperature of 25–30°C and relative humidity of 75%. Under these conditions 72.7–87.8% of examined egg hatched into normal larvae.     

Bekämpfung von Insekten im Pflanzenschutz mitBacillus thuringiensis-Präparaten und deren Einfluß auf die Umwelt. 2. Mitteilung

During the application ofBacillus thuringiensis for control of pest insects in forestry and agriculture not only wood or target crops are treated with viable spores, but also the air and soil will be contaminated. The fate of these spores is especially relevant with regard to residues and protection of drinking water supply. Concerning the ecology ofB. thuringiensis experimental results are discussed in connection with informations on the natural level of bacterial contaminations of plants, air, soil and water. On this base, however, no arguments could be obtained concerning a risk assessment on human health or environmental pollution in connection with application of commercial preparations ofB. thuringiensis at recommended doses, even not in water catchment areas.     

Der MaiskäferSitophilus zeamais Motschulsky (Col., Curculionidae) und seine Begleitfauna — eine Freilandstudie auf den Philippinen

During the years 1982 to 1984 the attack ofSitophilus zeamais has been studied on corn fields owned by small-scale farmers in Cebu (Central Philippines). The invasion bySitophilus started 4 to 5 weeks before harvest and increased continously up to harvest time, when 93% of the drafted cobs could be occupied. A long lasting and for this region unusual drought (8 months) caused a drastic collapse of the population during the following planting season. But another planting season later the field population has been recovered and showed a high rate of infestation again. The frass-holes caused byHeliothis armigera, and said to be important as an “entry” forSitophilus, have been significant only during the beginning of the attack byS. zeamais, while the husk was still tight. During the corn ripening and the desiccation of the huskSitophilus has best chances to get into the cob without influence from outside. This stage coincides with the increase of the population density. The control ofH. armigera is not considered to be effective to keep the infestation ofSitophilus on a minimum level. A distinct orientation behaviour byS. zeamais regarding the main wind direction has been noticed in the field. BesideSitophilus the Nitidulid beetlesCarpophilus mutilatus and (but less important)C. humeralis have been found abundantly within the cobs. The drought did not show any obvious influence on the population ofC. mutilatus. Some further observations on the field infestation byS. zeamais are described.     

A biochemical approach to potentiate the activity ofBacillus thuringiensis against corn borers

Due to the fact that the persistence ofBacillus thuringiensis (B.t.) is very short in the field as affected by exposure to ultraviolet radiation, some biochemical approaches have been adopted in an attempt to increase potentiation of the pathogen against the two lepidopterous corn borers,Chilo agamemnon andOstrinia nubilalis. These approaches were based on the incorporation of some selected non-toxic chemical compounds with different modes of action with the endotoxin ofB.t. fed to the larvae and thus resulting in its potentiation. Among the compounds tested, some representatives of inorganic salts, organic acids, protein and lipid solubilizing agents, amino acids and amides showed an obvious potentiation to the endotoxin activity against the target insects. Inorganic salts, such as, calcium oxide, calcium carbonate, zinc sulphate and potassium carbonate at 0.1% potentiated the activity of the product Dipel 2X (B.t. var.kurstaki) against the two tested species in varying degrees. With regard to protein solubilzing agents, urea, sodium thioglycollate and EDTA enhanced the potency ofB.t. againstO. nubilalis with a fold increase of 1.4–2.3. The lipid emulsifying agent Tween 80 (0.5%), caused 1.3 fold increase in the potency ofB.t. With respect toC. agamemnon, sodium thioglycollate and EDTA (0.1%) were effective in potentiating the activity ofB.t. with fold increase of 3.1 and 1.2, respectively, while urea caused a decrease in the potency ofB.t as compared with the control. The lipid emulsifying agent Tween 80 (0.5%) caused 1.3 fold increase in the potency ofB.t. The potentiating effect of aromatic compounds is not obvious with respect to the tested insect species. With amino acids and amides, it appears that some of the tested compounds enhanced the potency ofB.t. against the tested insect species but in varying degrees. The mode of action of the tested compounds has been discussed in the light of the results obtained.     

Zur Wirkung von Nemacur- und Temik-Granulaten auf Wurzelgallen-Nematoden (Meloidogyne spp.) bei der Tomate

The susceptibility of the two single populations of root-knot nematodes invading tomato roots,Meloidogyne javanica andM. incognita acrita, in comparison with a mixed population of the two species was investigated to the granular nematicides, Nemacur and Temik. Root-gall indices ofM. incognita acrita were reduced more than ofM. javanica. In addition, root-gall indices of the mixed population and a single population,M. incognita acrita, were the same.     

Trichogramma evanescens West. (Hym., Trichogrammatidae) as an egg parasitoid of Grape MothLobesia botrana (Den. & Schiff.) (Lep., Tortricidae)

The adaptation of the primary internal parasitoid,Trichogramma evanescens (Westw.), as an egg parasitoid ofLobesia botrana (Den. & Schiff.) was the first report in Alexandria region, Egypt. The life-span of this parasitoid on eggs ofL. botrana andSitotroga cerealella Ol. was investigated. The duration from egg to adult, longevity of adult stage, sex-ratio and total life cycle each of the two hosts were recorded. The ovipositional periods of mated females ofT. evanescens on egg ofL. botrana at 27±2c^o and 75±2% R.H. were studied. Also, percentages of parasitism byT. evanescens ranged from 22%–64% on the eggs ofL. botrana. Therefore, this parasitoid was very efficient as a biocontrol agent against the most serious grape pestL. botrana in Egypt.     

Effect of larval selection with two bioinsecticides on susceptibility levels and reproductive capacity ofAedes aegypti (L.)

Two bacterial insecticides,Bacillus thuringiensis H-14 andB. sphaericus 1593 were evaluated for larvicidal potency against mosquito larvae ofAedes aegypti. LC₅₀ values showed thatB.thuringiensis H-14 (4×10⁵ spores/ml) had a higher pathogenicity against fourth larval instars ofA. aegypti thanB. sphaericus (3.1×10⁶ spores/ml) by about 7.75 times. Larval selection with LC₉₀ of both pathogens for 8 successive generations caused a decrease in the susceptibility levels of selected strains ofA. aegypti as compared with the original strain. Moreover, the results indicated that the effect of larval selection with the above bioinsecticides led to an obvious reduction in the egg production and hatchability of eggs produced by mosquito adults that developed from surviving larvae.     

Potential of Ethiopian mustard, <Emphasis Type="Italic">Brassica carinata</Emphasis> as a trap crop for large white butterfly, <Emphasis Type="Italic">Pieris brassicae</Emphasis> infesting Indian mustard, <Emphasis Type="Italic">Brassica juncea</Emphasis>

The large white butterfly, Pieris brassicae (L.), is an important pest of Indian mustard, Brassica juncea (L.) Czern., and inflicts heavy damage to all the above ground plant parts with strong yield reducing impacts. Farmers have few practical options other than to spray insecticides to protect their crop. In this study, an attempt was made during 2012–2013 and 2013–2014 crop seasons at Ludhiana, India, to evaluate Ethiopian mustard, Brassica carinata A. Braun as a trap crop to manage this pest as an alternate pest management strategy. B. carinata borders surrounding B. juncea were compared to chemically protected B. juncea and control (without B. carinata borders) plots for their effects on P. brassicae infestation and grain yield. Oviposition preference of adult butterflies was studied in a two-choice test in field cages, while the effect of two host plants on larval performance was studied under laboratory conditions under no choice conditions. B. juncea plots bordered with B. carinata harbored significantly lower larval population compared to control B. juncea plots during both the seasons. The grain yield in the bordered plots was also significantly higher than that from control plots and was statistically non-significant from that obtained in chemically protected plots. Female butterflies showed distinct oviposition preference for B. carinata over B. juncea and the larvae reared on B. carinata completed development in shorter period and grew bigger and heavier than those reared on B. juncea. Results indicated that B. carinata has potential to be used as trap crop to manage P. brassicae.