Predaceous Insects Research Articles

Description of the immature of Podisus graziae Brugnera, Roell & Lemaître, 2021 (Heteroptera: Pentatomidae: Asopinae)

As predaceous insects, the Asopinae have a great economic importance. The knowledge about the development of the species is essential for use in biological control programs. However, only 1% of the Neotropical Asopinae species have the immature stages known. In this work we describe the egg and the five nymphal stages of Podisus graziae Brugnera, Roell & Lemaître, 2021 using light and scanning electron microscopy. The results show that P. graziae eggs and nymphs present unique characters which are not observed in other species of the genus and subfamily. As other Podisus species, the egg present long aero-mycropilar processes, however, the chorion and operculum have a ring of minute spine-like projections. As main diagnostic characters of nymphs, the iridescent coloration of head, thorax and abdominal plates, and a pair of yellow spots in the pronotum and anterior region of abdomen are noticed.

Sublethal effects of an indoxacarb enantiomer insecticide on Plutella xylostella caterpillar and Chrysoperla sinica predator

Plutella xylostella (L.) is a migratory species and an important insect pest of cruciferous crops worldwide, and Chrysoperla sinica (Tjeder) is a predaceous insect of agricultural and forest pests in the field. Indoxacarb has two enantiomers: (+)-S-indoxacarb and (−)-R-indoxacarb. This study was conducted to clarify the selective toxicity and sublethal effects of both enantiomers on P. xylostella and C. sinica. The (+)-S-indoxacarb isomer had greater acute toxicity to P. xylostella and C. sinica, while (−)-R-indoxacarb had less toxicity to P. xylostella and low toxicity to C. sinica. Lethal concentration 25 % (LC25) of (+)-S-indoxacarb had significant effects on the development, population, and fecundity of P. xylostella and C. sinica. The LC25 concentration of (−)-R-indoxacarb had a significant effect on the oviposition of P. xylostella. The field recommended concentration of (−)-R-indoxacarb significantly affected the pupal stage, adult survival rate, oviposition, and larval survival rate of C. sinica. Both enantiomers could significantly affect the search efficiency, successful attack rate, prey handling time, and maximum predation of C. sinica larvae, and the effects of (+)-S-indoxacarb alone were greater than those of (−)-R-indoxacarb. This study provided evidence of the different selective toxicity, sublethal effects of indoxacarb enantiomers on P. xylostella and C. sinica, which of the results could provide a basis for more rational use of indoxacarb in ecosystems.

Beyond the fish-Daphnia paradigm: testing the potential for pygmy backswimmers (Neoplea striola) to cause trophic cascades in subtropical ponds.

Trophic cascades, or indirect effects of predators on non-adjacent lower trophic levels, are a classic phenomenon in ecology, and are thought to be strongest in aquatic ecosystems. Most research on freshwater trophic cascades focused on temperate lakes, where fish are present and where Daphnia frequently dominate the zooplankton community. These studies identified that Daphnia often play a key role in facilitating trophic cascades by linking fish to algae with strong food web interactions. However, Daphnia are rare or absent in most tropical and subtropical lowland freshwaters, and fish are absent from small and temporary water bodies, where invertebrates fill the role of top predator. While invertebrate predators are ubiquitous in freshwater systems, most have received little attention in food web research. Therefore, we aimed to test whether trophic cascades are possible in small warmwater ponds where Daphnia are absent and small invertebrates are the top predators. We collected naturally occurring plankton communities from small fishless water bodies in central Texas and propagated them in replicate pond mesocosms. We removed zooplankton from some mesocosms, left the plankton community intact in others, and added one of two densities of the predaceous insect Neoplea striola to others. Following an incubation period, we then compared biomasses of plankton groups to assess food web effects between the trophic levels, including whether Neoplea caused a trophic cascade by reducing zooplankton. The zooplankton community became dominated by copepods which prefer large phytoplankton and exhibit a fast escape response. Perhaps due to these qualities of the copepods and perhaps due to other reasons such as high turbidity impairing predation, no evidence for food web effects were found other than somewhat weak evidence for zooplankton reducing large phytoplankton. More research is needed to understand the behavior and ecology of Neoplea, but trophic cascades may generally be weak or absent in fishless low latitude lowland water bodies where Daphnia are rare.

Sublethal effects of tolfenpyrad on the development, reproduction, and predatory ability of Chrysoperla sinica

The lacewing, Chrysoperla sinica, is a predaceous insect that is important in crop pest management. Chemical pesticides have adversely impacted predaceous insect species. Here we studied the effect of tolfenpyrad on C. sinica. The acute toxicity of tolfenpyrad to the second-instar larvae was determined and indicated that tolfenpyrad is a medium-risk insecticide. Sublethal concentrations (LC10, LC20, and LC30) of tolfenpyrad had effects on the development, reproduction, and predatory ability of C. sinica. When the second-instar larvae of C. sinica were exposed to sublethal concentrations of tolfenpyrad, the activities of protective enzymes, such as superoxide dismutase, peroxidase, and catalase, and detoxification enzymes, including carboxylesterase, glutathione-S-transferase, and P450 monooxygenases, were increased with exposure time. The second-instar larvae of C. sinica exposed to sublethal concentrations of tolfenpyrad exhibited an oxidative stress response that increased the levels of malondialdehyde and reactive oxygen species (ROS). Within 48–120 h after treatment, the contents of mitochondrial respiratory chain complex I and adenosine triphosphate in the second-instar larvae were decreased. This resulted in an imbalance between the production and clearance of ROS and caused cellular damage.

Notes on the Citrus Rust Mite, Phyllocoptruta oleivora (Ashmead), as a Major Pest of Citrus in Indonesia

Most citrus farmers in Indonesia believed that rust on citrus fruits resulted from insect attacks. This research aims to determine the cause of rust on citrus fruit and its damage intensity. The study was carried out in commercial citrus plantations in three provinces, on Citrus sinensis and C. reticulata plantations in East Java, C. reticulata and C. suhuensis in West Kalimantan and C. suhuensis in North Sumatra. An additional observation was also conducted to collect mite specimens on citrus plantations in Malang, East Java. Scanning Electron Microscope (SEM) and light microscope were used to observe and identify each collected sample. Results showed that the cause of rust-colored citrus fruit in three provinces is the citrus rust mite, Phyllocoptruta oleivora (Ashmead). It belongs to the family Eriophyidae with two pairs of legs with regular segmentation, five-rayed featherclaws, and a net pattern on prodorsum. The specific damage produced by this mite is rust-colored symptoms. Damage intensity of citrus rust mite in tree provinces averaging 32.6%, ranging from 30 to 40%, and ca. the mite attacks 90% of citrus fruits. Predaceous mites, predaceous insects, and entomo-acaropathogenic fungi are found on plantations.

Identification and characterization of microRNAs in the immature stage of the beneficial predatory bug Arma chinensis Fallou (Hemiptera: Pentatomidae).

MicroRNAs (miRNAs) are a type of small noncoding RNAs that regulate gene expression at the posttranscriptional level and can influence significant biological processes. Arma chinensis (Hemiptera: Pentatomidae) is a predaceous insect species that preys upon a wide variety of insect pests. It is important to explore and understand the molecular mechanisms involving miRNAs in regulating developmental and other gene expression for beneficial insects. However, examination of miRNAs associated with Hemiptera, especially predatory bugs, has been absent or scarce. This study represents the first comprehensive analysis of predatory bug A. chinensis encoded miRNAs through high throughput sequencing and predicts genes and biological processes regulated by the newly identified miRNAs through analyzing their differential expression in and across five nymphal instars. A total of 64 A. chinensis miRNAs, including 46 conserved miRNAs and 18 novel miRNAs, were identified by analysis of high throughput sequence reads mapped to the genome. A total of 2913 potential gene targets for these 64 miRNAs were predicted by comprehensive analyses utilizing miRanda, PITA, and RNAhybrid. Gene Ontology annotation of predicted target genes of A. chinensis suggested the key processes regulated by miRNAs involved biological processes, regulation of cellular processes, and transporter activity. Kyoto Encyclopedia of Genes and Genomes pathway predictions included the Toll and Imd signaling pathway, Valine, leucine and isoleucine degradation, Steroid biosynthesis, the AGE-RAGE signaling pathway in diabetic complications, and Alanine, aspartate and glutamate metabolism. This newly identified miRNAs through analyzing their differential expression, assessment of their predicted functions forms a foundation for further investigation of specific miRNAs.

Role of four Phytoseiid mite species and Acarophagous Ladybird, Stetlrorus gilvifrons (Mulsant) as Bioagents of the Two Spotted Spider Mite Tetranychus urticae Koch

Predaceous insects and mites are important biological control agents of the two spotted spider mite Tetranychus urticae Koch. Biology and life table parameters of Stethorus gilvifrons Mulsant, Phytoseiulus persimilis A.-H., Neoseiulus cucumeris (Oud.), Typhlodromips swirskii (A.-H.) and Euseius scutalis A.-H. fed on T. urticae immature was studied at 28 ±1°C. Their female life cycle and life span averaged 17.66, 5.80, 4.40, 6.26 & 6.26 days and 47.60, 19.13, 38.00, l3.20 & 23.93 days, respectively. During its life span, average female fed on 1647. I 3, 343.53, 353.53, 345.66 & 200.33 with a daily rate 34.60, I 7.96, 9.30, 8.00 and 8.37 T. urticae immature respectively. The net rate of natural increase (rm) and the finite rate of increase (λ) of the aforementioned predators were 0.139, 0.294, 0.349, 0.26 I & 0.229; and 1.15, 1.34, 1.41, 1.29 & 1.25, respectively. These of T. urticae were 0.222 and 1.24, respectively.

Role of Stethours gilvifrons (Mulsant) as Biological Control Agents of the Two Spotted Spider Mite Tetranychus urticae Koch

Predaceous insects is an effective important biological control agents of feeding on Tetranychus urticae Koch and decreasing the number during 2018 season to study the optimal predator: prey ratios for the release of Stethours gilvifrons (Mulsant) sacond larvae and adult stage for controlling the T. urticae on cottonplants Gossypium burbadense L. The obtained results showed that the effective control was gained after 12 days from released the second larvae and adult of the S. gilvifrons predatorwhen the predator: prey ratios were 1:15and1:25 respectively. The regression analysis between predator: prey ratios of S. gilvifrons (larvae and adults) reduction percentages cleared that there were negatively high relationship of larvae and adult predators and prey ratios, which means that the reduction rate was increased with lower predator : prey ratios and vice versa .The results assured that the best control of T.urticae populations under semi field conditions was cleared by using the lower predator prey ratios (1:15 and 1:25) . Finally the predators can be used as biological control agents for T.urticae in cotten plantation under field conditions. The regression analysis between P: p ratios of S. gilvifrons adults and reduction percentage of the T.urticae mites , data showed there were negatively highly relationship of both predators larvae and adult which means that the reduction rate was increased with lower P: p ratios and vice versa.

Avantium and R&F Chemical partner on PEF applications in Korea

It is well known that most arthropod predators are generalist feeders and consume a wide range of prey species. As such, intraguild predation (IGP) is prevalent in virtually every agroecosystem. A polymerase chain reaction (PCR) assay was developed to examine the gut contents of predators that inhabit Arizona cotton for the presence of the DNA of green lacewing, Chrysoperla carnea, a common lower-tiered member of the predator community. A total of 1440 predators were captured using both a sweep net and whole plant sampling method. The gut content analyses revealed that over 10% of the predator population contained C. carnea DNA in their gut. Of these, IGP on C. carnea was detected almost twice as frequently in predaceous insects as spiders. The assassin bugs frequently encountered in cotton, Zelus renardii and Sinea confusa and orb-weaving spiders (Araneidae) were frequently identified as apex predators of C. carnea. These data provide a better understanding of predator–predator interactions in cotton and highlight areas for future research. That is, more thorough studies are needed to quantify prey selection of apex predators. Apex predators that frequently engage in IGP could be potentially antagonistic to the biological services rendered by the entire predator community.

Classical insect biocontrol in North America, 1985 to 2018: a pest control strategy that is dying out?

Abstract This review is a summary of a new catalog on the use of classical biological control of arthropods in North America since 1985. In this new catalog, we reviewed releases since 1985 of exotic parasitoids and predaceous insects for classical biocontrol of invasive insects in Canada, Mexico, the continental USA, and U.S. overseas areas. Here, we summarize the catalog and extract trends in usage and success. Trends measured included numbers of agents released, numbers established, numbers having a positive impact on the target pests, and numbers of projects initiated, which allow readers to determine if use of this method of insect control has increased, declined, or held steady over the studied period. These trends provide understanding of the social relationship between countries and this form of pest control and how it has changed over time. During this period, there were 208 parasitoid releases (=species × country or overseas U.S. area) compared to 29 for predators. Of these parasitoid releases, 112 (53.8%) resulted in establishment, and 57 (27.4%) controlled the target pest partially or completely. Most releases occurred in the USA, and we calculated trends for parasitoids per 5-year period. From 1985 to 2018, numbers of parasitoids released (counting the continental USA, Hawaii, Puerto Rico, Guam, Marianna Islands, and the U.S. Virgin Islands separately) declined per 5-year interval from 52 to 7, an 86.5% reduction. The percentage of newly released parasitoids that established increased from 42 to 71%, a 1.7-fold increase, but the number of newly established parasitoid species that reduced their target pests declined from 73 to 40%. Also, the number of new projects initiated per 5-year period decreased from 31 to 5, an 84% decrease. The percentage of projects reducing their target pests showed no strong trend: 1985–1989, 42% vs. 2010–2014, 60%. Chalcidoids were most effective; of 119 chalcidoid releases, 76 (63.9%) established, and 45 (37.8%) reduced their target pests. Chalcidoids, based on available literature host records, were not more specific than less effective groups, despite the view that higher efficacy would be associated with greater host-specificity. The predominance of chalcidoids is likely due to their frequent use against scales, whiteflies, mealybugs, aphids, and psyllids, which are tightly associated with live plants, tend to be moved frequently internationally, and often become agricultural pests in areas where they are introduced.

Identification and field verification of aggregation-sex pheromone from the predaceous bug, Arma chinensis

Arma chinensis is a predaceous insect species that can effectively suppress a wide range of agricultural and forest insect pests in the orders Lepidoptera, Coleoptera, Hymenoptera and Hemiptera in Northeast Asia. Adult A. chinensis males produce an aggregation-sex pheromone from dorsal abdominal glands and artificial aggregation-sex pheromone can attract adults of both sexes. The aggregation-sex pheromone consists of (E)-2-hexenal, (E)-2-hexen-1-ol, benzaldehyde and benzyl alcohol. Both antennae and proboscises of A. chinensis females and males responded to components from male dorsal abdominal gland extracts. (E)-2-hexenal and benzaldehyde elicited significantly higher EAG responses than those with (E)-2-hexen-1-ol and benzyl alcohol. Benzyl alcohol elicited the weakest EAG responses, although benzyl alcohol was the most abundant of the four major components in male dorsal abdominal gland extracts. A field bioassay using trap catches demonstrated that (E)-2-hexenal and benzyl alcohol were key components of the pheromone for catching conspecific adults. Single pheromone components were the least attractive to A. chinensis in the field.

POPULATION FLUCTUATION OF SOME PIERCING-SUCKING INSECTS AND ITS RELATION TO ASSOCIATED PREDATORS AND THE PREVAILING WEATHER FACTORS IN SOYBEAN FIELDS AT KAFR EL-SHEIKH GOVERNORATE

In Egypt, aphids, Aphis spp.; leafhoppers, Empoasca spp. and whitefly, Bemisia tabaci (Genn.) are the most important piercing-sucking insect pests infesting soybean plants and a good understanding of their population dynamics is essential to develop an integrated pest management strategy. Therefore, the population densities of these insects and its relation to the common associated predators and the prevailing weather factors were investigated in soybean fields at Kafr El-Sheikh Governorate for 2016 and 2017 seasons. Weekly counts of the considered insects per 15 leaves indicated that whitefly was the most abundant species followed by leafhoppers, while aphids were the least one. Whitefly and leafhoppers appeared on soybean plants all over the growing season. The maximum density of whitefly took place from mid-June to late July in the first season and from the second half of July to the first half of August in the second season. The high number of leafhoppers occurred in the period from mid-July to mid-August for the first season and during August in the second season. Aphid population appeared only in two periods with very low numbers for every season. In the first season, the first period occurred in the second half of June, while the second period took place in the first half of September. In the second season, the population appeared from late June to mid-July and from late August to mid-September. Also, three predaceous insect species: Chrysoperla carnea (Steph.); Coccinella undecimpun ctata L. and Orius spp. were observed on soybean plants. Ch . carnea was the most abundant predator, while C . undecimpunctata was the least one. The total of the predaceous insects attained the highest numbers during July in the first season and during July and August in the second one. The weather factors (temperature, relative humidity and wind speed) had insignificant effect on the cotton whitefly population in the two study seasons. As for leafhoppers, wind speed only had significant effect on the population activity in the second season. Temperature and wind speed in the first season and wind speed in the second season had highly significant effect on aphids activity in the first season. The effect of the predators on the insects was insignificant during the two seasons except effect of the predaceous insects on the leafhoppers which it was significant. The combined effect of both predators and the prevailing weather factors was more pronounced only on aphids in the first season and on leafhoppers in the second season. However, the gained results may provide valuable information for comprehensive integrated insect management of soybean.

Predatory hymenopteran assemblages in boreal Alaska: associations with forest composition and post-fire succession

ABSTRACTChanges to the fire regime in boreal Alaska are shifting the ratio of coniferous to deciduous dominance on the landscape. The increase in aspen and birch may have important effects on predatory hymenopteran assemblages by providing a source of extrafloral nectar and increasing prey availability. Furthermore, fire-induced changes in successional age alter habitat structure and microclimate in ways that may favor ants. This study is the first to characterize the influence of fire-related vegetation changes on boreal predatory hymenopteran assemblages. We compare the abundance, species richness, and composition of predatory hymenopteran assemblages among forests at different stages of succession and of varying post-fire tree species compositions. Ant assemblages were weakly related to forest composition, but ants were significantly more abundant and speciose in early-successional forests than in mid-late successional forests. In contrast, macropterous wasp morphospecies richness and abundance, and micropterous wasp abundance, were positively related to the basal area of aspen, but were not related to successional stage. The results suggest that shifts in boreal vegetation related to climate warming will result in changes to the predaceous insect community, with ants responding positively to disturbance and wasps responding positively to an increase in the representation of aspen on the landscape.

Important predaceous insects of citrus aphids (Hemiptera: Aphididae) in the north of Iran

ABSTRACT- Several species of aphids cause severe damage to citrus in the north of Iran. Predatory insects play an important role in biological control of the pests in citrus orchards. In this study, potential predatory insects of citrus aphids, Aphis spiraecola, A. gossypii and Toxoptera aurantii, were identified and their seasonal population dynamics on Citrus unshiu and C. sinensis were investigated during 2016-2017. Overall, four species were identified as dominant predatory insects of citrus aphids in Mazandaran province including Xanthogramma pedissequum (Syrphidae), Scymnus subvillosus, Coccinella septempunctata (Coccinellidae), and Aphidoletes aphidomyza (Cecidomyiidae). Among these species, X. pedissequum and S. subvillossus were more abundant predators in the C. sinensis and C. unshiu orchards compared to the two other species. The predatory insects were observed when means of environmental temperature was about 15-20oC. Population fluctuations, population densities and presence periods of the predatory insects were different on the two host plants. Results of this study can be used in integrated pest management programs of citrus aphids in citrus orchards in the north of Iran.

Predaceous insects may limit algal grazers in high-nutrient environments: implications for wastewater remediation in open bioreactors

Algal biofuel has potential as a source of renewable fuel and a tool for wastewater remediation. Open algal bioreactors fertilized with wastewater can have net energy gain but are vulnerable to colonization by algal grazers. However, colonizing predaceous insects may limit grazer impacts on algae. Here, we investigate the effects of grazers, predators, and invading algae species on algal production and community structure in high-nutrient environments. First, we grew diverse algal assemblages in treated municipal wastewater in a greenhouse with Daphnia grazers and different insect predators that were added experimentally. When Daphnia were present without predators, they eliminated suspended algae. But, dragonfly larvae [Odonata: Libellulidae] and backswimmers [Hemiptera: Notonectidae], but not larval diving beetles [Coloeoptera: Dytiscidae], suppressed Daphnia allowing suspended algae to persist. Second, we grew Chlorella algae in field tanks that were open or protected from natural invertebrate colonization and half the tanks received wild-collected plankton in a factorial design. Mosquito larvae [Culex sp.] readily colonized open tanks and reduced algal mass and dissolved phosphorus concentrations. Colonist addition to open tanks shifted algal functional and taxonomic composition but did not impact suspended algal production. Our study indicates that large numbers of grazer individuals can rapidly colonize open bioreactors. Experimentally added and naturally colonizing grazers altered algal community structure and reduced algal standing crops but may also aid in nutrient removal from wastewater-fed bioreactors. Effective operation of open algal bioreactors must consider cultivated algae species’ vulnerability to competition and local grazers as well as the ability of potential predators to both naturally disperse into bioreactors and to control grazers.

Yield Losses in Transgenic Cry1Ab and Non-Bt Corn as Assessed Using a Crop-Life-Table Approach.

In this study, we constructed crop life tables for Bacillus thuringiensis Berliner (Bt) Cry1Ab and non-Bt corn hybrids, in which yield-loss factors and abundance of predaceous arthropods were recorded during 2 yr at two locations. Corn kernel/grain was the yield component that had the heaviest losses and that determined the overall yield loss in the corn hybrids across years and locations. Yield losses in both corn hybrids were primarily caused by kernel-destroying insects. Helicoverpa zea (Boddie) and Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) were the key loss factors at one location, while at the other, the key loss factor was the silk fly larvae, Euxesta spp. (Diptera: Ulidiidae). Although the realized yield of corn grains was not different (P > 0.05) between Cry1Ab and non-Bt corn hybrids, the Bt corn hybrid reduced (P < 0.05) the damage by H. zea and S. frugiperda in three of the four field trials, particularly at the location where Lepidoptera were the key loss factors. As expected, no reduction in the abundance of predaceous arthropods was observed in Cry1Ab corn fields. Various species of natural enemies were recorded, particularly the earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae), which was the most abundant and frequent predaceous insect. These results indicate that integration of pest management practices should be pursued to effectively minimize losses by kernel-destroying insects during corn reproductive stages when growing non-Bt or certain low-dose Bt corn cultivars for fall armyworm and corn earworm, such as those producing Cry1Ab or other Cry toxins.

Field Trapping of Predaceous Insects With Synthetic Herbivore-Induced Plant Volatiles in Cotton Fields

Nine herbivore-induced plant volatiles (HIPVs) and one methyl jasmonate were field-tested for their attractiveness to the main predators in cotton fields of North China in 2 yr. The main predators including ladybird beetles (Propylaea japonica (Thunberg), Harmonia axyridis (Pallas)), green lacewings (Chrysoplera sinica (Tjeder), Chrysopa spp.), predatory bugs (Geocoris pallidipennis (Costa), Orius spp., Nabis spp.) and spiders (Misumenops tricuspidatus (Fabricius), Erigonidium graminicolum (Sundevall)) were investigated. Two-way ANOVA indicated that the volatile compound, year, and the volatile compound × year interaction affected the behavioral responses of predators. It was found that indole significantly attracted the ladybird beetle P. japonica, H. axyridis. Linalool could attract P. japonica. Green lacewing C. sinica was significantly attracted by α-pinene and β-pinene, whereas indole significantly attracted Chrysopa spp. Methyl jasmonate and α-pinene showed significant attraction to small-flower bug Orius spp. In addition, the attraction of α-humulene to C. sinica, attractiveness of β-pinene to Orius spp. and Chrysopa spp., were observed only in one of the two years. However, the big-eyed bug G. pallidipennis, damsel bug Nabis spp., spiders M. tricuspiata and E. graminicolum did not respond to any of the tested HIPVs. These results are discussed with respect to possible applications of a synthetic attractant for main predators in cotton fields.

The Role of Predators Insects in Regulating Population Densities of Certain Piercing Sucking Pests on Squash Plants in Egypt

Studieswere carried out at Diarb Negim, Sharkia governorate during two successiveseasons 2014-2015 and 2015-2016. Obtained results showed that in autumnplantation, there were two peaks of Aphis gossypii (Glover) on squashplants, one peak at last week ofNovember and other at third week of December in 2014 season. On the other hand,Bemisia tabci (Genn.) had three peaks, in second week of November, firstweek of December and third week of December in 2014 season and two peaks ofinfestation in fourth week of November and December in 2015 season of autumnplantation while, three peaks in summer plantation were obtained on fourth weekof (April &May) and second week of June in 2015 season respectively.Investigation revealed that, squash plants infested by few numbers of thripsduring autumn plantation throughout the two seasons. Statistical analysis ofthe obtained data cleared highly negative correlation between aphid&whitefly and temperature in autumn plantation in both seasons. Also, themean R.H showed a positive significant correlation on population density of A.gossypii in second season 2015 of autumn plantation. In summer plantation,the minimum R.H% showed a negative correlation with Orius spp.population and a positive significant correlation with C. carnea populationin the first season 2015. The predaceous insects found associated with pericingsucking pests were Orius spp., Coccinella undecimpuncta L.,Chrysoperla carnea Steph., Metasyrphus corolla F. and few number of Paederusalferii (Koch ) and true spider. Theresults revealed that Orius spp. had three peak in two season in autumnplantation, in first and third week of November, and third week of December inboth seasons respectively. Meanwhile there was two peaks in first week of Mayand third week of June in 2015 season of summer plantation. Chrysoperlacarnea had two peaks in autumn plantation during two seasons, third week ofNovember, second week in December in 2014 and fourth week of November, thirdweek of December in 2015 respectively. Also two peaks in summer plantationduring 2015 season in first week of April and second week of June.

Cereal Aphid Species (Homoptera : Aphididae) Infesting Wheat Plants and their Aphidophagous Insects at El-Khattara District, Sharkia Governorate, Egypt

Studies on cereal aphids infesting wheat plants and their aphidophagous insects were carried out in newly reclaimed sandy area at El-Khattara district, Sharkia Governorate, Egypt during 2015-2016 and 2016-2017 growing seasons.The obtained results are summarized as follows:Four aphid species, i.e., Shizaphis graminum (Rondani), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (Linnaeus) and Macrosiphum avenae (Fabricius) were found infested wheat plants.Cereal aphids infested wheat plants from the first week of January till the last week of April. The highest populations of aphids were recorded in the first week of March and in the second week of April with counts of 711 and 1503 individuals/ sample in the first and second seasons, respectively.Six predaceous insect species belonging to four orders and five families were surveyed associated with aphid species infesting wheat plants. Coleopterous species were the most dominant, followed by the neuropterous ones, with general relative densities of 41.70 and 21.10 % of the total recorded predators, successively. Among all recorded predaceous species, Chrysoperla carnea (Stephens) , Coccinella undecimpunctat L., and Coccinella septempunctata L., were the most dominant species, comprised 21.10, 15.68 and 15.26 % of the total count of the predators, respectively. The total recorded predators showed that means of 1:61.62 and 1:118.73 predators: prey ratios in the first and second seasons, respectively.Five species of hymenopterous parasitoids were emerged from mummified individuals of cereal aphids, namely, Diaeretiella rapae (M’Intosh), Aphidius colemani Viereck, Aphidius matricariae Haliday, Ephedrus sp. and Praon sp. The most dominant parasitoids were D. rapae and A. colemani with general relative densities of 35.32 and 27.12% respectively. The fluctuations of the total percentages of parasitism indicated three peaks in the first season and two ones in the second season. The mean percentage of parasitism during the first season was relatively high (6.41%) in comparison with that in the second one (3.60%).The correlation between cereal aphids populations and percentages of parasitism in both seasons were positive high significant

SURVEY OF MAIN INSECT SPECIES ASSOCIATED WITH CERTAIN MEDICINAL AND AROMATIC PLANTS AT AWLAD-SAKR DISTRICT, SHARKIA GOVERNORATE

The present study was conducted to survey the economic insect pests infesting some medicinal and aromatic plants i.e., roselle (Hibiscus sabdariffa L.), thyme (Thymus vulgaris L.) and sweet basil (Ocimum basilicum L.) and their common associated natural enemies as well as pollinators and visitors at Awlad–Sakr district, Sharkia Governorate, Egypt during the two summer growing seasons 2015 and 2016. The results recorded that 29 insect species belongs to 25 families and 10 orders associated with the three studied medicinal and aromatic plants. Destructive insects comprised 17 species belongs to 15 families and 8 orders. Predaceous insects composed 8 species of 6 families and 5 orders. Parasitoids were represented by only one species on sweet basil. Results also cleared that pollinators and visitors included 3 species belong to 3 families and 2 orders. Aphis gossypii Glover, Bemisia tabaci (Genn.) and Empoasca decipiens (Paoli) were the most dominant insect pests on roselle, thyme and sweet basil plants. A. gossypii was the main insect pest on roselle exhibited by general total percentage of 38.19% in the two seasons and B. tabaci of 51.40% on thyme and E. decipiens of 60.48%on sweet basil. The main predaceous insect recorded on the three aforementioned plants was Coccinella undecimpunctata L., representing 72.53, 56.18 and 30.38%, respectively. Yellow sticky board trap proved to be the most effective method for collecting E. decipiens, B. tabaci, Thrips tabaci Lind., Musca domestica L., C. undecimpunctata, Metasyrphus corollae (Fabr.), Chelonus ininatus L. and Culiseta longiarolata (Macq.), while thesweeping net was the pest methodfor collecting Cosmolyce baeticus L., Nezara virdula L., Aphis mellifera L., Philanthus abdelkader Luc. and Egyptica legyptius.Plant sampling technique was effective for estimating A. gossypii and Iceria aegyptiac Douglas.