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The obscure mealybug, Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae), is an important polyphagous, cosmopolitan insect pest of fruit crops, including apples, pears and grapes. The mealybug negatively affects fruit production both in South Africa and globally by feeding on phloem sap, excreting large amounts of sugar and water as a carbohydrate-rich sugary substance, known as honeydew, onto the leaves and fruit. Honeydew causes severe secondary damage, as it promotes the growth of sooty mould, which decreases the amount of photosynthesis, thus affecting the development of the host plant. Fruit consignments with fruits stained with sooty mould or suspected of containing live or dead mealybugs are rejected when exported, due to the strict phytosanitary standards. Managing mealybugs in agroecosystems is difficult, due to their small body size and cryptic nature. Currently, control relies on the use of chemicals and, to some extent, on biological control. However, using such methods has proven to be ineffective in the management of P. viburni. Entomopathogens, such as entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs), have been used across agricultural production areas to control a wide range of agricultural pest insects. The current review provides an overview of the biology and control of P. viburni, with special reference to biological control using EPF and EPNs in South African orchards, in an integrated pest management system.
Laboratory studies were carried out to determine the efficacy of ozone (O3) technology as a management tool against larvae of Ephestia cautella, Plodia interpunctella, Trogoderma granarium and Tribolium castaneum. In addition, some biochemical changes and ultrastructural alterations in the above-mentioned larvae were studied. Larval mortality of the four species increased as concentration and exposure periods increased. Complete mortality was observed after 8 h. The LT50–99 values of ozone gas against the larvae decreased as concentration increased. Caterpillars were more sensitive to O3 than grubs. Data also showed that the effective effect of ozonation towards the four larval species indicated that not all insects had the same sensitivity to ozone gas. There was a significant increase in super oxide dismutase (SOD) levels in E. cautella and T. castaneum subjected to LT50 of ozone. Moreover, there was a significant decrease in nitric oxide concentration in both larvae after LT50 of ozone exposure. Ozone-treated larvae suffered from heterogeneous muscles with degenerated nuclei. The neurosecretory cells were found with accumulated neurosecretory materials. The neuropil glia appeared loose and vacuolated. Antenna appeared with loose sinus, and there were no artery nor trachea found. The mushroom body of brain calyces appeared with distributed Kenyon cells. The cuticular layer was degenerated. The tracheae were collapsed. Thus, ozone gas may be used as a clean and safe agent to fight these pests.
The current study evaluated the effect of electromagnetic radiation on the stomach cells of honey bee foragers. Normal cells are distinguished by different heights with well-developed muscular layers and an internal plasma membrane. During our study we used a mobile phone (Samsung F400) with the provider Vodafone, Egypt and a carrier frequency range of 900–1900 MHz. Bee workers were captured while returning from the field to the hive (about 23 days old). When honey bee foragers were exposed to mobile phone radiation for 20 min, the stomach cells were completely decayed. With regard to stomach cells which were exposed for 10 min, some parts of the cells were completely lysed, appeared as a thin tubular-like layer, or as compact mass, and the internal plasma membranes were not clear. Also, the chemical element composition of the cells exposed to 10 min of mobile phone radiation was affected as follows: Mg, Ca, Zn and Fe elements were significantly increased, while sulphate elements were significantly decreased. The current study demonstrated that mobile phone radiation is harmful to honey bee stomach cells, and we recommend limiting the use of mobile phones near hives.
The South American tomato pinworm, Tuta absoluta (Meyrick 1917) (Lepidoptera: Gelechiidae), is an invasive pest native to South America. Outside of its native range, it was first detected in Spain in 2006 and then rapidly spread to most tomato-growing regions in Central America, Europe, Africa and Asia where the species has become a major threat to tomato production. To implement appropriate policy and surveillance practices, to limit new introductions and spread, and inherent economic losses, better knowledge of its invasion pathways is required. To this end, a large sampling of T. absoluta was performed in native and invaded areas including European and for the first time many African countries. Samples were analysed using a mitochondrial marker (mtCOI) and a phylogenetic approach. Despite extensive sampling and sequencing efforts, an overall lack of genetic variation among the tested specimens (140) was observed. This striking finding may result from a combination of factors and phenomena such as extensive gene flow, severe bottlenecks, reproductive system and human activities, and will be discussed in the framework of biological invasion and pest management.
Pauesia antennata Mukerji is a specific parasitoid of the brown peach aphid Pterochloroides persicae Cholodkovsky which causes severe damage on almond and peach in Tunisia. To control this pest, P. antennata was collected from Iran, introduced to Tunisia in 2011 and some of their biological parameters were studied in laboratory conditions. Therefore, in orchard, aphid population and sites/zones of Tunisia and aphid behaviour impact on the parasitoid have not been studied. Morphometric measurements, molecular analysis of P. persicae specimens collected from two Tunisian sites [(Akouda-Sousse (Site 1), Sfax (Site 2)] were studied and compared and aphid behaviour versus P. antennata was followed. Results demonstrated a significant difference of four morphological characters (body length, body width, total antennal length, hind femora length). Molecular analysis showed two haplotypes corresponding to the sites. For biological analysis, larval longevities were 14.3 ± 1.52 and 12.6 ± 2.08 days for Site 1 and Site 2, respectively. Fecundities were 20.2 ± 13.57 and 12.3 ± 11.06 larvae/day corresponding to Sites 1 and 2, respectively. A relationship between P. persicae specimens and behaviour versus P. antennata were explained.
Invasion of crops by stemborers previously known in natural vegetation only requires close monitoring for early detection of stemborer exchange between the habitats. This in turn demands up-to-date knowledge about the diversity of stemborers in natural habitats. The current list of known stemborers in South Africa includes 49 species associated with 65 wild host plant. The Eastern Cape and KwaZulu-Natal biogeographic regions received little coverage in earlier studies. This study sought to fill this knowledge gap. We conducted surveys from 14 November 2014 to 18 March 2015 in the Eastern Cape and KwaZulu-Natal biogeographic regions. Potential host plants in families Poaceae, Cyperaceae, and Typhaceae were dissected in the field, stemborer life stages collected, reared on artificial diet, and identified to the lowest possible taxonomic level. Thirty-three species belonging to Crambidae, Noctuidae, Phycitidae, Pyralidae and Tortricidae were recovered from 27 host plant species. Twenty-four species were recorded in Eastern Cape and 28 species in KwaZulu-Natal. The Chao 1 asymptotic species richness estimator predicted 3 and 5 more species for the biogeographic regions indicating an equitably complete species inventory of the study area. Fifteen species collected in this study are part of the existing inventory, and 19 are first records on the various host plants. The new records expand the list of stemborer species in South Africa from 49 to 68. The main factors influencing diversity were endemism, the number and disproportionate abundance of common and rare species.
Global demand for high-quality animal protein is expected to increase astronomically by 57 % come 2050 and meeting this demand will be quite challenging. However, insect as food is a safe alternative considering the fact that most insects have dietary quality. This is due to their rich protein content which is comparable with conventional animal sources of protein. In Nigeria, the pest Analeptes trifasciata is one of the edible insects, which is consumed among others such as grasshoppers, locusts, termites, palm weevils and crickets in most rural communities. The nutritive composition of adult male and female cashew stem girdler beetles (A. trifasciata) were analysed by proximate analysis to determine the crude protein, crude fibre, ash content, ether extract, dry matter and moisture content. Also minerals such as calcium, magnesium, sodium, phosphorus, iron, cadmium, zinc and manganese and vitamin (A, B, C, D, E and K) contents were analysed using standard methods. Student t-test was used for the statistical analysis. The crude protein (39.63 ± 0.04 %), crude fibre (0.43 ± 0.01 %) and water content (53.03 ± 0.01 %) of males were significantly higher than that of females. Females recorded higher values of dry matter compared to males. Males recorded significantly higher vitamin content than females, for vitamin B1 (0.216 ± 0.001 mg/100 g), vitamin B2 (0.058 ± 0.001 mg/100 g), vitamin B12 (1.37 ± 0.01 mg/100 g) and vitamin C (0.89 ± 0.01 mg/100 g). Females recorded significantly higher (P < 0.05) contents of vitamins A (725.3 ± 0.12 µg/100 g), D (189.5 ± 0.12 mg/100 g), E (266.7 ± 0.12 mg/100 g) and K (31.8 ± 0.12 mg/100 g). Females had higher mineral contents of Ca2+, Na+, P+, Fe2+ and Mn–. The results show that A. trifasciata has high protein content making the beetle a cheap and excellent source of protein. The micronutrients are in favourable proportions and the beetle can be explored as a strategy for tackling nutritional deficiencies.
Virgin queens of the honey bee Apis mellifera L. were assessed following feeding in fourth larval instar with a sublethal dose of bacterium Paenibacillus larvae larvae (LD20 = 1.07 × 102 colony forming units (CFU)/queen), the causative agent of American foulbrood disease (AFB). The extraction of ovary proteins showed a highly significant increase for treated queens. The bacterium P. l. larvae was detected by conventional PCR-technique within treated queens ovaries with molecular size of 550 bp. Vitellogenin gene has been expressed in healthy and treated queens using RT-PCR technique, up-regulation took place in treated queens, vitellogenin was found with a high level of gene expression (∼20-fold). Finally, this study could contribute to initial efforts to help attempts to breed honey bee queens that are resistant to the pathogen.
High trait variability among insects reflects a combination of intra- and inter-phenotype variations. Our aim was to assess if the trait distribution of body measurements can be more significantly influenced by sex (intraspecific variance) or by species (interspecific variance). To achieve this, we collected in Namibia tettigoniids belonging to two congeneric species of armoured ground crickets: Acanthoplus discoidalis (a significant pest in African croplands) and the long-legged Acanthoplus longipes. We measured in the field the total body length, the maximal pronotal width and length, and the femur and tibia lengths of the hind legs in 106 adults. We also derived the body mass from length and width values of the sampled specimens. No significant differences emerged in the two species by sex. A discriminant analysis clearly shows that at species level the locomotory traits as captured by tibia and femur lengths and the size traits as captured by body and pronotal lengths account for 99 % of the total variance and clearly separate this pest from its congeneric species. In essence, it is not primarily the body size that differentiates the two species, but rather the pronotum and hind leg larger sizes of A. longipes. Different eco-ethological requirements, like the peculiarity of the calling song and the movements within the vegetation (and the consequently needed energy), independently force these functional traits.
The gradual increase in kernel (nut) size as the macadamia seed develops, appears to play a role in the decline of kernel susceptibility to feeding by insects of the suborder Heteroptera. In some cultivars the kernel becomes resistant to feeding before others due to differences in husk and shell thickness (e.g. feeding by Nezara spp.), but species with a long proboscis (e.g. Bathycoelia spp.) could still feed on the kernel after maximum fruit size was reached. The thickness of the husk and shell, and not the hardness of the shell, was the limiting factor in kernel feeding. Bathycoelia distincta Distant (Pentatomidae) and Pseudotheraptus wayi Brown (Coreidae) were the most damaging heteropteran species with respect to the size of the kernel lesions caused. A single feeding incident during early fruit development could cause large necrotic lesions, which totally malformed the kernel. Farnya sp. and Nezara sp. caused only small shallow lesions. During the fruit maturation period, only B. distincta was able to damage the kernel significantly due to its long proboscis. The extent of fruit damage was dependent on the stage of fruit development and the species concerned. A tolerance index was developed to express the relative tolerance of macadamia cultivars to the damage caused by kernel-feeding Pentatomidae at the later stages of fruit development. Parameters for the index were the number of pentatomids attacking macadamia, their proboscis length and the combined thickness of the husk and shell of the fruit.
High and low developmental temperatures can induce physiological stress in insects, including oxidative stress that needs to be eliminated by increased antioxidant activity. Alien invasive ladybird Harmonia axyridis (Coleoptera: Coccinellidae) possesses high toxicity and immunity defence abilities, but it is sensitive to temperatures above 35 °C. We quantified the activity of antioxidative enzymes in the adult ladybirds that spent the pupal stage at moderate, low and high temperatures that can cause a physiological stress. Total antioxidant (TAO) and Glutathione S-Transferase (GST) activities of ladybirds H. axyridis were highest in extracts from freshly emerged adults developed at low temperature (17 °C), moderate in beetles from medium temperature (26 °C) and lowest in beetles from high temperature (35 °C). Superoxide dismutase (SOD) activity was highest at the medium temperature. After one day of adult life at the medium temperature, antioxidative activities of individuals originated from the three temperatures became similar: low for TAO and GST and high for SOD. Metabolic needs of the beetle organism during emerging from pupa seem to be stronger than reactions to diverse temperatures.
Maize (Zea mays) and beans (Phaseolus species) are staple food, feed and sources of income for millions of people in developing countries and most especially for the people of the North West Region (NWR) of Cameroon. Production and storage of these grains is greatly hampered by inappropriate storage practices and pest infestation. This study determined the storage practices and insect pests associated with these grains in the NWR of Cameroon. A structured questionnaire designed to document the indigenous methods of storing maize and beans against post-harvest insect pests with particular emphasis on plants and plant-derived materials used was administered to 29 farmers selected from Babungo, Kom and Oku villages in the NWR of Cameroon. Samples of maize and beans were also collected from the stores of respondents to collect and identify the insect species. The 29 respondents used more than one method to protect their grains against damage by insects in storage. The different methods implored were conventional methods, local plants and wood ash with independent counts (percentages) of 18 (62.1 %), 18 (62.1 %) and 7 (24.1 %), respectively. Sitophilus zeamais, Tribolium casterneum, T. confusum and Brachymeria spp. were recorded in maize while only Acanthoscelides obtectus was recorded in beans. There were no significant differences in the number of insects recorded across the study sites. Therefore, post-harvest insect pests are a common problem in the NWR of Cameroon. Farmers within this region also use different methods of post-harvest storage practices to combat these pests. Integrated methods of post-harvest management should receive high priority to prevent damage and losses incurred. Management practices should focus on further developing plants used in post-harvest storage. There is equally a strong need for training farmers on aspects of post-harvest storage practices and management in the NWR of Cameroon.
The bud-galling midge, Dasineura strobila Dorchin (Diptera: Cecidomyiidae), is one of two biological control agents that have been introduced into South Africa to control the invasive tree, Australian myrtle, Leptospemum laevigatum (Gaertn.) F.Muell. (Myrtaceae). Whilst both agents are established and widespread, L. laevigatum continues to grow vigorously and spread within its range. Earlier studies reported decreasing populations and reasonably high levels of mortality of the midge; however, the role of this mortality in regulating D. strobila populations was not proven. A re-assessment of the mortality factors on D. strobila confirmed the continued presence of both parasitoids and a predatory mite, accounting for only 5 % and 4.9 % mortality respectively over a two-year period. Whilst outbreaks of predatory mites could occur, mortality is not believed to be a driving force in regulating D. strobila populations. Although further studies are required to clarify the situation, it is suggested that despite the presence, and relative abundance of the midge, its impact as a biocontrol agent for Australian myrtle, remains negligible.
Many human activities have an impact on the fauna and flora of the South African Grassland Biome, including agriculture, fire and urbanisation. Disturbances in grassland habitats often result in Hyparrhenia hirta, a native pioneer grass species, establishing dense stands. Here the assemblage composition, species richness and abundance of spiders associated with H. hirta tussocks was investigated at three grassland sites (annually burnt, suburban local road traffic and undisturbed control) in the central Free State Province of South Africa during winter 2015 and 2016. Further, inter-annual differences during a period of intense drought were evaluated. An increase in spider species richness, abundance and different assemblage composition with increased tussock height and basal circumference was expected, and we predicted these effects would differ between land use types. Overall, Tibellus spp. immatures (Philodromidae) and Poachelas striatus Haddad & Lyle, 2008 (Trachelidae) were the most abundant spider species, while Philodromidae and Gnaphosidae were the most abundant spider families at all three sites during both years. The most species-rich families were Gnaphosidae, Salticidae and Thomisidae. Over the two-year sampling period there was a significant decline in overall spider abundance (58.09 %) and species richness (28.17 %), which could be explained by the cumulative effects of a severe drought experienced in central South Africa during 2015 and 2016. Species richness and assemblage composition were influenced by tussock basal circumference and disturbance effects, but not by tussock height. Several species were associated with the control site, while certain diversity metrics of the burnt and road verge sites were more stable, pointing to the importance of primary productivity in the former and water in the latter, for spider diversity. Trade-offs related to disturbance need to be carefully considered when developing management strategies for biodiversity.
Stingless bees are important resources for pollination of crops, production of medicinal honey and other products. However, throughout the developing countries in Africa, meliponiculture has received less attention in beekeeping development programmes. Here, the current situation of stingless beekeeping in Uganda is assessed. First, stingless bee species utilised for their products were collected and identified. Thereafter, the economic benefits derived from stingless beekeeping in the Western Highlands agro-ecological zones of Uganda with anecdotal reports of meliponiculture were analysed. The findings reveal that stingless beekeeping is in its early stages of development in Uganda. Four stingless bee species were identified: Meliponula bocandei, Meliponula nebulata, Meliponula ferruginea and Plebeina hildebrandtii that are currently used for honey and propolis. These stingless bee species can be selected for domestication, targeting different products such as honey, propolis and pollen to make meliponiculture more profitable. Indigenous knowledge of beekeepers that can assist in locating wild stingless bee nests for domestication was documented as it is essential for the preservation of this practice. In order to transform the stingless beekeeping industry in Uganda, training needs such as hive making, colony management, product harvesting and processing will have to be addressed.
Pomegranates are attacked by invasive fruit flies of the family Drosophilidae including the African fig fly, Zaprionus indianus. This species is reported for the first time from North-East Algeria reared from pomegranate fruits from two commercial pomegranate orchards. This vinegar fly is an opportunist that uses both fallen fruits and damaged fruits still on the pomegranate tree as breeding substrates. We report percent infestation of fruit of Z. indianus and of several other pomegranate insect pests.
The objectives of this study were the specific taxonomic confirmation of the main olive seed wasp (OSW) attacking commercial olives in the Western Cape, to investigate monitoring methods and seasonal occurrence of OSW, to determine the potential economic damage of infestations, and to ascertain the geographic distribution of OSW in the regions where olives are cultivated in the Western Cape. Morphological and molecular methods were used to identify all the species obtained from cultivated olives at two trial sites near Stellenbosch and Agter-Paarl. Eupelmus spermophilus Silvestri (Hymenoptera: Chalcidoidea) was by far the most frequent and widespread olive seed wasp. Monitoring with yellow sticky traps over three seasons indicated OSW presence in orchards when olives were small enough for OSW to oviposit in, but traps were not reliable indicators of OSW infestation levels. Prematurely dropped olives, collected from February until harvest over three seasons, and olives picked at harvest were examined for OSW infestation. Total yield for each data tree was recorded at harvest, and yield loss due to OSW infestation calculated. Economically significant yield losses occurred sporadically. Fruits collected from both cultivated and wild olive trees indicated that OSW occurs in most olive-growing regions of the Western Cape. OSW does not pose a significant threat to the local olive industry as a whole and cannot be considered a key pest of olives, but during some seasons it can affect production yields where wild olive trees are located near commercial olive groves.
The lepidopteran leaf-mining larvae of Holocacista capensis were recorded on the outskirts of Paarl (Western Cape), South Africa, in 2012 for the first time. Thought to have local origins, the moth has been recorded on many grape varieties in South Africa since. In order to develop appropriate management strategies, aimed at maintaining effective control of the pest in commercial vineyards, various aspects of the pests′ ecology must be known. The current study provided morphological characteristics associated with wing and abdominal colouration, which can be used to discern between male and female moths using a stereo microscope. The seasonal cycle of larvae and adults throughout a grapevine growing season was established. The leaf miner was detected in the three grape areas surveyed (Berg River, Hex River and Olifants River). Areas in the grape producing regions of the Western Cape that are heavily impacted by the leaf miner include Paarl, Riebeeck Kasteel, Tulbagh, Piketberg and Wellington. Moth and larval abundances were observed to reach considerably high numbers in February. Live larval abundances decreased from the middle of March, whilst adult abundances were only seen to drop in early April. This study aimed to assist towards the development of appropriate management strategies against the pest.
Psylloids cause severe damages to their host plants and transmit serious plant diseases for several crops in different parts of the world. The species composition and geographical distribution of psylloids in Egypt were assessed. The abundance of Heterotrioza chenopodii (Reuter, 1876) on various host plants in different ecological zones and their monthly abundance in Wadi El-Natroun were monitored throughout three successive seasons. We used a sweep net and a mechanical aspirator to survey populations of Psylloidea species from 2014 to 2017. Twenty-six psylloid species belong to four families were recorded from six geographical zones. H. chenopodii was the most widely distributed psylloid species in Egypt. The total number of species collected per zone ranged from a minimum of two at Fayoum Basin (FB) to a maximum of 15 at Lower Nile Valley and Delta (LNVD). The highest number of psylloid species were sampled from the host plant Tamarix sp. (6 species) followed by Zygophyllum sp. (5 species). The negative binomial regression analysis showed that the abundance of H. chenopodii is more dependent on host plants (χ2 = 61.5, P < 0.001) than ecological zones (χ2 = 11.9, P = 0.018). Density of H. chenopodii in Wadi El-Natroun showed a bimodal seasonal pattern with two peaks of adult abundance: spring (April) and late autumn (December). Moreover, we recorded a drop in the psylloid densities during hot (summer) and cold (winter) seasons. Additional ecological and taxonomic studies on Psylloidea are needed to conduct integrated pest management against species with economic and pharmaceutical interests.
Thrips is a harmful cosmopolitan polyphagous pest with marked serious and adverse effects on over 200 host plants, it infests tomatoes, sucking and destroying its seedlings. This study was carried out in a Rogina tomato hybrid field in three governorates, El-Beheira, El-Faiyum and El-Sharqia, in Egypt. In order to evaluate the efficacy of five predatory mites (Mesostigmata: Phytoseiidae) namely; Typhlodrompis swirskii, Phytoseiulus persimilis, Neoseiulus cucumeris, Typhlodromus nigavi and Neoseiulus californicus as well as the recommended combination (abamectin + Egyxide oil) as standard insecticide (1 ml + 2.5 ml/l) separately or combined with each other against Thrips tabaci nymphs and adults. The current study indicated that the single treatment with T. swirskii and N. cucumeris as well as the recommended combination (abamectin + Egyxide oil) were the most efficient as a bioagent control against T. tabaci in tomato plants in all three governorates, followed by T. nigavi, whereas P. persimilis and N. californicus has no role as a biocontrol agent for T. tabaci in single treatment compared with control. Moreover, alternately using predatory T. swirskii in combination with other predators (N. cucumeris, T. nigavi and N. californicus) showed significant reductions (95.8–99.95 %) in T. tabaci populations without any incompatibility or competition between each other compared with control in all three governorates (LSD: 3.46, indicated that there is no significant difference between treatments in all governorates). In general, the reduction effect of all treatments in El-Faiyum was decreased more than the other two governorates. This study demonstrated that T. tabaci in tomato can be reduced by using T. swirskii and N. cucumeris singly or alternately mixing with other predators mentioned above. In the light of these results, the T. swirskii and N. cucumeris singly or alternately should be considered when deciding on the timing of abamectin applications within IPM strategies.
Stored-product pests attack cereal grains and legume seeds post-harvest. They not only damage the grain but also decrease its weight and quality. Therefore, the aim of the present study was to investigate the bioactivity of resin powders extracted from Pistacia lentiscus L. bark, Boswellia carterii birdwood bark, and Elettaria cardamomum seeds against two of the most important stored-product pests, Sitophilus granarius (L.) and Tribolium confusum Jacquelin du Val. We used three bioassay methods, repellent effect, reduction of progeny, and grain weight loss and investigated the effects of the powders on the life cycles of the insects. Wheat grains were mixed with the three botanical powders separately, at different concentrations (3, 5, 7, and 10 % w/w). Sitophilus granarius and T. confusum were fed these mixtures. Repellent activity was examined after 2, 4, 8, 12, and 24 h. The E. cardamomum powder displayed the maximum repellent activity (100 %) against both S. granarius and T. confusum after 24 h at 3 % concentration. The P. lentiscus powder reached maximum repellent activity (80 %) against S. granarius and T. confusum at 7 % concentration after 12 h and 24 h, respectively. The B. carterii powder achieved maximum repellent activity against S. granarius and T. confusum (73.3 % and 86.7 %) at 10 % concentration after 24 h and 12 h, respectively. No progeny was produced in grains treated with 3 % P. lentiscus powder, 7 % E. cardamomum powder, or 7 % B. carterii powder. Thus, protection against both beetles started from 3 % concentration when P. lentiscus powder was used and from 7 % and 10 % (against S. granarius and T. confusum, respectively) when E. cardamomum powder was used. A 7 % B. carterii concentration completely saved the grains from S. granarius damage, and a 10 % concentration offered 99.5 % protection against T. confusum. However, all tested powders significantly affected all the studied parameters (life cycle and grain weight loss). The results show that the three botanical powders provide high repellent activity against S. granarius and T. confusum, which might be useful in protecting stored grains from these insects.
We describe the queen caste of the Arabian endemic species Tapinoma wilsoni Sharaf & Aldawood, 2012 from the type locality (Dhi Ayn Archaeological Village) located in the southwestern mountains of the Kingdom of Saudi Arabia. We present the first illustrated key to the Arabian TapinomaFoerster, 1850 based on the queen castes. Three species are recognised from the Arabian Peninsula,T. melanocephalum (Fabricius, 1793), T. simrothi Krausse, 1911 and T. wilsoni Sharaf & Aldawood, 2012.
Mango production and trade is a major source of employment, food and income in Sub Saharan Africa (SSA). Most of its production in SSA is under smallholder farming with a few commercial farms undertaking production. Fruits are traded both locally and some exported, with improved exotic varieties being preferred by consumers. However, mango export which is more lucrative to most exporters in terms of foreign currency exchange earnings, is currently faced with serious quarantine restrictions because of the invasive fruit fly, Bactrocera dorsalis. Since its invasion in Africa, yield losses of up to 100 % have been recorded. In addition, loss of export due to restrictions has resulted in loss of potential revenue from lucrative markets such as the European Union. This study aimed at determining postharvest disinfestation parameters for B. dorsalis using hot-water treatments. To attain this, the development of B. dorsalis in the mango cultivar Tommy Atkins was determined. This information was used to treat different immature life stages at 46.1 °C for 12, 24, 36, 48, 60 and 72 min. Mortality of the different life stages over the different duration of treatments was determined. There was an increase in mortality with increasing duration of treatment for all life stages. The egg and first instar life stages were the most heat susceptible stages followed by the second instar larvae. The third instar was the most heat tolerant life stage evaluated and required treatment at 46.1 °C for 86.7 min (95 % CL (77.830–99.880)) to achieve 100 % mortality. Validation experiments at this temperature and treatment duration resulted in no survivors from the 41 542 third instar larvae treated in Tommy Atkins weighing 500–700 g. These results provide an effective treatment protocol which can be adopted by exporters in re-accessing currently inaccessible lucrative export markets in the U.S.A. and Europe.
In Africa, there are two well-known subspecies of the desert locust; the Sahara subspecies, Schistocerca gregaria gregaria (Forskål, 1775), and the southern African subspecies, Schistocerca gregaria flaviventris (Burmeister). The northern locust, S. g. gregaria, extends across the Sahara desert to western Asia. The invasion area of the southern subspecies, S. g. flaviventris, extends to Namibia, Angola, South Africa, Ascension Islands and Botswana. Four different locust populations were selected, three populations for the northern S. g. gregaria (f, e, r) from different localities and one population for the southern S. g. flaviventris (s). Three characters were selected, the length of the forewing (E), the length of the posterior femur (F), and the widest part of the head capsule (C). Two ratios (E/F, F/C) were also calculated and compared for the different populations. The univariate analysis technique using the ANOVA test was performed for the four locust populations. The means of the different measured characters and the two ratios indicated significant differences between the southern population and the other three northern populations. The mean values of E, F, C, and E/F ratio were lower for the southern population compared to the three northern populations. Multivariate analysis of variance indicated that the four locust populations were highly significantly different (P < 0.0001). Standardised canonical coefficients for the three characters and the two ratios were given. The Mahalanobis distance (D2) between the centroids of the different populations for the three measured characters and the two ratios were significantly different (P < 0.0001). The distances recorded between the southern and the three northern populations were higher than the distances between the three northern populations. The results indicated that the southern males and females are more morphologically closer to each other than to either sex of the northern locusts. Also, the two sexes of the northern populations are more or less similar in their morphological features than the southern locust population. We may suggest that the southern population may categorise an evolutionary dichotomy that has arisen on the African continent and may separate the two locust populations into two distinct species.
Culex pipiens (L.) has a wide distribution worldwide and is the main vector of many diseases. Mass rearing of all target vector mosquito species is frequently required for public health research and vector control. Vector mosquito species are anautogenous, they need vertebrate blood for egg production. Therefore, female blood feeding is essential for colonisation. Various artificial feeding methods have been developed over the years but they lack consistency. Thus, we have developed an artificial feeding technique for rearing and infection experiments as an attempt to establish a practical guide for vector research. Culex mosquitoes were fed directly and artificially; four blood sources (human, cattle, rat and pigeon) and three different membranes (chick, sausage casing and Parafilm-M®) were assessed based on feeding rate, fecundity, oviposition, egg hatchability and infectivity. The chick membrane was considerably more efficient than sausage casing and Parafilm-M. Using the chick membrane with different blood sources, feeding rates (FR) were 89.60 %, 86.20 %, 61.60 %, 50.40 % for human, cattle, rat and pigeon blood, respectively. There was statistically no significant difference in FR between cattle and human blood. Hepatitis C virus infection was carried out successfully using the artificial feeding technique with chick membrane. RT-PCR readings proved that Culex pipiens can harbour this virus for five days through the midgut region. Cattle blood with chick membrane in mosquito rearing is a good substitute for human blood and live feeding for its availability and cost effectiveness. Overall, this method could be recommended in mosquito experimental infection, vectorial capacity and pathogen interactions studies.
Culex pipiens (Cx. pipiens) or common house mosquito is the most widely distributed species worldwide, including Saudi Arabia. The current study examined morphological, histological, and ultrastructural features of midgut epithelium of fourth instar larvae of Cx. pipiens. Findings provide a basis for research on insecticide resistance and mosquito control. The morphological, histological and ultrastructural studies used both light and transmission electron microscopy. Morphologically, the external features of the body of the larva show three main regions, head, thorax and abdomen, with 10 externally visible segments. The digestive tract includes foregut, midgut and hindgut. Histologically, the midgut is lined by a single layer of cuboidal or low columnar epithelial cells associated with intercalated regenerative cells scattered. All cells rest on a thick basement membrane. Ultrastructurally, cuboidal to low columnar cells of the midgut of fourth larval instar shows absorptive cells with apically well-developed striated borders of microvilli and large rounded central nuclei, resting on a thick basement membrane. Thin intercalated regenerative cells are scattered among epithelial cells. The apical cytoplasm epithelial cells display numerous mitochondria, rough endoplasmic reticulum, vacuoles and secretory vesicles. A distinct peritrophic membrane is seen that acts as a protective barrier between haemolymph, midgut cells and food contents. The current study concludes that Cx. pipiens fourth instar larva midgut lined by a single layer of broad cuboidal to low columnar epithelial cells with large spherical nuclei, numerous mitochondria, lysosomes and secretory vesicles, and apical regions with well-developed brush borders of microvilli. They rest on a thick basement membrane and associated with isolated regenerative intercalated cells.
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