African Entomology - Volume 21, Issue 2, 2013
Volumes & issues
Volume 21, Issue 2, 2013
Effectiveness of slow-release tablet formulations of the IGR diflubenzuron and the bioinsecticide spinosad against larvae of Aedes aegypti (L.)Source: African Entomology 21, pp 349 –353 (2013)More Less
The larvicidal effectiveness of slow-release tablet formulations of the chitin synthesis inhibitor Dudim® (diflubenzuron) and the bioinsecticide Natular (spinosad) against mosquito larvae of Aedes aegypti (L.) has been evaluated. The results showed that the test formulations provided long-term residual control against the larvae. Effective control giving 90-100 % inhibition of adult emergence was achieved for 10 weeks post-treatment for diflubenzuron and 7 weeks for spinosad. In addition, larval treatments with slow-release diflubenzuron formulations led to a marked prolongation in the time needed for blood meal digestion and a reduction in the reproductive potential of adult survivors. On the other hand, larval treatments with slow-release formulations of spinosad tablets affect neither the time of blood meal digestion nor the reproductive capacity of mosquito adults that emerged from surviving larvae.
Inventory of insect visitors, foraging behaviour and pollination efficiency of honeybees (Apis mellifera L.) (Hymenpoptera: Apidae) on plum (Prunus salicina Lindl.) (Rosaceae) in the Constantine area, AlgeriaSource: African Entomology 21, pp 354 –361 (2013)More Less
A list of insect visitors of plum was established during the 2009 and 2010 flowering period for an orchard in Constantine. Four orders of insects were encountered on flowers: Hymenoptera, Diptera, Lepidoptera and Coleoptera. The last three orders made very few visits. The honeybee was the most abundant visitor in both years, representing 79% and 78% of recorded visits. Foraging honeybees visited on average nine flowers per minute and 27 flowers per tree, and flights were most frequent between adjacent trees of different rows (56%). Only the flowers that received between three and five honeybee visits yielded fruit and the percentages of fruits formed were similar (31.6% and 30.4% in 2009 and 2010, respectively).
Genetic variation and invasion pattern of the Arabian rhinoceros beetle, Oryctes agamemnon arabicus (Burmeister) (Coleoptera: Scarabaeidae), in Tunisia, deduced from mitochondrial DNA sequencesSource: African Entomology 21, pp 362 –367 (2013)More Less
The Arabian rhinoceros beetle, Oryctes agamemnon arabicus (Burmeister, 1847), is an invasive species, introduced to Tunisia from the United Arab Emirates and causing serious damage to date palm trees in southern Tunisia. Considering the economic importance of this pest, it is necessary to understand the genetic diversity within and among its populations and investigate its dispersal mode. In the present study, the mitochondrial gene encoding the cytochrome oxidase subunit I (COI) was used to analyse the extent of genetic variation between samples of O. agamemnon arabicus, collected from geographically distant locations in Tunisia. A 505 bp DNA fragment, resulting from PCR amplification, was sequenced. Representative sequences were aligned, revealing nine polymorphic sites that identified eight haplotypes. Haplotype diversity (Hd) and Tajima's D neutral test were 0.707 and -0.043, respectively, indicating a low level of mtDNA variability. The calculated gene flow value was Nm = 0.47, indicating a high amount of gene flow occurring between populations from Tozeur and those from Kebili, although both departments are separated by the Chott-El-Jerid salt lake. The presence of common haplotypes between Tozeur and Kebili as well as the clustering pattern obtained by the NJ method confirmed this result. Based on these facts and considering the limited flight of O. agamemnon arabicus and its slow reproduction, it is likely that its expansion in Tunisia was facilitated mainly by human transportation of infected offshoots.
Biological notes on Aspidimorpha (Megaspidomorpha) angolensis Weise, 1896 (Chrysomelidae: Cassidinae: Aspidimorphini): host plant records, immature stages and cycloalexy : short communicationAuthor E. GrobbelaarSource: African Entomology 21, pp 368 –371 (2013)More Less
The South African cassidine fauna comprises about 126 species, belonging to 20 genera, and of these about 48 (~ 38.09 %) are endemic. Aspidimorpha Hope is a species-rich genus that occurs in the Old World and Australia, comprising 198 species. The subgenus Megaspidomorpha Hincks, one of the smaller of the 10 subgenera in the genus Aspidimorpha, contains three large Afrotropical species (Borowiec & Swietojanska 2013). They can be distinguished by the following: their size of 11mm or more in length; uniformly yellow pronotum which is very broad and has subangulate sides; uniformly yellow elytra with spots on the epipleura only, at most; elytra that are equal in width to, or slightly wider than, the pronotal base, regularly convex without a postscutellar tubercle or gibbosity, and puncturation that is irregular and dense; and claws that are pectinate on both sides (Borowiec 1997).
Are native predators likely to influence the establishment and persistence of Anthonomus santacruzi (Curculionidae), a biological control agent of Solanum mauritianum (Solanaceae) in South Africa? : short communicationSource: African Entomology 21, pp 372 –376 (2013)More Less
Solanum mauritianum Scop. (bugweed, woolly nightshade, Solanaceae), a perennial small tree that is native to South America, threatens several commercial and conservation activities in the eastern higher rainfall regions of South Africa and has thus been targeted for biological control (see review by Olckers 2011). The flowerbud-feeding weevil Anthonomus santacruzi Hustache (Coleoptera: Curculionidae), which has the potential to reduce the weed's excessive fruit set, was first released in South Africa in late 2008 (Olckers 2003, 2008) and is currently the subject of extensive release efforts to promote its establishment and distribution. Mass-rearing by the South African Sugarcane Research Institute since 2011 has so far facilitated the release of several thousand weevils in the province of KwaZulu-Natal (D. Gillespie, pers. comm.).
Effects of seed availability on egg distribution patterns and larval survival in Acanthoscelides macrophthalmus (Chrysomelidae: Bruchinae), a seed-feeding biological control agent of Leucaena leucocephala (Fabaceae) in South Africa : short communicationSource: African Entomology 21, pp 377 –382 (2013)More Less
Following widespread introduction for agroforesty, the Central American tree Leucaena leucocephala (Lam.) de Wit (Fabaceae) (leucaena) has become invasive, largely through excessive seed production, in several countries worldwide, including South Africa (Olckers 2011 and references therein). The seed beetle Acanthoscelides macrophthalmus (Schaeffer) (Chrysomelidae: Bruchinae) was released in South Africa in 1999 to increase seed mortality and thereby reduce further invasion, without compromising the plant's utilization (Shoba & Olckers 2010; Olckers 2011). The beetles lay their eggs on the outside surfaces of seed pods, or loose seeds that have been dehisced, and each larva burrows into a single seed which it destroys in completing its development (Shoba & Olckers 2010). Although the beetle has become widely established in South Africa (Olckers 2011), the levels of seed damage recorded so far have been erratic and relatively modest (Sharratt & Olckers 2012).
Source: African Entomology 21, pp 383 –387 (2013)More Less
All species have specific habitat preferences in which survival and reproduction are optimal. Understanding factors governing habitat selection is crucial in the field of community ecology and conservation biology (Schoener 1974; Pulliam & Danielson 1991; Morris 2003; Peterson & Dunham 2003; Johnson et al. 2004). Factors affecting a species' spatial distribution within a habitat are mainly the abiotic conditions, resource availability, predation, competition, and parasitism (Ricklefs & Miller 1999). During certain periods of their lifetime species are periodically vulnerable to abiotic and biotic external factors, making (micro-) habitat choice particularly crucial and producing direct and indirect demographic consequences on population and community (Cody 1985; Downie et al. 2004). Arthropod moulting is an example of such vulnerable life stages (Morgan & Miller 2005).
Source: African Entomology 21 (2013)More Less
Dorothy Gennard's role in the fourth-year course in Forensic Science at the University of Lincoln has placed her in an excellent position to design a text that caters for this level. It was generally agreed (e.g. Villet & Richards 2008; Higley & Huntington 2009) that the first edition of her book, published in 2007, was a useful text for teaching introductory courses in forensics, and this substantially revised edition is even better suited to that niche. Other recently revised texts are either difficult to acquire (Haskell & Williams, 2008) or more expensive reference works (Amendt et al. 2010; Byrd & Castner 2010).
Source: African Entomology 21 (2013)More Less
Life is about surprises, and if we are lucky they will primarily be welcome. My copy of this book arrived as a happy surprise in the mail, and my delight did not abate until I had finished reading it. I must admit that I have met and like many of the people mentioned in this book, and that I have a special and not unsentimental interest in cicadas, but I think that readers without such background will still find this book fascinating.