Egg Density Research Articles

Eggplant-garlic intercrops reduce the density of Tetranychus urticae on eggplant and improve crop yield.

Diversification of cultivation systems plays a critical role in ecosystem functions such as pest control, diversity of beneficial arthropods, and soil fertility. Repellent plants (releasing volatile organic compounds as arthropod repellents and providing alternative prey for natural enemies) may be used in an intercropping system for pest control; however, little is known concerning their relative priority. In this study, the impact of intercropping eggplant (E) (Solanum melongena L.) and garlic (G) (Allium sativum L.) in three designs -with row ratios of 4E:4G, 4E:8G, or 4E:12G -was assessed on the density of the two-spotted spider mite (TSSM) (Tetranychus urticae Koch), the abundance and diversity of predators, and crop yields, compared with the sole crops over two growing seasons of 2019 and 2020. In three intercrops, a significant decrease in the density of TSSM egg and mobile stages was observed compared with the sole eggplant at each growth stage of eggplant. The damage index by TSSM on eggplants was lower in intercrops (8.1-11.5%) compared with sole crop (37.0-40.3%) in the two seasons. The abundance of Stethorus gilvifrons was lower in the three intercrops than in the sole crop on the blooming-initial fruit set and the fruit development stages of eggplant. The density of Orius niger was higher in the three intercrops compared with the sole crop on vegetative growth and flowering to initial fruit set stages of eggplants. The abundance of Chrysoperla carnea was not significant among treatments. Greater values of the Shannon diversity index and the Pielou's evenness index for the construction of TSSM predators were recorded in the three intercrops compared with the sole eggplant over both growing seasons. In addition, a significant improvement in the yield per unit area of eggplant and garlic was obtained in intercrops compared with sole crops. These results indicate intercropping eggplant and garlic was a practical solution for reducing TSSM on eggplant, promoting the abundance of predators, and improving the crop yields of eggplant and garlic compared with the sole crops.

Emerald ash borer (Agrilus planipennis) infestation bioassays and metabolic profiles of green ash (Fraxinus pennsylvanica) provide evidence for an induced host defensive response to larval infestation

IntroductionLarvae of the invasive emerald ash borer [EAB, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)], kill over 99% of green ash (Fraxinus pennsylvanica Marshall) trees they infest, yet a small percentage of green ash (“lingering ash”) survive years of heavy EAB attack. In the face of an ongoing invasion that threatens multiple North American Fraxinus species with extinction, any evidence for reproducible defensive responses in the native species merits investigation.MethodsWe evaluated the capacity of three families of green ash F1 progeny to kill EAB larvae when challenged in greenhouse studies by infestation with a uniform density of EAB eggs followed by dissection 8 weeks post-infestation and comparison of the host metabolomic profiles.ResultsThe mean proportions of host-killed larvae in the two families of F1 progeny from lingering ash parents were significantly higher than that of host-killed larvae in the family of F1 progeny from susceptible ash parents (p < 0.001). Untargeted metabolomics comparing F1 progeny in the quartile with the highest percent host-killed larvae (HHK) to F1 progeny in the quartile with the lowest percent host-killed larvae (LHK) and to the uninfested F1 progeny within each family revealed evidence for induced biochemical responses to EAB. Infested trees produced significantly higher levels of select secoiridoids than uninfested trees, and LHK progeny produced significantly higher levels of select secoiridoids than the HHK progeny. HHK progeny produced significantly higher abundances of three metabolites annotated as aromatic alkaloids than the LHK and uninfested individuals.DiscussionBased on these results, we hypothesize that green ash responds to EAB infestation. However, only certain trees have the genetic capacity to tailor a response that kills enough EAB larvae to prevent lethal damage to the vascular system. Rigorous tests of this hypothesis will require 15–20 years of additional crossing, phenotyping, and omics analyses. The results of this investigation will encourage the establishment and continuation of breeding programs that, in concert with biocontrol and management, could provide trees that slow, if not halt, the decimation of the Fraxinus gene pool. At the same time, ongoing work on host-insect interaction will contribute to our understanding of how forest trees recognize and defend themselves against phloem-feeding insects.

Field and laboratory validation of new sampling gear to quantify coregonine egg deposition and larval emergence across spawning habitat gradients

The influence of habitat and environmental conditions on Great Lakes coregonine reproduction is not well described, in part, because we lack sampling gears for early life stages that are effective across habitats. We designed new egg and larval emergence traps to quantify coregonine reproductive success across variable depths and substrates and tested them in laboratory and field settings. In the laboratory, our new metal ring egg traps had greater egg retention (94–100%) and faster post-catch processing (5–7 min) relative to a commonly employed fiber mat trap (30–67% and 30–60 min). In Lake Ontario’s Chaumont Bay, egg densities for lake whitefish Coregonus clupeaformis (0–5,832 eggs m−2) and cisco Coregonus artedi (0–426,501 eggs m−2) measured with metal ring traps (n = 112) varied across habitats but were greatest between 2–5 m on rock and dreissenid mussel substrates. Emergence traps used an inverted cone, fine mesh, and a clear collection chamber to capture positively phototactic emerging larvae. In the laboratory, traps captured 69–80% of emerged larvae. In Chaumont Bay, emergence traps deployed for 21 days after ice out caught only cisco larvae. Emergence rates varied across habitats (0–118 larvae m−2 day−1, n = 85) but were highest on dreissenid mussel reef substrate. Our samplers improved processing efficiency and facilitated large sample sizes to quantify variability in egg deposition densities and emergence rates across habitats. These methods can advance coregonine conservation by determining how anthropogenic changes to habitat and environmental conditions influence incubation success.

Effect of cage space allowance on egg production, egg quality, immune responses and anti-oxidant variables in White Leghorn layers

A comprehensive study was conducted to optimise cage space allowance (CSA) for White Leghorn (WL) layers (65-80 weeks of age). For the purpose, a total of 900 layers were housed in California colony cages in an open sided poultry house at three different CSA (422, 563, 844 cm2/bird). Each of the CSA was studied with 20 replicates. The daily egg production (EP), feed intake (FI), feed efficiency (FE, FI/egg mass) and egg quality traits were recorded at the end of each 28d interval. Anti-oxidant responses like lipid peroxidation (LP) and glutathione peroxidase, glutathione reductase and superoxide dismutase in blood were measured at 80 weeks of age. Similarly, the antibody titres against ND vaccine and cell mediated immune response (CMI) against PHA- P were measured at 80 weeks of age. The variation in CSA did not influence EP, egg mass, weight gain and egg shell thickness. The FI reduced and FE improved with reduction in CSA. However, the egg density and egg shell percentage increased with increase in CSA. The LP was higher and the activities of anti-oxidant enzymes were lower at 422 cm2/bird as compared to the higher space allowances. No effect of CSA on ND titre was observed, while the CMI response was higher at 844 cm2/ bird than the other two CSA. It could be concluded that, though the FE was better at 422 cm2/b, the trends of shell quality traits and antioxidant variables indicated 546 cm2/bird as requirement for WL layers in open sided poultry house under tropical regions.

Survey on the quality of outlet biosolids and sludge heavy metals in the wastewater treatment plants of Mazandaran province

Background: Sewage sludge is rich in fecal coliforms, Salmonella, parasite eggs, and heavy metals that can cause disease in humans. The aim of this study was to evaluate the quality of outlet biosolids and sludge heavy metals in the wastewater treatment plants (WWTP) in Mazandaran province and to compare them with the Environmental Protection Agency (EPA) standards. Methods: This study was carried out on the sludge of the treatment plants of Sari, Joybar, Babol, Babolsar, Nowshahr, and Nowshahr-Chalus sludge compost plants. In this study, physical, chemical, and biological properties of sludge samples including retention time, pH, total solids (TS), color, heavy metals (copper, zinc, nickel, cadmium, and chromium) as well as the density of fecal coliform, Salmonella and parasite eggs were determined and reported. Results: Biosolids of Joybar, Babol, Babolsar, and Nowshahr-Chalus WWTP in terms of parasite eggs were in class A. Biosolids of Sari WWTP in summer after drying off naturally were located in Class A, and in summer and spring, were located in Class B based on the US EPA criteria. The average concentration of heavy metals (copper, zinc, nickel, cadmium, and chromium) was lower than the EPA standard. Conclusion: The results showed that mostly the treated sewage sludge in Mazandaran WWTPs were in Class B of the EPA guideline. The concentration of heavy metals in the biosolids of these WWTPs is lower than the EPA regulation and the use of these biosolids in agriculture is not limited for these metals.

Spawning ecology of the Saint Paul's Gregory Stegastes sanctipauli, a damselfish endemic to the remote St. Peter and St. Paul's Archipelago.

We studied the spawning ecology of Stegastes sanctipauli, a damselfish endemic to the small and remote St. Peter and St. Paul's Archipelago (Brazil), aiming to determine the main correlates of reproductive success, as inferred from rates of egg losses along a spawning season. New clutches appeared mostly in the last quarter moon, when egg predation intensified. Predation by heterospecifics, particularly Halichoeres radiatus (Linnaeus, 1758), accounted for most egg losses, while filial cannibalism showed negligible influence. Predation pressure was highest for larger nests with higher initial density of eggs. Hatching of eggs occurred close to the new moon (i.e. ~5 days after spawning). Most nests occur in shallow reefs (<16 m depth), where main food resources for adults (turf algae) are concentrated, but abundance of egg predators, particularly H. radiatus, is also highest. This later result suggests that the spawning activity of S. sanctipauli is influenced by the trade-offs between food accessibility by adults and egg predation risk. The patterns recorded here are similar to those known for other tropical damselfish species and may reflect strategies for attenuating predation pressure over new fry and eggs.

Identification of Risk Areas of Dengue Transmission in Culiacan, Mexico

Dengue is a public health problem in more than 100 countries around the world and in virtually the entire region of the Americas, including Mexico. Mosquitoes of the genus Aedes aegypti transmit dengue; its reproduction requires certain geographical, epidemiological, demographic and socioeconomic conditions. Detailed information on socioeconomic, epidemiological and entomological data is available, but detailed meteorological information is not. The objective of this study was to identify the areas of risk of dengue transmission for each month of the year based on environmental, social, entomological and epidemiological information from 2010 to 2020, in Culiacan, Mexico. LST, NDVI and NDMI were calculated from Landsat 8 satellite images with remote sensing techniques. Additional variables were human population density and overcrowding; mosquito egg density from positive ovitraps; and probable cases of dengue. A descriptive analysis of the study variables and a multiple linear regression analysis were performed to determine the significant variables. In addition, a multicriteria spatial analysis was applied through the AHP technique to identify areas at risk of dengue transmission. The results revealed that the variables NDVI, NDMI and overcrowding were not significant; however, the LST, population density, egg density per positive ovitrap and probable cases were. The highest population in the transmission risk areas was in November, and the highest transmission area was identified in October. In conclusion, it was possible to identify which of the study variables were significant; in addition, monthly maps of risk areas of dengue transmission for Culiacan were obtained. Each geographical area had its own characteristics that influenced, in one way or another, the incidence of dengue, highlighting that the strategies for control of dengue must be specific to each region.

Functional response of an egg parasitoid, Trichogramma chilonis Ishii to sublethal imidacloprid exposure.

The effectiveness of a biological control agent depends on how well it can control pests and how compatible it is with pesticides. Therefore, we reported the multigenerational effect of a commonly used insecticide, imidacloprid, on the functional response of a widely acclaimed egg parasitoid, Trichogramma chilonis Ishii, to different densities of the host Corcyra cephalonica Stainton eggs. The study investigated the outcomes of the median lethal concentration (LC50 ) and sublethal concentrations (LC5 , LC30 ), along with control treatments for five continuous generations (F1 to F5 ). The results showed that the F5 generation of LC30 , both of the F1 and F5 generations of LC50 , and the control all had a Type II functional response. A Type I functional response was exhibited for the F1 generation of LC30 and both generations of LC5 . The attack rate on host eggs treated with LC5 and LC30 did not change (decrease) with the shift in the type of functional response as compared to the control. A significant increase in the searching efficiency (a) was observed in the later generation (F5 ) under the exposure of LC5 and LC30 imidacloprid concentrations. A lower handling time (Th ) in both generations of the LC5 followed by LC30 treated individuals was observed when compared with the control and LC50 treatments. The per capita parasitization efficiency (1/Th ) and the rate of parasitization per handling time (a/Th ) were also considerably higher in both the generations of LC5 and LC30 than in the control and LC50 , thereby implying positive effects of imidacloprid on the parasitization potential of T. chilonis. Altogether, these multigenerational outcomes on the functional response of T. chilonis could be leveraged to control the intractable lepidopteran pests under the mild exposure of imidacloprid in integrated pest management (IPM) programs as well as in the mass rearing of the parasitoid, T. chilonis. © 2023 Society of Chemical Industry.

Density of egg interior: Looking inside an egg while keeping it intact

Density of egg interior (Di) can be considered as universal index of the quality characteristics of the whole egg. Here, we implemented a theoretical and experimental approach to developing a method for non-invasive estimation of Di. The derived equation showed its dependence on the egg density (D) and the content of the shell in the egg, the latter being assessed as weight and volumetric ratios. We found that, for a fairly accurate prediction of Di, it is sufficient to include two parameters in the calculation, i.e., D and the non-destructive shell deflection. These were combined into one empirical equation that showed the calculation accuracy within this experiment at the level of R = 0.966. Determination of Di using non-destructive methods will allow for developing a number of applications, e.g., pre-incubation egg sorting, determining the conditions and duration of egg storage, and the quality rating of table eggs by internal contents.

Parasitism of Telenomus remus Nixon on Spodoptera frugiperda J.E. Smith and acceptability of Spodoptera littoralis Boisduval as factitious host

The egg parasitoid Telenomus remus has emerged as one of the potential candidates for use in biological control of the of the fall armyworm, Spodoptera frugiperda in Africa. However, its uses in biological control require a better understanding of its biology and the development of a cost-effective mass production. We firstly determined how T. remus reacts to an increasing S. frugiperda egg density. Subsequently we identified its preference for parasitism as a function of S. frugiperda egg age. Finally, we assessed the acceptability of Spodoptera littoralis as a factitious host for T. remus rearing. The number of eggs parasitized by T. remus increased as the egg density increased. Competition between T. remus females resulted in a male-biased sex ratio. Regarding host-eggs age, T. remus females prefer 1-day-old eggs over 2- or 3-day-old eggs. With respect to host acceptability, T. remus was shown to parasitize S. littoralis eggs and produce viable offspring. Although, T. remus tended to parasitize fewer S. littoralis than S. frugiperda eggs it can be used as a factitious host for the mass multiplication of T. remus in a biological control program.

KAPASITAS POTENSI PARASITISME Trichogramma sp. (Hymenoptera: Trichogrammatidae) TERHADAP Corcyra sp.

Parasitism research Trichogramma sp. (Hymenoptera: Trichogrammatidae) has been carried out with the aim of studying the functional response of the parasitoid Trichogramma sp. Functional response is one measure to determine the effectiveness of a predator or parasitoid as an agent in biological control, so that it can express a change in the number of preys attacked by individual predators. Temperature is one of the most important host-parasitoid interactions in functional responses. The method used in the parasitoid parasitism Trichogramma sp. on the host Corcyra sp. using four levels of egg density Corcyra sp. with two different temperature treatments (27OC and room temperature). The results show the functional response model of the parasitoid Trichogramma sp. against its host Corcyra sp. described in the type I model. Parasitization level of Trichogramma sp. showed the same results for both temperature treatments, however, it also shows differences in the speed of predation. It also showed linearity between the parasitoids Trichogramma sp. with the host Corcyra sp. Parasitism rates are still increasing, along with an increase in host density. This research can be a starting point to improve the control of Corcyra sp. using the parasitoid Trichogramma sp. in the field.

Effects of co-occurrence and intra- and interspecific interactions between Drosophila suzukii and Zaprionus indianus.

In drosophilids, competition and coexistence can impact survivorship, growth, and reproductive output. Here, we evaluated direct competition between two co-occurring fruit flies, the spotted-wing drosophila Drosophila suzukii and the African fig fly Zaprionus indianus, comparing results from field collections with laboratory experiments. Field collections were conducted to evaluate co-occurrence between species. In the laboratory, different densities of eggs of each species were provided an artificial diet, and intra- and interspecific densities were evaluated regarding biological traits such as development and fecundity. Field collections showed a prevalence of Z. indianus, followed by other drosophilid species, including D. suzukii. Pupal survival and adult emergence were higher in D. suzukii than in Z. indianus at both intra- and interspecific densities, with decreasing values in response to increased densities. Fecundity did not differ significantly for either species at different intraspecific densities, but when reared together at different densities, Z. indianus was significantly more fecund than D. suzukii. Development time showed no significant difference at intraspecific densities, but when reared together, Z. indianus had longer development times than D. suzukii. Leslie Matrix projections indicated that D. suzukii showed practically the same dynamics at intraspecific and interspecific densities, with increasing oscillations at low and intermediate densities and decreasing oscillations at high densities. Zaprionus indianus showed a similar oscillation to D. suzukii, except at intermediate intraspecific densities, when the pattern was cyclic. Low interspecific densities resulted in decreasing oscillations. In the two-choice oviposition bioassays, D. suzukii females showed no significant preference for diets previously infested or not with either conspecific or heterospecific eggs at different densities. Understanding competitive interactions between co-occurring heterospecific species should be considered when establishing management tactics for spotted-wing drosophila.

Diversity of life history and population connectivity of threadfin fish Eleutheronema tetradactylum along the coastal waters of Southern China

Understanding the diversity of life history, life stage connectivity and population is essential to determine the spatial scale over which fish populations operate. Otolith microchemistry analysis is a powerful tool to elucidate the life history and population connectivity of fish, providing important insights to the natal origin and population structure. In this study, we used laser ablation inductively coupled plasma mass spectrometry to analyze the chemical composition of otoliths throughout the entire lifetime of endangered fourfinger threadfin species, Eleutheronema tetradactylum. We reconstructed the life history of E. tetradactylum from Southern China collected from different locations over a spatial scale of 1200 km. Sr:Ca and Ba:Ca ratios profiles from otolith core-to-edge analysis suggested two contrasting life history patterns. Based on the differences in early life stages, we identified some fish spending their first year in an estuarine environment with subsequent movement to marine coastal systems, while some fish remaining in the coastal systems throughout their entire early life history stages. The non-metric multi-dimensional scaling showed a strong overlap in otolith core elemental composition, indicating a large-scale connectivity in the life history of E. tetradactylum. The immature fish from different natal origins mixed to a large extent when they fed and overwintered in the extensive offshore waters. Clustering of near core chemistry pointed to three possible sources of nursery for the threadfin fish. This study demonstrated the diversity of life history patterns of E. tetradactylum in Southern Chinese waters. Restoration in egg and larvae densities in coastal waters and estuaries may enhance their population abundances.

Ichthyoplankton and plastic waste drift in a river in the Amazon Basin, Brazil

Egg and larvae drift is a key mechanism for early fish stages to colonize nursery and growth areas and provides insights into ichthyofauna spawning times and spawning locations—crucial information for understanding fish biology. In the Tapajós River, Amazon Basin, no study has investigated the drift of ichthyoplankton along the hydrological phases nor the occurrence and dispersion of plastic waste associated with plankton. Thus, we aimed to present an overview of the spatio-temporal drift of ichthyoplankton and plastic waste in this river. Temporal sampling was carried out along a spatial gradient of approximately 300 km, covering different sectors of the river. Ichthyoplankton and plastic waste were captured through horizontal trawls on the subsurface of the water column for 10 min. Fish larvae belonging to 10 taxonomic orders and with an average size of 4.98 mm ± 3.14 mm were captured. Clupeiformes larvae occurred in all hydrological phases and reproductive peaks for other orders were recorded. Plastic waste was classified into 20 types according to color and shape and an average size of 1.55 mm ± 1.27 mm. Green fragments and blue filaments were the most abundant. We found the highest density of fish eggs and larvae drifting during the drought phase in stretches with greater environmental structure, whereas plastics were more abundant during the receding water phase in more turbulent stretches that have impacts from illegal mining. Simultaneous drift of ichthyoplankton and plastic waste was recorded in all hydrological phases and sampled sectors. This is worrying because, although we did not analyze the ingestion of plastics by fish larvae, plastic waste can enter the nursery areas of the Tapajós River and reduce the function of these areas for fish. Here we discover through the high densities of fish eggs and larvae deriving that the Tapajós River is an important reproduction site for ichthyofauna and that the presence of different landscape configurations prove to be a key factor in the dispersion, retention and development of ichthyoplankton and plastic waste.

Foraging behavior of Amblyseius swirskii (Acari: Phytoseiidae) feed on the invasive pest Tetranychus evansi (Acari: Tetranychidae) on tomato

The invasive tomato spider mite, Tetranychus evansi (Acari: Tetranychidae) is one of the major pests of the solanaceous plants worldwide. The phytoseiid predatory mite Amblyseius swirskii (Acari: Phytoseiidae) is one of the most commonly used predatory mites for augmentative biological control of several important pests in protected crops. Despite its frequent usage in a range of greenhouse crops including tomatoes, several biological characteristics and foraging behaviors of this predator such as functional and numerical responses, have not been studied on T. evansi. In this study, the functional and numerical responses of A. swirskii to four different biological stages (eggs, larvae, protonymphs and deutonymphs) of T. evansi were evaluated under laboratory conditions. The significantly negative P1 values and the type of functional response curves clearly indicate that A. swirskii exhibited a Type II functional response to T. evansi regardless of prey stage. The highest attack rate (α=0.070 h-1) and the shortest handling time (Th=0.426 h) were determined when the predator fed on protonymph and larva, respectively. The highest daily mean number of eggs (1.10±0.10) laid by A. swirskii was obtained at 120 egg density. No significant difference was determined in egg production of the predatory mite among different life stages within the same prey density except 10 prey density. In addition, there was also no difference among prey densities within the same biological stage, except egg stage. According to the results, A. swirskii may not be directly recommended for the biological control of T. evansi on tomato. However, when its inundative release is considered, it may help and improve the success of biological control of T. evansi, especially at early stages of infestations.

Evaluation of Phytogenic Feed Additive on Egg Production, Egg Quality and Feed Intake in Layer Chicken

The commercial layer production in chicken farms has usually been exposed to wide range of stress stimulants, which adversely affect the feed intake and body weight that in-turn depress the egg production and quality. Hence, it’s a major area of concern to reduce the stress and increase the production benefiting the farmer and health of the bird. The present study was designed to evaluate the impact of phytogenic feed additive (PGC) on egg production, egg quality and feed intake in layer chicken. A total of 320 birds of age 65 weeks of BV300 layers were randomly assigned to 2 groups (Control and PGC groups) with 10 replicates comprising 16 birds each (n = 160). The control group was provided with standard commercial feed as recommended by NRC specifications. In PGC group PhytoceeTM was supplemented at 200 g/ton with standard commercial feed. The study period was 6 weeks (65 weeks to 70 weeks) and data was collected on 7 days interval. The data on egg production, feed intake and egg quality parameters (egg weight and shell parameters) were collected during the study. The group fed with PGC had showed numerical improvement in egg production and decreased egg defects during the study period when compared to control group. The feed intake was not much altered in both the groups. The egg density, egg strength, shell weight, shell thickness and shell percentage were numerically improved in PGC supplemented group when compared with control. The supplementation of PGC had considerably improved the egg quality and production parameters in layer birds by helping them in reducing the harmful effects of stress.

Density Of Eggs and Larvae of Aedes Spp and the Characteristics of their Larvae Habitat in Endemic Dengue Area of Ternate City

Introduction: Dengue Fever (DF) is a disease spread by Aedes spp. caused by dengue virus infection. The study aimed to identify the density of Aedes spp eggs and larvas stages and the characteristics of their habitat in dengue-endemic areas in Ternate City in September-December 2021. Methods: the research was conducted in four dengue-endemic villages in Ternate City, namely Sangaji, Maliaro, Bastiong Karance, and Bastiong Talangame village. In 80 households, egg density was determined by placing 2 ovitraps in each house, one inside and one outside the house. After a week, the filter paper which is a medium mosquito to lay their eggs in the ovitrap was collected, and the ovitrap index value was calculated. The value of the House Index (HI), Container Index (CI), and Breuteu Index (BI) was used to calculate the larval density. The type and materials of the containers were used to assess the parameters of the larval environment. Results: The ovitrap index value in the four villages was categorized as moderate level 3 (27.50% -36.25%). The highest larval density was found in Sangaji Village (HI = 81%), while the lowest was in Bastion Talangame Village (HI = 70%). The highest CI and BI values were found in Bastiong Karance Village (CI=51.5% and BI=190%), and the lowest was in Maliaro Village (CI=37.5% and BI=128%). Density figures in all endemic villages have a high larval density with a value of 8. Conclusion: There was no significant difference (p&gt;0.05) between the types and the materials of containers in each village in Dengue endemic areas. The high density of the egg and larval stage and the information characteristic of habitat Aedes spp. could be considered as basic information for dengue vector control in Ternate City.

Analysis of a hypersaline drought-prone estuary reveals low density and diversity of fish eggs and larvae

We analyzed fish eggs and larvae in an estuary under severe drought conditions. We detected an inverse salinity gradient, with values increasing from the mouth to the upper estuary. Egg densities decreased from the estuarine mouth to the upstream areas following the salinity increase for all three mesh net sizes. This pattern was also found for the density of larvae, which decreased in estuarine regions with hypersalinity (38 to 62). The low diversity constituted only nine fish species, which were classified as anadromous (Anchoa hepsetus), estuarine and marine (Bathygobius soporator, Hippocampus reidi, Eucinostomus sp., and Diapterus auratus), marine estuarine-opportunist (Caranx latus and Bardiella rochus), and marine stragglers (Echeneis naucrates and Haemulon sp.). In addition, we observed an oversimplification of the assemblage to include stress-tolerant estuarine and marine species. Our baseline results suggest that this hypersaline estuarine ecosystem has lower densities and diversity than a healthy mangrove system.

Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments

Al-Issa, Z., M.N. Salti, M. Nabahan and A. Khalifa. 2023. Identification of Resistance Traits Against Whiteflies, Bemisia tabaci in Certified Varieties and Promising Strains in Field and Semi-Field Experiments. Arab Journal of Plant Protection, 41(2): 173-182. https://doi.org/10.22268/AJPP-41.2.173182 Plants have developed defense systems to cope with pests’ challenge, especially insects to reduce their damage. In this study, some resistance traits in 30 cotton (Gossypium hirsutum) genotypes against cotton’s whitefly, Bemisia tabaci (Genn.) were evaluated through semifield experiments, where antixenosis of certified varieties and promising strains to the insect where studied by designing adhesive cage placed on leaves of the plant third upper, insect development from egg to adult were regularly observed and rates of development and survival, lifespan, sex ratio, and total emergence of adults were monitored. Preference test was conducted through recording numbers of different insect stages in 1cm2 area. Field experiments were carried out by planting cotton genotype for two successive seasons (2018, 2019). Insect density was evaluated by measuring whiteflies density every 15 days until the end of the growing season. During the 2020 season, trichome density in 1cm2 area was determined and their length and diameter were also determined at the 8 th node of cotton genotypes. The results showed that no significant differences among cotton genotype in relation to insect survival rate, lifespan, sex ratio, and emergence rate of adult. This study revealed that there were significant differences in trichome density in 1 cm2 of leaf area ranged between 86.33 to 160.7/cm2 . The correlation was significantly negative between egg and trichome density (R= -0.984). However, no significant correlation between length and diameter of trichome with nymph and egg density. The egg density varied from 32 to 54 egg/cm2 , whereas nymph’s density varied between 3.8 to 6.1 181 Arab J. Pl. Prot. Vol. 41, No. 2 (2023) nymphs/cm2 , and the variety Raqqa 5 had the highest density of whitefly nymphs and eggs during the two seasons. Whiteflies density peak was around mid-September and started to decline until mid-October. The results obtained suggested that there is a role for trichome density in resistance to whiteflies and there aren’t antixenosis between studied cotton’s genotypes. There is a need to investigate cotton genotypes from different cotton species such as G. arboreum, G. barbadens, G. thuberi for the presence of insect resistance traits. Incorporation of such resistance in cotton cultivars is a key for sustainable pest management. Keywords: cotton’s whiteflies, egg number, nymph number, resistance traits, preference, trichome

The Nematicidal Activity of Moringa Oleifera Leaves Extract Against Gastro-Intestinal Strongyles of Small Goats

Introduction: Gastrointestinal nematodes have a deleterious effect on animal health and production. In search of alternative to synthetic anthelminthics in the control of strongylosis among small ruminants, this study was conducted to evaluate the in situ adulticidal properties of Moringa oleifera on gastro-intestinal strongyles of goats. Methods: Twenty (20) goats naturally infested with mixed gastrointestinal nematodes were distributed into 5 groups (n=4): a negative control group receiving Tween 80 at 2.8%, a positive control group treated with Albendazole at 5 mg/kg and tested groups treated with doses of extract (125, 250 and 500 mg/kg). In situ anthelminthic activity was assessed through determination of the faecal eggs count reduction, total worm count reduction, variation of packed cell volume (PCV) and body weight after treatment. Results: Five species of nematodes were identified among experimental animals, with Strongyloides papillorus as the most prevalent (93.8%) followed by Haemonchus contortus (87.5%). At dose of 500 mg/kg, ethanolic extract of M. oleifera registered 76.4 % and 69.8 % eggs density reduction of gastro-intestinal strongyles eggs and parasitic load nineteen days post-treatment respectively while Albendazole induced 100 % reduction of these same parameters at the dose of 5 mg/kg. Moreover, the extract did not significantly affect PCV nor body weight of experimental goats. Conclusion: This study validates scientifically the use of alcoholic leaves extract of M. oleifera in the treatment of gastro-intestinal strongyles. The standardization of this extract is however necessary for his use as a sustainable tool for controlling strongylosis in small ruminants.