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Sustaining apiculture worldwide has been threatened by bee diseases and unexplained colony losses. African honeybee populations seem healthier and no major losses have been reported despite the presence of all the major pests and diseases. The scattered colonies in the large wild population of the continent might ensure slow pathogen spread and thus protect the unmanaged colonies in comparison with the concentration of colonies in managed apiaries. Beekeeping and trade in bee products is responsible for spreading many diseases throughout the world. The recent outbreak of the bacterial disease American foulbrood (AFB) in South Africa is a matter of great concern. Despite a growing number of apiaries testing positive for AFB, no major colony losses have been reported yet. This could be based on higher disease resistance of African honeybees, but such a trait might not persist if pathogens accumulate in the hives. In the first part of this article we review what is known on the history, biology and epidemiology of AFB as well as the control methods available. We then argue that given the particular context of honeybees in Africa, protection policies need to be put in place to ensure that African honeybees remain healthy.
The eucalyptus snout beetle, Gonipterus scutellatus (Gyllenhal), introduced to South Africa from Australia, causes extensive damage to eucalyptus plantations in colder regions where biological control is less effective. A cytogenetic study was undertaken to assess the weevil's genetic recombination potential and thereby its ability to adapt to changing environmental conditions. During this study we investigated: (i) the sequence of meiosis; (ii) the weevil's karyotype; and (iii) the number and position of chiasmata on the bivalents. Squashes of male testes revealed a normal, chiasmate meiosis, a sex chromosome complement of Xyp and an autosome complement of three large, and two medium-sized, sub-metacentric pairs and seven small acrocentric pairs. The diploid chromosome number (2n = 26) is marginally higher than the ancestral chromosome number of the Curculionidae (2n = 22). Chiasmata were absent from the proximal regions of the bivalents, occurring mostly in the distal regions and less frequently in the interstitial regions. The mean of 15 chiasmata per cell was marginally higher than the number of bivalents (13); consequently, acrocentric and most sub-metacentric chromosomes displayed a single distal chiasma, while 2–3 sub-metacentrics also displayed a second distal or interstitial chiasma. The relatively low chromosome number and low frequency of chiasmata indicate that genetic recombination is controlled at independent assortment and crossing-over. This may limit the potential of G. scutellatus to proliferate under changing conditions and increase its pest status in the future.
Allodapine bees provide unique insights into social evolution because their method of provisioning brood in communal chambers differs from nearly all other social insects except ants. This method of brood rearing in allodapines is associated with the evolution of remarkable larval morphologies. Interestingly, allodapine larval morphology corresponds closely to phylogeny, more so than adult morphology. Here we describe a very unusual form of larval morphology in an African allodapine bee, Compsomelissa zaxantha, and show that this corresponds with phylogenetic analyses of DNA sequence data indicating that this species is much more closely allied with the genus Allodapula, but represents an evolutionary clade that differs strongly from currently described subgenera of Allodapula. We erect a new subgenus, Mhkuze, to contain this species and discuss the implications of this species for understanding the radiation in allodapine larval morphology.
Nine new species of Pseudomezium are described, and two previously described species are also considered. The unique morphological characteristics, including genitalia, of each species are illustrated and a key is given for all taxa. The morphological characteristics of the genus, including mouthparts and ventral structures are also illustrated. A brief discussion of the spider beetle diversity of South Africa and the potential of spider beetles for conservation efforts is also presented.
The Afrotropical eucoiline genus Stentorceps, described in 1984, has remained monotypic until now. Stentorceps is herein redescribed using recent field collections from Kenya and Madagascar. Stentorceps tubicen Quinlan is redescribed, and the new species S. abbotti, S. heimdalli, S. vuvuzela, S. weedlei and S. zuparkoi are described. Stentorceps heimdalli, S. weedlei and S. zuparkoi extend the range of Stentorceps to Nigeria, Madagascar, Rwanda, Somalia and South Africa. The descriptions and keys provide a foundation for future taxonomic and biological investigations.
A systematic revision of the mealybug genus Delottococcus Cox & Ben-Dov is presented. Nine species are treated, including D. millari which is described as new. The eight previously described species are: Delottococcus aberiae (De Lotto), D. confusus (De Lotto), D. elisabethae (Brain), D. euphorbiae (Ezzat & McConnell), D. phylicus (De Lotto), D. proteae (Hall), D. quaesitus (Brain), and D. trichiliae (Brain). Adult females of all species are described and illustrated and a key for their identification is presented. In the past, specimens determined as D. elisabethae have been recorded from citrus and other hosts, but these appear to be misidentifications of D. aberiae. Delottococcus elisabethae is only known from the original collection. As invasive species, D. confusus is reported from California and Hawaii, D. aberiae from Spain, and D. euphorbiae from France, Italy, and Sicily.
The effect of constant temperatures on the development, survival and fecundity of the oleander mealybug, Paracoccus burnerae, on citrus was determined. Developmental time, rate of development, fecundity and survival were investigated at five constant temperatures and a 16L:8D light:dark regime. The rate of development increased linearly with an increase in temperature for the egg, first nymphal and pupal stages as well as the entire development cycle from egg to adult, but was nonlinear for the second and third nymphal stages. Survival decreased with increase in temperature. Paracoccus burnerae required 666.7 degree-days above a lower threshold of 8.7 °C to complete one generation. The highest mean number of 68 eggs per female was recorded at 22 °C. A sex ratio of 1:0.92 (male:female) was obtained from the life table. The net reproductive rate (Ro) was >1 at all five temperatures, an indication that it is capable of increasing its population numbers despite the high mortality experienced in the first and second nymphal stages.
On 5 May 2010, Bactrocera invadens Drew, Tsuruta & White was detected in a methyl eugenol-baited surveillance trap in the northernmost part of the Limpopo Province in South Africa, an area adjacent to the Zimbabwe border. A delimiting survey was carried out to determine extent of spread in the area by trapping with both methyl eugenol and Biolure-3-component lures. A quarantine area of approximately 1100 km2 (surrounding the area of detection) was implemented to regulate movement of host fruits. Eradication of the pest was achieved in the quarantine area through male annihilation technique (MAT) using fibreboard blocks containing methyl eugenol and malathion in combination with protein bait sprays (application of GF-120 and LokLure mixed with malathion) and orchard sanitation. Eradication measures were carried out for a period of 12 weeks. Thereafter, MAT blocks were removed and trapping continued for a period of four weeks to confirm eradication. No B. invadens was caught in the area during the four weeks after control measures had stopped. No B. invadens was captured within a period of 12 weeks (approximately three generations) after the last fly find in the area. This constitutes the first successful eradication of B. invadens from an area of incursion.
The South African sister genera Parapseudosthenarus Schuh and Pseudosthenarus Poppius are revised. A monophyletic group containing both genera is diagnosed. Two new species of Parapseudosthenarus are described, bringing the total to three. Seven new species of Pseudosthenarus are described, bringing the total to 11. Morphological details are documented with light and scanning electron microscopy; whole insects are documented with colour digital photographs. Approaches to species discrimination are discussed. Parapseudosthenarus is shown to be broadly distributed across South Africa and Namibia whereas Pseudosthenarus is restricted to Namaqualand and the Little Karoo. Extensive host documentation is presented, indicating that both insect genera are restricted to plant genera placed in the tribe Crotalarieae (Fabaceae: Faboideae), and that most species are restricted to a single host genus; most Pseudosthenarus species breed only on the monophyletic Cape Group within Crotalarieae. Host plants are documented with colour digital images from the field and from herbarium specimens.
The false chinch bug, Nysius natalensis Evans (Hemiptera: Orsillidae), is a pest of sunflower, Helianthus annuus L. (Asteraceae), in South Africa. Pest outbreaks usually occur in localized areas towards the end of the summer. No information is currently available to predict these outbreaks. The effect of seven constant temperatures, namely 15, 19, 26, 28, 31, 36 and 38 °C on its reproduction, development and survival was determined. Longevity decreased as rearing temperatures increased. The optimum temperature for oviposition was between 26 and 28 °C with a mean of 246 and 276 eggs/female at 26 and 28 °C, respectively. There was also a significantly greater longevity compared to the other temperatures evaluated. No eggs were laid at or below 15 °C. Nysius natalensis could not complete its life cycle at 15 °C. The most favourable temperature range for development was between 26 and 36 °C. There was a strong positive linear relationship between temperature and the rate of development of the egg and nymphal stages as well as total development. Nysius natalensis required temperatures above a lower threshold of 14.0 °C, 13.97, and 15.2°C 14.8 °C for completion of the egg and nymphal stages, respectively, and from egg to adult stage. Degree-days required to complete the embryonic, larval and egg to adult stages were 74.6, 200.0 and 270.3 °D, respectively.
Several Mussidia species occur in West and East Africa, but only the ear-borer, Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae), has attained economic pest status in West Africa. During recent surveys in Kenya several parasitoid species were recovered from Mussidia species, including the egg parasitoid, Trichogrammatoidea sp. nr lutea Girault (Hymenoptera: Trichogrammatoidea). This parasitoid species is considered a potential biocontrol agent for M.nigrivenella in West Africa and development of a successful rearing system for its host, M.fiorri, will enable the mass production of this natural enemy species. The suitability of five artificial diets for the development of M.fiorii as well as optimum rearing conditions were evaluated in the laboratory. The effect of temperature and humidity on the development of M.fiorii was also studied. Mussidia fiorii successfully developed on maize leaf-, maize seed- and Canavalia ensiformes seed-based diets. The lower developmental thresholds for the egg, larvae, pupae, and egg to adult were 12.8 ± 0.25 °C, 14.4 ± 0.27 °C, 11.0 ± 0.03 °C and 13.5 ± 0.21 °C, respectively, while the thermal constants were 82.0 ± 1.61, 384.6 ± 9.4,144.9 ± 6.8 and 588.2 ± 10.8 degree-days, respectively. Information on dietary and thermal requirements will be used to optimize mass production of the host and natural enemies.
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