African Entomology - Volume 8, Issue 2, 2000
Volumes & issues
Volume 8, Issue 2, 2000
Source: African Entomology 8, pp 157 –168 (2000)More Less
The application of a model modified from Jeffree & Jeffree (1994) for investigating the distribution responses of selected antlion species to a climate change scenario was explored in this study. Modifications include a multivariate capability that facilitates the incorporation of precipitation seasonality, and provides useful output in the form of probability of occurrence values for each species. The model can be used to interpolate the distributions of poorly sampled taxa as well as predict responses to a changing climate. It is predicted that species from the more arid western parts of South Africa will be subject to severe range contraction and range shifts whereas the species from the more mesic eastem parts will experience range contraction with limited range shift. The likelihood of successful range shifts will be affected by the nature of novel communities, habitat suitability and the degree of land transformation. Given the extent of the predicted spatial responses, conservation planners can no longer afford to ignore future climate impacts on species distribution patterns.
Influence of insect infestation on aflatoxin contamination of stored maize in four agroecological regions in Benin (EntomologySource: African Entomology 8, pp 169 –177 (2000)More Less
Insect species and damage levels were evaluated and related to aflatoxin content in maize sampled from farmers' stores in four agroecological zones over a two-year period in Benin, West-Africa. In 1993, no aflatoxin was detected in maize that was free of isect damage. In the same year; in maize with more than 70 % of cobs damaged by insects 30.3 % were aflatoxinpositive, with a mean aflatoxin contamination of 77.8 ppb (parts per billion or kg). Grain moisture increased with damage levels. The mean aflatoxin content of maize infested with Carpophilus dimidiatus Fabricius (Coleoptera: Nitidulidae) was significantly higher than maize free of this pest (F = 5.05, P ~ 0.05). In 1994/95, the density of Mussidia nigrivinella Ragonot (Lepidoptera: Pyralidae), was significantly higher in the Northern Guinea Savanna than in the other zones, and the presence of this pest was positively correlated with the cob area visibly infected with Aspergillus jlavus Link (Deutoremycetes: Monoliales) (r = 0.239, P ~ 0.05) early in storage. Six months later, damage levels due to insects were significantly lower in the Sudan Savanna than in the other ecozones. The infestation level of the most common storage pest, Sitophilus zeamais Motschuisky (Coleoptera: Curcilionidae) decreased from the south to the north. After six months of storage aflatoxin level was positively correlated with the cob area damaged by Sesamia calamistis Hampson (Lepidoptera: Noctuidae) (r = 0.25, P ~ 0.05), the number of Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae) observed on maize (r =.26, P ~ 0.05) and cob area damaged by S. zeamais (r = 0.22, P ~ 0.05).
Oviposition preference of Sulcobruchus subsuturalis (Pic) (Coleoptera: Bruchidae), an introduced natural enemy of Caesalpinia decapetala (Roth) Alston (Caesalpiniaceae) in South Africa : short communicationAuthor W. CoetzerSource: African Entomology 8, pp 173 –176 (2000)More Less
Anatomy and histology of the alimentary canals of the antlion larvae Furgella intermedia Markl and Palpares annulatus Stitz (Neuroptera: Myrmeleontidae), with reference to their feeding physiologySource: African Entomology 8, pp 179 –188 (2000)More Less
The anatomy and histology of the alimentary canal, mouthparts and mandibular-maxillary glands of larvae of Furgella intermedia Markl and Palpares annulatus Stitz were studied to determine the mechanisms involved in feeding and the adaptations for optimal use of ingested food during non-feeding periods. A scletorized canal was observed within the maxilla of the larva of Crambomorphus sinuatus (Olivier). Palpares annulatus and F. intermedia have several anatomical features that are characteristic of Myrmeleontidae and enable antHon larvae to exploit periods of food abundance and to survive long periods of food shortage. When food is ingested, the intima of the crop and rectal pouch, and the regulatory effect of the proventriculus prevent the disruption of the osmotic balance in these larvae. Food is retained in the midgut, as the midgut is discontinuous with the hindgut. Six of the eight Malpighian tubules are cryptonephric and end in a pear-shaped organ that is laterally displaced on the rectal pouch. The cryptonephric system, Malpighian tubules and the modified cuboidal epithelium of the rectal fold regulate the water balance of these larvae.
Author J.G.H.** Dikow, T.* & LondtSource: African Entomology 8, pp 189 –200 (2000)More Less
The genus Lamyra Loew is reviewed. Four species are recognized, L. greatheadi Oldroyd, L. gulo (Loew), L. rossi Oldroyd, L vorax Loew. A key for theiridentification and comments on their distribution and biology are provided. Redescriptionptions of L. greatheadi and L rossi are given. Laphria nobilis Walker is confirmed as a synonym of L vorax. The genus is widely distributed in the Afrotropical Region, but also occurs in Israel.
Reproductive potential of Eupelmus orientalis (Crawford) and Eupelmus vuilleti (Crawford) (Hymenoptera: Eupelmidae), two parasitoids of Bruchidae (Coleoptera) during the harvest and storage of cowpea pods (Vigna unguiculata (L.) Walp.)Source: African Entomology 8, pp 201 –209 (2000)More Less
Eupelmus orientalis (Crawford) and Eupelmus vuilleti (Crawford) are two closely related ectoparasitoids that parasitize the larvae and pupae of Bruchidius atrolineatus Pic and Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) in the Niamey Region of Niger, West Africa. In this Sahel Region, these solitary parasitoids occur sympatrically in the field crop of cowpea, Vigna unguiculata, (L.) Walp. (Leguminosae), and during subsequent storage in granaries. In the Niamey Region the storage of cowpea seeds corresponds to the period of transition from summer (23-33 0c) to winter (15-25 DC). With C. maculatus as host, the reproductive potential (number of eggs laid, hosts parasitized and offspring produced) was similar in both parasitoid species in the summer, the only major difference between the two being the sex ratio of the progeny. In E. orientalis 50 % of the offspring were females compared to 60 % in E. vuilleti. In cooler winter conditions, all aspects of reproductive potential were greater in E. orientalis females than in E. vuilleti. Under these conditions development times were shorter for E. orientalis than for E. vuilleti, although E. orientalis had a longer life span. EupeImus orientalis females were more effective than E. vuilleti at parasitizing their common host. This advantage was confirmed by their intrinsic growth rate (rm) during both seasons. Despite this, the population of E. orientalis decreased during storage, and disappeared within two months, while the population of E. vuilleti became dominant. The disappearance of E. orientalis during storage cannot be attributed directly to a temperature-related loss of reproductive potential with the advent of the cooler season
Author I.** Hernando, C.* & RiberaSource: African Entomology 8, pp 211 –216 (2000)More Less
The Afrotropical genus Cyclolimnichus Deleve is revised. The only previously descriptionbed species in the genus, C. presignis Deleve, is redescriptionbed and three species, C. dentoni and C. ovalis from Cameroon and C. jaechi from Kenya, are descriptionbed as new. Two species groups are identified according to external morphology and male genitalia, the first comprises C. presignis and C. jaechi, and the second C. ovalis and C. dentoni. A key to the species of Cyclolimnichus is provided.
Control of the brown locust, Locuslana pardalina (Walker) (Orthoptera: Acrididae), using a mycoinsecticide: addressing the issues of speed-of-kill, dose rate, mortality and reduction in feedingAuthor E.J. MullerSource: African Entomology 8, pp 217 –221 (2000)More Less
Metarhizium anisopliae var. acridum (Deuteromycotina: Hyphomycetes) mycoinsecticide acts through direct contact and provides control equal to that of chemical insecticides in current use, although the speed-of-kill is slower. To test the dose-mortality response, doses ranging from 103_108 conidia per insect were tested in the laboratory against fifth instar brown locust hoppers, Locustana pardalina (Walker). At the highest dose (10 8), all insects died after 3-4 days, while 100 % mortality was achieved with the 107 and 106 dosage rates after five and six days, respectively. The 105 dose took 6-10 days to achieve 100 % mortality and a dose of 104 took 12-14 days to achieve mortalities of 75-87 %. The lowest dose rate (103) produced no significant mortality before 9-10 days after inoculation, with final mortality reaching only 60 % after 21 days. This was a classic dose response. Locusts are pests because of the crops and pastures that they consume and any reduction in food consumption is consequently of great value. All preliminary laboratory treatments caused a reduction in food consumption, even at a dose rate of 104 conidia per locust. These results may influence the future operational implementation of the mycoinsectidde in the field.
A sampling system for estimating population levels of the citrus thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae), in mango orchardsAuthor K.L.** Grove, T.* & PringleSource: African Entomology 8, pp 223 –226 (2000)More Less
Data were collected over a two-year period at four localities in Mpumalanga Province, South Africa, to formulate a sampling technique for monitoring population levels of the citrus thrips, Scirtothrips aurantii Faure, in mango orchards. Using a two-stage sampling system for determining population levels, the optimum combination of the number of trees per orchard (primary units) and fruit per tree (secondary units), was estimated. Taylor's power law regression of log(S2) on 10g(X. . ) provided a good fit for both the within-tree (r-2 = 0.887) and between-tree (r-2 0.746) data. The value for the aggregation coefficient, b, in both cases was > 1, indicating a dumped distribution. Sampling precision, D, improved with increasing average numbers of S. aurantii pedruit. ln addition, keeping the total number of fruit examined constant, sampling precision at low population levels improved by increasing the number of trees sampled and decreasing the number of fruit examined per tree. Examining 50 fruit per orchard should be sufficient for obtaining suitably accurate population estimates for pest management purposes.
A new genus and species of trichome-bearing dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) from South AfricaAuthor C.H. Philips, T.K. & ScholtzSource: African Entomology 8, pp 227 –231 (2000)More Less
The first South African genus and species of myrmecophilous Scarabaeidae with trichomes is descriptionbed. The other Old and New World genera of myrmecophilous dung beetles are listed, and morphology and biologies are compared with this new species. The tribal placement of the new species is uncertain but character states indicating that the species could provisionally be placed in the Onthophagini are discussed.
Fecundity, fertility and phenology of white wax scale, Ceroplastes destructor Newstead (Hemiptera: Coccidae), on Citrus and Syzygium in South AfricaSource: African Entomology 8, pp 233 –242 (2000)More Less
The population density of Ceroplastes destructor Newstead has increased steadily since 1994, particularly on Citrus reticulata (Blanco), in'citrus-growing areas of the Western and Eastern Cape Provinces of South Africa. The fecundity, body size and phenology of C. destructor were studied to provide a more informed basis for control programmes. No significant differences in fecundity were found between orchards (P > 0.05). However, fecundity varied significantly between female size-classes from the same orchard (P < 0.001). Female body-size differed significantly between orchards (P < 0.05) and was significantly positively correlated with fecundity both in 1997 and 1998. Different size-groups had varying oviposition periods, larger individuals having a longer oviposition period. No differences in egg fertility were found between orchards (P > 0.05). Ceroplustes destructor had one generation per year in the Western Cape Province, South Africa. Oviposition commences in mid November and continues until the end of December, with a few females ovipositing until mid January. The decline in population density of the second instar in February was followed by a steady increase in that of the third instar.
A survey of ants (Hymenoptera: Formicidae) that forage in vineyards in the Western Cape Province, South AfricaSource: African Entomology 8, pp 251 –260 (2000)More Less
This study was undertaken to establish which species of ants were associated with the mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), and which species were dominant in the main vine-growing areas of the Western Cape Province, South Africa. During 1998/99, 22 vineyards were surveyed in the StellenboschlPaarl, Little Karoo, Worcester, Swartland, Olifants River and Hex River Valley regions, using pitfall traps to sample epigaeic ants and tuna-bait traps to sample arboreal ants. Each vineyard was sampled intensively for two consecutive weeks shortly before harvest. Forty two species of ants were recorded during the survey. The most widely distributed ant species, which were potentially dominant and associated with mealybug outbreaks in vineyards in the Western Cape Province, were Anoplolepis custodiens (F. Smith), A. steingroeveri (Forel) and Linepithema humile (Mayrn). Crematogaster peringueyi Emery, Crematogaster sp. 2 and C. melanogaster Emery are three arboreal species potentially dominant in vines only. Dominance indices for Pheidole sp. 1 and Pheidole sp. 2 were low compared to the more aggressive Anoplolepis spp. and L. humile, indicating that the former two species were not economic significance. Edge effects occurred in five of the surveyed vineyards for three ant species. These edge effects indicate specific preferences of the ants for certain abiotic and microclimatic factors in vineyards, but could also be the result of interspecific competition.
Taxonomic affinities of Oeroparia Munro, Euryphalara Munro and Xenodorella Munro (Diptera: Tephritidae: Tephritinae)Author D.L. HancockSource: African Entomology 8, pp 261 –264 (2000)More Less
Deroparia reticulata (Munro), Euryphalara barnardi (Bezzi), E. extensa Munro, comb. n., E. sp. nr. extensa, E. mecistocephala (Munro) and Xenodorella mira Munro are considered to belong to a closely allied group of genera, the Euryphalara group, placed in the tribe Platensinini. The species occur mainly in Namibia and appear to be associated with Monechma (Acanthaceae).
Source: African Entomology 8, pp 261 –288 (2000)More Less
Pseudocloeon masai (Lugo-Ortiz & McCafferty), P. nadineae (Lugo-Ortiz & McCafferty) and P. quintum (Agnew) are junior subjective synonyms of P. glaucum (Agnew). Larvae of P. glaucum manifest a wide range of variation in mouthpart morphology, particularly with respect to the development of the distomedial process of segment 2 of the labial palps, body size, general body colour and abdominal colour pattern. Such variation is observed in different cohorts and populations, and explains why several names have been applied to the same species. Larvae of P. glaucum also have considerable ecological tolerance, accounting for the abundance and widespread distribution of the species in the Afrotropical Region. New records from Kenya, Lesotho, Namibia and Zimbabwe are provided.
Species composition and seasonal dynamics of lepidopterous stem borers on maize and elephant grass, Pennisetum purpureum (Moench) (Poaceae), at two forestmargin sites in CameroonSource: African Entomology 8, pp 265 –272 (2000)More Less
Lepidopterous stem borers were monitored on plots of maize, Zea mays, and elephant grass, Pennisetum purpureum (Moench), during two consecutive cropping seasons and the off-season at two forest margin locations, Nkolbisson and Minkomeyos, in Cameroon. Busseola fusca (Fuller), Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae) and Eldana saccharina Walker (Lepidoptera: Pyralidae) were found on both hosts. In addition, Cryptophlebia leucotreta (Meyrick) (Lepidoptera: Tortricidae) and Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) were collected from maize, and Poeonoma serrata (Hampson) (Lepidoptera: Noctuidae) from elephant grass. Busseola fusca was the most abundant species on both host plants. The numbers of eggs per square metre on different plant hosts was not significantly different, whereas numbers of larvae and pupae were 3-9 times higher on elephant grass than on maize. Analysis of numbers of B. fusca larvae according to size/age classes indicate that all sizes tended to be more abundant on elephant grass than on maize, but significant differences were found only during the second season at Minkomeyos, when densities were high. No significant differences were found between host plants for diapausing larvae and pupae. The implications for the possible function of the grass as a trap plant or reservoir for natural enemies in the management of B. fusca are discussed.