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Entomopathogenic nematodes (EPNs) represent an important part of the spectrum of potentially available biological control agents against insect pests. EPNs of the families Steinernematidae and Heterorhabditidae share a mutualistic relationship with bacteria of the genera Xenorhabdus and Photorhabdus, respectively. Current research on the use of EPNs against key pests of fruit crops in South Africa has the ultimate aim of using nematodes on a commercial scale against key insect pests of such fruit crops as deciduous fruit and citrus. For this objective to be realized, nematodes should be mass produced in vitro in liquid culture. A detailed understanding of the biology and behaviour of the nematode species and the associated bacterial symbiont in relation to their mass production is, therefore, required. The long processing time that is required for nematode cultures, combined with the need for an even distribution of fluids and organisms, result in the cultures being extremely vulnerable to contamination. Nematodes experience a very different environment in liquid culture than they do in nature, and a high level of technological knowledge is required for their successful production. Endemic EPNs are not currently commercially produced in South Africa. This review presents an overview of the current knowledge that is available on the bacterial symbionts and on the biology of the two nematode genera. Optimum growth parameters for the bacteria and the nematodes are discussed for endemic nematode isolates that might have the potential to be mass cultured for commercial application.
Hemijana variegata Rothschild, an edible caterpillar of Limpopo, South Africa, is little known to science but is a delicacy in the region. Harvesters believe the caterpillar is nourishing but there are no data on its nutritional value. This study reports on the proximate nutrient analysis of sun-dried (traditionally prepared) specimens and specimens oven-dried at 60 °C for three different time periods (24, 48 and 72 h). For the vitamin content analysis, fresh caterpillars were used. Drying at 60 °C for 24 h produced the highest energy value at 552 kcal/100 g while traditionally prepared caterpillars produce 306 kcal/100 g. The caterpillar was found to be rich in protein varying between 51 and 54 % for oven-dried and 44.5 % for traditionally prepared caterpillars. The fat content of 20 % is favourable, as is the percentage ash (10.47 % for traditionally prepared caterpillars), indicating elevated levels of nutrients. In fresh caterpillars, vitamin content was low for vitamin A (0.02 mg/100 g) and vitamin B1 (0.01 mg/100 g). Vitamin B2 (0.65 mg/100 g) and vitamin E (0.64 mg/100 g) were better represented. Vitamin C was high at 14.15 mg/100 g.
Heat shock proteins have been shown to play an essential role in protecting organisms from environmental stresses and can be divided into multiple families, including the heat shock protein 70 family. The family is composed of heat shock protein 70 (Hsp70) and heat shock cognate 70 (Hsc70). In the present study, to investigate whether the Hsp70 family plays an important role in the thermotolerance of Bombyx mori (silkworm), we analysed the expression of the Hsp70 family before and during heat shock in the midgut of three strains, including a thermotolerant strain cs-10, a thermosensitive strain cs-11, and cs-7, a thermotolerant near isogenic line of cs-11. qRT-PCR and Northern blot analyses revealed that, before heat shock, there was no significant difference in the expression of the selected four Hsp70 family members (Hsp70B, Hsp68, Hsc70-4 and Hsc70-3) among the three strains. Interestingly, after a heat shock of 2 h at 40 °C, increased expression of the selected four members was observed in all three strains, suggesting they are all inducible and involved in thermotolerance. Remarkably their expression, especially that of Hsp70B and Hsp68, was positively correlated with basal thermotolerance. After a heat shock of 8 h at 40 °C, there was no significant difference in the transcript level of Hsc70-3 between cs-10 and c-11. However, its transcript levels in both strains were still significantly higher than its pre-shock levels, indicating that Hsc70-3 may play an important role in long-term basal thermotolerance by working with other proteins yet to be identified. Unexpectedly, transcript levels of Hsp68, Hsc70-3 and Hsc-4 were found to be higher in cs-7 than in cs-10. A hypothesis is proposed to explain these results.
The codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), is a key pest of pome fruits in the Western Cape, South Africa. Up to 1993, the industry recommendation for commencement of the codling moth spray programme was at 75 % petal fall in order to avoid the negative impact of organophosphate sprays on bees during bloom. However, codling moth can emerge, mate and oviposit before and during full bloom in pome fruit orchards. Consequently, petal-fall does not necessarily correspond with the commencement of egg-laying or first egg hatch. The availability of insecticides with a softer environmental profile made it possible to apply sprays earlier than 75 % petal-fall. The development of phenology models provided a means of accurately predicting biological events such as the initiation of egg-laying and first egg hatch. Using lower and upper development thresholds of 10 °C and 32 °C, respectively, and hourly temperature recordings, phenology models were evaluated by comparing the number of degree-days (°D) accumulated using a selection of three biofixes, and date of first egg hatch. The number of °D accumulated from the selection of biofixes to first observed egg hatch varied from 130.7 to 179. The least variation in the number of °D between biofix and first egg hatch occurred when the second trap catch was used as the biofix. A biofix based on the first evening when the temperature reached or exceeded 17 °C at 18:00 after first trap catch also showed less variation than when the biofix was based on first trap catch. The mean number of °D at which 50 % of the moths of the first flight emerged was 166.6 °D, while the mean number of °D at which 50 % oviposition occurred was 290 °D following biofix. The number of °D between the second and third flight biofixes varied between 488.7 and 531.2 °D, with a mean of 508.1 °D. The results are of significance in improving the timing and reducing the number of insecticide sprays for codling moth control.
The compatibility of two endemic entomopathogenic nematodes (EPNs) with biological control agents and agro-chemicals, likely to be used in an integrated pest management programme for citrus in South Africa was investigated. This is the first report on the possible negative effect of EPNs against Cryptolaemus montrouzieri, a commercially produced biocontrol predatory insect, used against mealybugs. Bioassays were conducted to determine the susceptibility of the mealybug predatory coccinellid beetle, C. montrouzieri, to both nematode species. Results showed the beetle larvae to be highly susceptible to a concentration of 80 IJ/insect of H. zealandica and S. yirgalemense, obtaining 80 % and 92 % mortality, respectively. Adult beetles were found to be twice as susceptible to S. yirgalemense with 64 % mortality, as to H. zealandica with 30 % mortality recorded. Tolerance of both species of infective juveniles to aqueous solutions of Cyperfos 500 EC®, Cryptogran™, Helicovir™, Nu-Film-P® and Zeba®, for infectivity and survival was evaluated. Heterorhabditis zealandica proved to be highly compatible to all products tested, with no significant increase in nematode mortality. The formulations also did not affect the ability of H. zealandica to infect Tenebrio molitor, after exposure to products over a 24-h period. Significant increase in mortality of S. yirgalemense was recorded after 12 hours of exposure to Nu-Film-P® and Cyperfos 500 EC®, and after 6 hours of exposure to Nu-Film-P®. However, results for S. yirgalemense infectivity showed no decrease in the ability of the nematodes to infect insect hosts. Results indicated that nematodes should possibly be applied before the release of C. montrouzieri in citrus orchards.
Butterflies (Lepidoptera) have attracted more attention as bio-indicators of terrestrial ecosystems than other terrestrial arthropods. This study determined butterfly species turnover at a priori selected habitat patches inside Nduli Nature Reserve and its surrounding landscape, and their response to measured environmental variables. Using the line transect method, 516 butterfly individuals belonging to 22 species were sampled from all 16 sampling units (Sus), of which 13 species occurred in two or more Sus across the study site. Habitat patches outside the reserve were higher in butterfly species richness and abundance than inside the reserve. Papilio demodocus Esper, Borbo gemella Mabille, Precis octavia (Cramer) and Hypolimnas missipus (Linnaeus) were each restricted to one sampling unit. Hierarchical clustering using Bray-Curtis similarity matrices and correspondence analyses grouped sampling units according to butterfly species sampled. Canonical correspondence analysis results indicated that certain site (environmental) variables, e.g. percentage herb cover, grazing intensity, distance to the city centre and average flower density accounted for species distribution patterns across Sus. The implications of the study suggest that habitat patch level management for conservation action should aim at preserving sufficient herb cover and nectaring plants, especially during the summer season to cater for all developmental stages of butterfly species in the study area. Furthermore, species richness within the reserve can be encouraged by using vegetation linkages and corridors between the reserve and its surrounding landscape. Butterflies identified during the study can serve as indicator species for assessing the conservation value of habitat patches in the study area and for increasing public awareness of the need to conserve butterflies and the invertebrate fauna of the King Sabata Dalindyebo Municipality between the months of November and April.
The blue gum chalcid, Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae: Tetrastichinae) is widely distributed in Africa, America, Europe and Asia. Destructive damage of this wasp has been given much attention by many biologists and entomologists. We reviewed the invasive biology, distribution, mode of spread and situation of management of L. invasa in view of the status of rapid spread and serious damage. Research directions and methods of further studies were proposed, including reproductive mode and population expansion, impact factors and the formation mechanism of inducing gall, flight capacity of the wasp, effects of the ecological environment on distribution and occurrence, and control strategies. This information is beneficial to explore the mechanism of invasion and outbreak of invasive species.
Commercial use of entomopathogenic nematodes against key insect pests of deciduous fruit, grapes and citrus in South Africa requires massive numbers of nematodes for inundative field application. High-technology in vitro liquid culture requires development to mass culture and to formulate these nematodes for commercial purposes. Heterorhabditis zealandica was identified as a species with potential as a biological control agent against a wide range of key insect pests. The first step towards the development of in vitro mass culture of H. zealandica was to establish monoxenic cultures of both the nematode and its Photorhabdus sp. symbiont, using in vitro liquid culture technology. The body length of various H. zealandica life stages during in vitro development was measured to determine the growth characteristics of H. zealandica in liquid culture. The growth curve of the symbiotic bacteria during the process time was measured to determine when the stationary phase was reached, as this would indicate the optimum time required for inoculating infective juveniles (IJs) and for aiding in maximum IJ recovery. On day 15, the IJs reached a maximum density of 41100/ml, while the hermaphrodites and females reached their highest density on day 16 at 9800/ml and 7700/ml, respectively, after which the experiment was terminated. Bioassays using Galleria mellonella were performed to compare the virulence between in vitro- and in vivo-produced nematodes, which indicated in vitro-produced nematodes to be significantly less virulent. This study illustrates that H. zealandica and its Photorhabdus sp. symbiont can be successfully cultured in liquid. However, two generations occurred during the process time, instead of the desirable one generation. Future research goals would include developing methods to increase the percentage recovery in the liquid culture, as doing so would increase the number of nematodes produced per ml and it would also reduce the processing time significantly.
Date palm (Phoenix dactylifera L.) is one of the oldest fruit crops of the world having been cultivated for many centuries in North Africa and the Middle East. In Saudi Arabia commercial date palm production is an important industry. Insects, excluding the Lepidoptera, were sampled with Robinson-type light traps placed in 16 date palm commercial orchards in the Al-Kharj region, Riyadh Province, Saudi Arabia, for 12 months from June 2007 to May 2008. No insecticide treatments or manure fertilizer applications were made in the orchards during operation of the traps. A total of 44 485 insects representing nine orders (Orthoptera, Blattodea, Dermaptera, Hemiptera, Mantodea, Neuroptera, Coleoptera, Hymenoptera and Diptera) and at least 50 different taxa were counted and identified. Most of the insects were trapped during a period extending from mid-Spring (April) to early autumn (September). The highest numbers were trapped during July and August (87 % of the total). Two orders, Coleoptera and Diptera represented 97 % of all insects trapped. Beetles comprised 87.83 % of the total insects trapped with scarabs composing 73 % of this percentage. The fruit stalk borer Oryctes elegans comprised 58 % of that total. This species was exceptionally abundant in one of the orchards in August. Dipterans comprising 10 % of the total (4 701 individuals), was the only other order attracted in relatively large numbers to the light traps. Most of these flies were trapped during August. The sericine scarab Maladera insanabilis previously not known from date palm orchards of Saudi Arabia may be a potential new pest.
Aethioeubria occidentalis gen. and sp. n. is described from southern Mali and southeastern Senegal, representing the first member of the subfamily Eubriinae from the African continent. Due to the randomly distributed elytral granules, pectinate male antennae, apically bifurcate male claws, and strongly sclerotized and Y-shaped fibula of the median lobe, the new genus is similar to the Asian genus GranuleubriaJäch & Lee, 1994. However, Aethioeubria gen. n. differs from that genus by the smaller male eyes, pointed terminal labial palpomere, claws without angular bases, and the smooth posterior margins of abdominal ventrites II–IV. A new phylogenetic analysis of the subfamily Eubriinae is provided. The biogeography of the genus is briefly discussed.
The nutritive benefits of the catfish, Clarias gariepinus (Burchell, 1822), are threatened by its infestation by Dermestes maculatus DeGeer, 1774 during storage. The influence of D. maculatus on stored C. gariepinus was investigated in this study. Fifty smoked C. gariepinus (117.5 ± 0.05 g) were sterilized by oven drying and randomly allotted into 10 boxes. Each box contained five fishes which were infested with larvae of D. maculatus at the beginning of the experiment and were stored for 0 (control), 14, 28, 42, and 56 days. The weight loss and proximate composition (crude fibre, ash, protein, fat, carbohydrate, Na, K, Mg and Fe2 ) of the stored fish samples were analysed at the end of each period. The storage periods represented the treatments. Results revealed that the weight of experimental smoked fishes decreased as the storage duration increased. Similarly, the crude protein, ash and carbohydrate content of C. gariepinus decreased as the days of infestation increased (crude protein varied from 67.00 % at day 0 to 36.84 % at day 56). The mineral composition of the experimental fishes likewise decreased with days of infestation. Regression analysis showed a strong positive relationship between protein ( 0.95), fat ( 0.90), K ( 0.80) content of the fishes and duration of infestation. Thus, the nutritive quality of C. gariepinus is highly reduced by D. maculatus infestation.
The direct impact of broad-spectrum insecticides on primary parasitoids is considered a major contributing factor to the high pest status of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in many parts of the world. As a result, selective insecticides are often put forward as a solution to the problem of integrating chemical and biological control methods. However, there is paucity of studies that have directly contrasted effects of selective and broad-spectrum insecticides on parasitism rates and parasitoid species richness in the field. We compared effects of weekly and bi-weekly application regimes of a selective insecticide (Dipel®) and a broad-spectrum insecticide (dichlorvos) on parasitism rates of P. xylostella and species richness of its primary parasitoids against unsprayed control for two cropping seasons. Parasitoids were reared from immature P. xylostella in all treatments, and parasitism rates were not significantly different among the treatments. During October–December 2011, four species of primary parasitic Hymenoptera [Cotesia vestalis (Haliday) (Braconidae), Apanteles halfordi (Ullyett) (Braconidae), Oomyzus sokolowskii (Kurdjumov) (Eulophidae), and Diadromus collaris (Gravenhorst) (Ichneumonidae)] were reared from P. xylostella larvae and pupae, whereas three parasitoid species (C. vestalis, O. sokolowskii and D. collaris) were reared during March–May 2012. Cotesia vestalis accounted for >80%of total parasitism rates in all treatments. In both seasons, parasitoid species richness was highest on the control treatment. Although two parasitoid species were recorded on all Dipel® and dichlorvos treatments during October–December 2011, only one parasitoid species was recorded on Dipel® treatments during March–May 2012 compared to two species on dichlorvos treatments. Thus, insecticide application regime had no influence on parasitoid species richness, instead insecticide type did. Since P. xylostella infestations were significantly lower in Dipel® treatments in both seasons, this study suggests that a greater impact of a selective insecticide on the pest population density can affect parasitoid species richness more than the direct impact of a broad-spectruminsecticide with a short crop residual period.
Trioza erytreae (Del Guercio) (Hemiptera: Triozidae), is a minor pest of citrus, but the significance of this triozid is attributed to its ability to vector the African citrus greening disease pathogen, ‘Candidatus’ Liberibacter africanus. The population fluctuation of T. erytreae is correlated with the flushing rhythm of the citrus host. However, seasonal fluctuation in the infection potential of populations carrying the greening pathogen has been difficult to monitor in the past due to limited detection methodologies. This study explored the fluctuation in infectivity in an orchard severely infected by African greening. Two seasons' data are presented from a small Citrus aurantium (L.) (sour orange) orchard in the Nelspruit district in South Africa. Individual T. erytreae caught weekly on sticky traps placed in the orchard were tested using PCR. Additionally, a T. erytreae outbreak was observed in 2011 in another C. sinensis (L.) Osbeck (sweet orange) orchard which displayed a high incidence of greening also in the Nelspruit district. T. erytreae collected here were used in a challenge study and some transmission data are presented. T. erytreae population fluctuations followed the citrus growth flush cycles and were influenced by specific climatic factors. Fluctuations in the percentage infectivity of the T. erytreae populations were observed, with infectivity peaking with or just after the citrus flush seasons, but with peaks in infectivity differing to peaks in population of the vector. In a challenge study, the percentage pathogen transmission to citrus was much lower than the detected percentage infection of the triozids used for the study.
The present study was designed to investigate the activities of the detoxifying enzymes acetylcholinesterase (AChE), non-specific esterases (α- and β-esterases), glutathione S-transferase (GST) and mixed-function oxidases (MFO) in spinetoram-treated Agrotisipsilon (Hufnagel). For this purpose, fourth larval instars were exposed to three sub-lethal concentrations (LC10, LC20 and LC50) of spinetoram for 24 h using the leaf dipping technique. The activities of detoxifying enzymes in the survivors after 2, 4 and 6 days of treatment were compared to non-treated larvae (control). AChE activity was significantly increased after 4 and 6 days of treatment with the LC10. In contrast, this activity was significantly decreased after 2 days of treatment with the three sub-lethal concentrations applied, and after 4 and 6 days of treatment with the LC20 and LC50. While both α- and β-esterase activities were significantly enhanced after 2 days of treatment with all the previous sub-lethal concentrations, with no constant pattern after 4 and 6 days of treatment. GST activity was significantly increased on the second day of treatment with the LC10, and on the fourth day of treatment with the LC10 and LC50. Whereas the only significant decrease in GST activity was observed on the sixth day of treatment with the LC10. No significant change was recorded on the second and sixth days of treatment with the LC20 and LC50, and on the fourth day of treatment with the LC20. The activity of MFO was significantly enhanced up to the fourth day of treatment with all the concentrations investigated, whereas this activity was significantly decreased on the sixth day of treatment. Therefore, it appears that higher activities of detoxifying enzymes in A. ipsilon generally occurred in response to the intoxication by the lowest concentration of spinetoram, particularly after a relatively early time of treatment, and MFO may be considered the principal detoxifying enzymes.
Aphid landing rates, species composition and abundance on lucerne (Medicago sativa), maize (Zea mays), soybean (Glycine max), wheat (Triticum aestivum) and potato (Solanum tuberosum) were determined in a small-scale field trial to identify potential crops as prospective border plants for seed potatoes to reduce the spread of Potato virus (PVY) in South Africa. Aphids were sampled using green bucket traps to estimate aphid landing rates, whereas leaf counts and sweep-netting were used to identify colonizing species. Of the 34 species or species groups collected with green bucket traps, 18 were previously known vectors of PVY. The most abundant vector species or species groups were Acyrthosiphon pisum, Macrosiphum euphorbiae, Metopolophium dirhodum, Myzus persicae, Rhopalosiphum padi and Sitobion spp. The only other species that occurred in high numbers, but whose vector status is unknown, were Acyrthosiphon kondoi and Tetraneura fusiformis. Landing patterns suggest that A. kondoi, A. pisum and M. dirhodum may be able to discriminate between plant species and select their preferred host plant, if available within a habitat patch, in the pre-alighting phase, whereas other species such as R. padi seemed less selective. Results on aphid landing together with colonization of the crops evaluated suggest that maize and wheat show the highest potential as possible crop border plants in regions where aphids colonizing Poaceae, and lucerne in regions where aphids colonizing Fabaceae are abundant. Soybean appears to be less suitable because cultivars with a high trichome density, which reduces colonization by aphids, are preferentially planted in South Africa.
The consumption of insects, especially termites, has over the years gained attention. This study aims at evaluating the nutritional and heavy metal levels in workers, soldiers and primary reproductives of Macrotermes bellicosus (Smeathman) collected from farmland, a dump site and an industrial estate in Abeokuta, southwestern Nigeria. Proximate analysis was done using standard methods, vitamins were analysed spectrophotometrically while minerals and heavy metal analyses were done using an atomic absorption spectrophotometer. The soldiers and worker termites recorded higher values of ash, crude fibre, crude protein and carbohydrate contents than reproductive termites (queen and king). The reproductives recorded higher fat content than workers and soldiers. The highest ash (2.27 ± 0.02 %), crude fibre (1.04 ± 0.02 %), crude protein (20.96 ± 0.01 %) and carbohydrate contents (3.65 ±0.01 %) were recorded for workers and soldiers collected from the industrial estate. The reproductives from farmland recorded the highest average vitamin contents, 16.96 ± 0.01 mg/g of vitamin A, 2.74 ± 0.01 mg/g of vitamin B and 7.15 ± 0.02 mg/100 g of vitamin C. The lowest vitamin A and B contents recorded for soldiers from the dump site were 15.12 ± 0.01 mg/g and 2.09 ± 0.01 mg/g, respectively, while soldiers from the industrial estate had the lowest (4.51 ± 0.01 mg/100 g) vitamin C content. Castes from the industrial estate had the highest amount of Cu2 (0.076 ± 0.001 mg/1) while the highest values of Cr2 0.226 ± 0.001 mg/1 and 0.223 ± 0.003 mg/1 were recorded for workers from farmland and the dump site, respectively. Lead Pb2 was only detected in the soldier castes. From the results, it can be concluded that termites are rich in crude protein and have a very low tendency to accumulate heavy metals from the soil.
The demand for honey and other beehive products has necessitated different methods of hunting ranging from wild to modern beekeeping methods. The influence of two different nesting habitats on the gut enzyme activities and heavy metal content of honey-bee workers was investigated in this study. Worker bees of Apis mellifera L. were randomly collected from the wild and Kenya top bar hives were analysed for the presence of heavy metals (Pb, Zn, Cd, Mn and Cu). Gut enzymes (cellulase, amylase, a-glucosidase, proteinase and lipase) assay was also determined in worker bees from the two habitats. Worker bees from the Kenya top bar hives recorded significantly higher heavy metals in their body than worker bees from the wild. Similarly, no Cd and Pb were detected in the body of worker bees from the wild. The gut enzymes assay of worker bees from Kenya top bar hives revealed the presence of cellulase, amylase, glucosidase, proteinase and lipase with a significantly higher enzymes activities (1.10, 1.65,0.89, 0.61,0.23 Absorbance/min for cellulase, amylase, proteinase, lipase and a-glucosidase, respectively) than wild worker bees. It can thus be concluded that nesting habitats influenced workerbees heavy metal composition and gut enzymes.
While many studies have been conducted on possible effects of Bt-maize on beneficial arthropods, information on its effects on non-target pests of maize is scarce. Bt-maize has been planted in South Africa since 1998 for control of the maize stem borers, Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Pyralidae). No information is available on the possible effects that feeding on Bt-maize may have on other pests exposed to Cry1Ab protein when they attack seedlings or ears of Bt-maize. Important pests attacking maize seedlings are Heteronychus arator (Coleoptera: Scarabaeidae) and Somaticus angulatus (Coleoptera: Tenebrionidae), while Helicoverpa armigera (Lepidoptera: Noctuidae) is a sporadic pest of maize ears. The objectives of this study were to determine the effects of Bt-maize, expressing Cry1Ab protein, on these non-target pests. Laboratory studies in which larvae or adults of these species were fed with Bt and non-Bt-maize leaves or ears were conducted and mortality, growth, fecundity and fertility determined. Feeding on Bt-maize did not have a significant effect on any of these life-history parameters of H. arator or S. angulatus. In greenhouse and laboratory studies with H. armigera no larvae survived to the pupal stage on Bt-maize. This study showed that Cry1Ab-producing maize may protect the crop against H. armigera feeding damage. However, the likelihood of H. armigera becoming resistant to Cry1Ab protein over time, and it becoming an important secondary pest, is high.
The genus Mescirtes is recorded from Africa for the first time. Seydelicyphon Pic is a new junior synonym of Mescirtes. Mescirtes nigronotatum (Pic) is redescribed and a new locality is reported. Four new species are described: M. camerunensis sp. n. (Cameroon), M. ibadanensis sp. n. (Nigeria), M. krugerensis sp. n. (South Africa), and M. ruthmuellerae sp. n. (South Africa). Notes on morphology, distribution, and a key to African species are included.
Physical aspects of macadamia orchards appear to play an important role in the distribution patterns of indigenous heteropterans. Increasing tree density and tree height appear to be associated with increases in insect damage. Very dense orchards not only provide these insects with an ideal sheltered habitat, it also reduces the efficacy of many air-assisted sprayers commonly used for insect control in this crop. Macadamias are very tall trees and heteropterans seem to have a preference for nuts occurring in the higher tree strata. The reason for this is unclear at the moment but it might be related to thermoregulation or lekking behaviour. Heteroptera damage was also confined to the edges of many orchards especially during the early season and it is speculated that perimeter trees may temporarily act as a barrier, preventing migration deeper into the orchards. Implications of these findings for an IPM programme are discussed and include: perimeter spraying during the early season as opposed to a full cover spray, tree pruning as well as tree height management.
A survey of Coccinella septumpunctata on alfalfa Medicago sativa L. was carried out during spring in 2013 at Farafra and Bahariya Oases in Egypt. Insects were collected from six different regions located in the two oases. Genetic diversity within the species was accessed by using five RAPD markers. A total of 55 fragments were amplified, of which 48 fragments were polymorphic showing 87.3 % polymorphism. The number of amplification products ranged from nine to 15 with an average of 12 per primer. The maximum of polymorphic bands (15 bands) belonged to K15 primer, whereas the minimum of polymorphic bands (7 bands) belonged to C15 primer. Genetic characterization was done with the help of similarity matrix. The similarity of DNA bands ranged from 0.578 to 0.774.
The use of synthetic organic pesticides has serious economic, social and environmental ramifications. Thus, this study describes the experiments using botanical and bacterial extracts to control the samsum ant (Pachycondyla sennaarensis). This ant is widely distributed in many parts of southern Saudi Arabia, and has been established as a household pest ant. Three Saudi plants, harmal (Rhaza stricta), boxthorn (Lycium shaivii) and artemisia (Artemisia inculta) and two bacterial extracts, Pseudomonas frederiksbergensis and Streptomyces sp. were tested in a minced meat bait against the workers of samsum ant. Among the plant extracts tested, ata concentration of 0.3 mg of the plant extract of boxthorn per gram of food exhibited the highest toxicity to samsum ants, causing 20.30 % mortality per day and 100 % average death rate of all the ants in 4.9 days. Furthermore, the results demonstrate that the bacterial extract of Streptomyces sp. was the most effective agent to control these ants, with the average death rate at 30 ants per day at a concentration of 0.3 mg/g food.
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