Afrobrianax, a new genus of the Eubrianacinae, with notes on its phylogenetic position and description of one new species from South Africa (Coleoptera: Psephenidae)

Lee, C-F.; Philips, T.K.; Yang, P-S.

Abstract: Afrobrianax, a new genus of the subfamily Eubrianacinae, is described using larvae, pupae and adults of a new South African species, Afrobrianax ferdyi. All African species of Eubrianax are transferred to Afrobrianax. A phylogenetic analysis of the Eubrianacinae, using 23 morphological characters (ten larval, four pupal and nine adult), was done and resulted in one most parsimonious cladogram. Afrobrianax appears as sister-group to Eubrianax and together this clade is the sister-group to Odontanax, Mubrianax and Jaechanax.

 

 

Arthropod fauna of mammal-pollinated Protea humiflora: ants as an attractant for insectivore pollinators?

Fleming, P.A.; Nicolson, S.W.

Abstract: Protea humiflora Andrews inflorescences are cryptic, but strongly scented and borne close to the ground (geoflorous) for ready access by small, non-flying mammals. During a study of P. humiflora pollination, we found that insectivorous elephant shrews (Macroscelididae: Elephantulus edwardii (A. Smith)) carried higher pollen loads on their snouts than simultaneously-trapped rodent species. Elephant shrews seem to be acquiring pollen while foraging for insects in the inflorescences. Compared with the larger bird-pollinated inflorescences of P. repens (L.) L., P. humiflora inflorescences have a substantially lower mass of arthropods, relatively fewer beetles (12 % of arthropod dry mass) and more ants (13 %). The large numbers of ants in these inflorescences may attract insectivore pollinators, suggesting an indirect, mutualistic relationship between plant, insect and insectivore.

 

 

Biological control of spear thistle, Cirsium vulgare (Asteraceae), in South Africa: a modest start for Rhinocyllus conicus (Coleoptera: Curculionidae)

Hodson, J.L.; Hoffmann, J.H.; Zimmermann, H.G.

Abstract: Rhinocyllus conicus is a flower-feeding weevil that has played a pivotal role in the biological control of several thistle species around the world. More recently it has achieved notoriety because of the damage it causes on several species of native thistles in North America. From 1984 to 1986, R. conicus was released for biological control of spear thistle, Cirsium vulgare, in three different regions of South Africa. Although the weevils have been established in the country since then, no proper surveys have been made to determine the extent of damage they are causing on C. vulgare. To redress the situation, samples of flower-heads from several localities were examined and damage due to R. conicus was recorded. The study showed that R. conicus has not dispersed more than 2.5 and 3.9 km from two of the original release sites where establishment was confirmed. The weevil is seldom particularly abundant (levels of damaged flower-heads exceeded 65 % at only two of 17 weevil-inhabited sites). Flower-heads set earlier in the season suffered higher levels of damage by the weevils, and infected flower-heads had significantly fewer seeds compared to uninfected flower-heads. All indications are that the contribution by R. conicus to biological control of C. vulgare in South Africa has been meagre due to unidentified constraints, at least in the two localized areas that the weevils currently occupy. Manual redistribution is required to determine whether or not other regions might be more suitable for R. conicus.

 

 

Indigenous plants and weeds on the Makhathini Flats as refuge hosts to maintain bollworm population susceptibility to transgenic cotton (Bollgard^TM)

Green, W.M.; De Billot, M.C.; Joffe, T.; Van Staden, L.; Bennett-Nel, A.; Du Toit, C.L.N.; Van der Westhuizen, L.

Abstract: The Makhathini Flats is mainly a small-scale farming area, with many farmers planting cotton varieties that have been modified to contain the Bt gene derived from Bacillus thuringiensis var. kurstaki (Bollgard^TM). This gene produces an endotoxin that provides resistance to attack from the bollworm complex. Cotton growers who plant transgenic cotton are required to plant a refuge area of non-transgenic cotton, as stated in the license agreement for Bollgard^TM. In addition to this requirement, indigenous plants and weeds were investigated as an additional refuge for bollworms. Scouting was used to monitor the number of bollworms (American or 'African' bollworm, Helicoverpa armigera (Hübner), spiny bollworms Earias biplaga Walker and Earias insulana Boisduval and the red bollworm Diparopsis castanea Hampson). Bollworm larvae were found to be present in high numbers on nine plant species that may serve as refuges. Abutilon austro-africanum Hochr. and A. sonneratianum (Cav.) Sweet, appeared to be the preferred alternative host plants of spiny bollworm.

 

 

Life history parameters of the biocontrol agent Gratiana spadicea (Chrysomelidae) reared on the natural host plant Solanum sisymbriifolium and the non-target crop Solanum melongena (Solanaceae)

Schachter-Broide, J.; Gandolfo, D.; Gurtler, R.E.

Abstract: Gratiana spadicea (Klug), a leaf-feeding tortoise beetle native to South America, was released in South Africa for the biological control of Solanum sisymbriifolium Lamarck (wild tomato), despite its ability to develop on cultivated eggplant (Solanum melongena L.) during laboratory host-specificity tests. Our studies in Argentina, during which beetle colonies were reared and sustained on both plant species, were aimed at determining whether a host range extension could be induced and thus whether eggplant crops may be under future threat in South Africa. During no-choice tests conducted under natural climatic conditions, larvae reared on potted eggplants suffered significantly higher mortality, longer developmental times and lower pupal masses than those reared on potted wild tomato. During choice tests under laboratory conditions, adult beetles fed significantly more on wild tomato than on eggplant, irrespective of whether the larvae were reared on eggplant or wild tomato, although the larger wild tomato-reared beetles consumed more than the smaller adults reared on eggplant. Under natural climatic conditions, females oviposited exclusively on wild tomato plants regardless of larval feeding history. During no-choice fecundity tests, females reared as larvae and adults on wild tomato had a significantly shorter preoviposition period and higher fecundity than females reared as larvae on wild tomato and as adults on eggplant, or as larvae and adults on eggplant. A significant percentage of females that spent part or all of their life cycle on eggplant laid only anomalous eggs (without a structure for leaf adhesion) or no eggs at all, whereas all females reared exclusively on wild tomato laid only normal eggs. The artificial rearing of G. spadicea on eggplant thus did not induce changes in adult feeding and oviposition preferences within the same generation, suggesting that eggplant is highly unlikely to serve as a viable alternative host for G. spadicea. Our study thus provides additional support for the decision taken to release G. spadicea in South Africa for the biological control of S. sisymbriifolium.

 

 

The relationship between citrus thrips, Scirtothrips aurantii (Thysanoptera: Thripidae), abundance and fruit size in mango orchards

Grove, T.; Giliomee, J.H.; Pringle, K.L.

Abstract: Population levels of the citrus thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae), were monitored for two consecutive seasons in mango (Mangifera indica L. (Anacardiaceae)) orchards in the Mpumalanga province of South Africa. Yellow sticky card traps were used to monitor adult numbers, while counts on the fruit were conducted to monitor numbers of adults and larvae. Fruit size was measured throughout the season. Hoerl's function (Y = aX^b e^cX) was used to describe the relationship between the number of S. aurantii on the fruit and fruit size, as well as the number on the traps and fruit size. A notable feature in the population dynamics of S. aurantii was the rapid decline in numbers after the population peak had been reached. The highest numbers of S. aurantii were present between fruit set and when fruit reached 40 mm in length. Fruit size can therefore be used as an indicator of potentially damaging number. Producers should do regular monitoring from fruit set until fruit reach 40 mm.

 

 

Biology of Mesoplatys ochroptera Stål (Coleoptera: Chrysomelidae), a pest of Sesbania species, in southern central Africa

Sileshi, G.; Sithanatham, S.; Mafongoya, P.L.; Ogol, C.K.P.O.; Rao, M.R.

Abstract: Sesbania species (Fabaceae) are a valuable plant resource in tropical agriculture. Recently, Mesoplatys ochroptera Stål (Coleoptera: Chrysomelidae) has become a serious pest of Sesbania species in agroforestry systems in Africa. The biology of M. ochroptera was studied in eastern Zambia and southern Malawi. Sesbania bispinosa (Jacq.) Wight, S. brevipedunculata Gillet, S. leptocarpa DC, S. macrantha Phil. & Hutch., S. rostrata Bremek & Obrem, S. sericea (Willd.) Link, S. sesban (L.) Merr. and S. tetraptera Hochst. ex Baker were the primary hosts of M. ochroptera in the study area. Females laid on average one egg batch per day in an oviposition period of 18-56 days. Egg batches contained 2-70 eggs. Females that were mated repeatedly produced about 1000 offspring while those mated only once produced 980 offspring. Larval development through three instars, took between 11-34 days. Pupal development occurred in the soil, and took 4-16 days. The survival and developmental periods of pre-imaginal stages differed significantly between the Sesbania species studied. The highest and lowest pre-imaginal survival was recorded on S. leptocarpa and S. rostrata, respectively. The longest developmental period of about 32 days was recorded on S. sesban while the shortest of 14 days was on S. leptocarpa. Annual activity cycle in M. ochroptera followed the unimodal rainfall pattern of southern central Africa. Beetles were only active during the rainy season (November-April) with a single population peak between February and April. Adults overwintered within and around the sesbania fallows during the long dry season (May-October) and emerged with the onset of the rains.

 

 

Leaf epicuticular wax ultrastructure and trichome presence on Russian wheat aphid (Diuraphis noxia) resistant and susceptible leaves

Bahlmann, L.; Govender, P.; Botha, A-M.

Abstract: The Russian wheat aphid (Diuraphis noxia) was first discovered on wheat in South Africa during 1978. It has since become a serious pest. The leaf epicuticular wax ultrastructure and leaf trichomes were examined on two Russian wheat aphid-susceptible wheat cultivars ('Palmiet' and 'Tugela') and a Russian wheat aphid-resistant wheat cultivar ('Tugela DN'). The lengths of the trichomes showed no significant differences in the three wheat cultivars examined. The resistant cultivar ('Tugela DN') had a significantly greater trichome density compared to the susceptible cultivars. Examination of the position of the trichomes revealed that there were differences for the adaxial and abaxial surfaces. Trichomes on all three wheat cultivars were found to occur mostly on the leaf veins of the adaxial surfaces, and on the leaf veins as well as between them on the abaxial surfaces. Leaf trichome density and position may act as a physical obstacle to Russian wheat aphid feeding as the aphid feeds on leaf veins of the adaxial leaf surfaces. The high trichome density on the leaf veins found in the resistant 'Tugela DN' cultivar could prevent the Russian wheat aphid from finding a suitable feeding site. Comparison of the scanning electron micrographs showed that the epicuticular wax structure was similar on both the adaxial and abaxial surfaces amongst the three wheat cultivars, and does not seem to affect Russian wheat aphid feeding.

 

 

Trends in codling moth activity in apple orchards under mating disruption using pheromones in the Elgin area, Western Cape Province, South Africa

Pringle, K.L.; Eyles, D.K.; Brown, L.

Abstract: The reliability of decisions regarding spray applications for the control of Cydia pomonella (L) using pheromone trapping in orchards under mating disruption and in orchards not under mating disruption was compared. Observations were made on the long-term trends in C. pomonella activity, pesticide use and damage levels in orchards under mating disruption. Decisions regarding spraying in orchards under mating disruption are less reliable than in orchards not under mating disruption (7 % and 3 % probability of making an incorrect decision respectively). Codling moth trap catches were reduced after the introduction of mating disruption at the two trial sites. This was accompanied by a reduction in the number of codling moth spray applications from eight to 3-5 at the first site. At the second site nine sprays were applied during the season before the use of mating disruption. During the first and second seasons of mating disruption eight and six applications respectively were made to reduce C. pomonella population levels. Thereafter the number of spray applications specifically for codling moth control varied from 3-4. Fruit damage at harvest did not exceed 0.23 % on the first site. On the second site there was 30-40 % fruit damage prior to mating disruption. This was reduced to 1.02 % during the first year after the introduction of mating disruption. Thereafter it did not exceed 0.58 %.

 

 

Revision of the mealybug parasitoids of the genus Pseudoccobius Timberlake (Hymenoptera: Encyrtidae) from South Africa

Prinsloo, G.L.

Abstract: The following six new species of mealybug parasitoids of the encyrtid genus Pseudococcobius Timberlake are described from South Africa: akares, ancylus, dolus, san, vibex and vinealis. Comments are given on the identity of the genus and generic placement of two extra-limital species, namely P. quingueguttatus (Girault) and P. melleicorpus (Girault); the latter species is synonymized with P. terryi (Fullaway). A key is provided for the recognition of the known species of Pseudococcobius.

 

 

The susceptibility of Aphelinus mali (Haldeman), a parasitoid of Eriosoma lanigerum (Hausmann), to pesticides used in apple orchards in the Elgin area, Western Cape Province, South Africa

Heunis, J.M.; Pringle, K.L.

Abstract: Aphelinus mali is the most important biological control agent of Eriosoma lanigerum, a serious pest of apples. The effects of 14 insecticides and 10 fungicides on the adult stage of the parasitiod, A. mali, were investigated under laboratory conditions. Some insecticides were also screened for their effect on the emergence of adult wasps from mummified aphids. Most chemicals were highly toxic to the adult wasps which succumbed within 24 h of exposure to the chemicals. Exceptions were endosulfan, two insect growth regulators and all fungicides tested. Percentage emergence of adult wasps from the mummies was high after treatment with all chemicals tested. However, in the case of chlorpyrifos more than 60 % of the parasitoid adults died soon after emergence, while nearly 30 % of the adults died soon after emerging from mummies treated with carbaryl (XLR Plus) and fenthion.

 

Paralamyctes (Chilopoda: Lithobiomorpha: Henicopidae) from the Cape region, South Africa, with a new species from Table Mountain            97

Edgecombe, G.D.

Abstract: Examination of type specimens and newer collections of Paralamyctes levigatus Attems, 1928, and P. tabulinus Attems, 1928, shows that both species belong to P. (Paralamyctes), the only subgenus of Paralamyctes represented in southern Africa. Paralamyctes (Paralamyctes) tabulinus is probably synonymous with P. (P. ) asperulus Silvestri, 1903. A new species from Table Mountain, P. (P.) prendinii, is distinguished by a maxillipede tooth form not otherwise known in Henicopidae. A key permits identification of the 24 valid species of Paralamyctes throughout the Gondwanan range of the genus.