The effect of growing cowpeas mixed with either beans or maize on population densities of Megalurothrips sjostedti (Trybom) was investigated. Also investigated was the effect of varying the cropping densities of the host plants on the pest populations.

There was a significantly lower population of M. sjostedti in cowpea/maize, bean/maize, and cowpea/bean/maize mixed stands as compared with that in either cowpea/bean stands or monoculture stands of cowpeas and beans. Increasing the cropping densities of the host crops increased the abundance of the pest in non-maize based mixed stands, but this effect was not observed in the maize-based mixed stands.

The results indicate that with regard to infestation by M. sjostedti, the practice of mixed cropping beans with cowpeas confers no advantage to either crop with respect to attack by M. sjostedti. On the contrary, combining the two crops attracted infestation levels similar to those attracted by either crop grown in monoculture. But the inclusion of a non-host plant (maize) in the mixture, significantly reduces infestation.

Laboratory studies were carried out to determine factors which induce larval diapause in a Nigerian strain of Plodia interpunctella.

Larvae reared at constant temperatures of 20 or 30°C did not enter diapause. However, 13.3 and 37.7% respectively of larvae reared for 8 or 12 days (third or fourth instars) at 30°C and then transferred to 20°C entered diapause. Larvae transferred to 20°C immediately after hatch (first instar) and after 16 days (final instar) did not enter diapause. Developmental periods from egg-hatch to adult of diapausing individuals ranged from 136 to 151 days, while those of non-diapausing individuals reared at constant temperatures of 30 and 20°C ranged from 23 to 34 days and 60 to 72 days, respectively.

Different photoperiods did not induce diapause when reared at constant temperatures but exposure of larvae that experienced a drop in temperature from 30 to 20°C, at 4th instar stage to continuous light or to a long photoperiod (light 16 hr: dark 8 hr) caused a drop in the percentage larvae that diapaused.

Larvae reared at high larval density at 30°C did not enter diapause, and increased mortality was observed.

Using examples from surveys to collect natural enemies of the indigenous African sugarcane borer Eldana saccharina Walker throughout Africa, insight is given into what factors should be investigated should biological control of other indigenous African stemborers be considered. Indigenous host plant range, parts of indigenous and crop hosts attacked, types of natural enemies found in these different niches and natural enemy attack strategies are all important factors to consider when planning redistribution of indigenous natural enemies from one part of Africa to another. This knowledge is important when choosing the correct natural enemy for mass rearing and release into the affected crop, and can be used to manage the crop habitat, using the indigenous tritrophic systems identified, to increase crop diversity and thus effectiveness of indigenous natural enemies.

Several insect pests are associated with the sorghum crop, but essentially a few are considered key pests. These include shootfly, several species of stem borers, sorghum midge and a complex of head bugs. Other insect pests which are occasionally devastating and sporadic include leaf feeders and defoliators (Lepidoptera of various genera, locusts, grasshoppers, aphids, beetles, etc.) and also several species of head worms and head beetles. A list of 101 insect pests of sorghum occurring in Africa is presented.

Antixenosis resistance to Helicoverpa armigera (Lepidoptera: Noctuidae) was studied in 10 tomato accessions selected from a germplasm of 321 at Tamil Nadu, India, using free-choice and no-choice laboratory experiments. The foliage and fruits of two accessions, namely PT 4287 and Varushanadu Local were the least preferred for feeding in both tests. In the no-choice (confinement) test, Seijima Jeisei, Varushanadu Local and PT 4287 were the most preferred for oviposition, but had low egg hatch rates. In the free-choice test, these accessions were the least preferred for oviposition. The first and second instars preferred to feed on the foliage of 30- and 45-day-old plants, respectively than 60- and 75-day-old plants, whereas ovipositional preference was insignificant among the various plant ages.

An outbreak of the sugarcane whitefly (Neomaskellia andropogonis Corbett) recently occurred in sugarcane fields in Khuzestan Province of Iran. This pest sucks plant sap producing large amounts of honeydew. In Khuzestan Province, populations of all developmental stages increase from early August until late November. At this time, when sugarcane is at the ripening stage, nymphs suck the sap, and in cases of severe infestation, retard the growth of sugarcane plants. In this study, we investigated the biology of the pest on different cultivars of sugarcane and under different temperatures. Also, we conducted experiments to determine the damage caused by the pest in the field. Mean pre-adult developmental times were 24.09, 28.06, 27.27 and 26.64 days on CP69-1062, CP57-1062, CP48-103 and NCO-310 cultivars, respectively, and only female progeny were produced. Mean longevity of females on the four cultivars was 6, 8.49, 4.15 and 4.60 days, respectively. Adult females laid an average of 61.80, 58.80, 41.10 and 39.38 eggs on the four cultivars, respectively. Results show that the optimum temperature for development of different stages of N. andropogonis is 30±1°C during the day and 25±1°C at night, and at this temperature, egg and nymphal duration (including first, second, third instars and pupae) and adult longevity were 6.2, 17.0 and 7.6 days, respectively. Females of cultivar CP69-1062 laid an average of 50.09 eggs. Analysis of data on the quality of damage (including Brix, pol and refined sugar factors) shows that damage was inversely and significantly correlated with the number of infested leaves. Whitefly damage differed among cultivars; and, based on the quality of damage, early maturing cultivars were more susceptible to whitefly damage. We collected two parasitoid wasps from nymphs—Encarsia inaron (Walker) (Hym.: Aphelinidae) and Eretmocerus delhiensis Mani (Hym.: Aphelinidae). To the best of our knowledge, this is the first study to assess the biology, damage and natural enemies of N. andropogonis on sugarcane in Iran.

We evaluated an aqueous extract of Duranta repens L. in the laboratory against the tea red spider mite, Oligonychus coffeae Nietner, to determine its effect on adult mortality, viability of eggs, oviposition deterrence and repellent properties. We also evaluated the same extract in the field to determine its effect on mite populations. The direct spray method was used in the laboratory at concentrations of 2, 4, 6, 8 and 10 g/l. Mortality of O. coffeae was dependent on both concentration and time after application. Deposition of eggs by adult mites on treated leaf surfaces decreased and the viability of eggs was also reduced. Its bioefficacy was comparable to that of the commonly used commercial neem oil formulation (azadirachtin 0.03EC). In addition, different concentrations of the aqueous extract of D. repens also exhibited repellent properties against adult mites. In the field, the application of the aqueous extract of D. repens reduced the mite population and its bioefficacy was comparable to that of the synthetic pesticide Propargite 57 EC. No phytotoxic effect was observed when tea bushes were sprayed with different concentrations of D. repens. Tea samples were taint free. Treatment of plants with the extract did not affect the quality (appearance of liquor, flavour, taint and taste) of made tea. Availability and distribution of this plant in and around tea growing areas of Assam, along with its processing, and the possibility of including D. repens extracts in the current IPM programme are discussed.

Maruca vitrata (Fabricius, 1787) is a cryptic pantropical species of Lepidoptera that are comprised of two unique strains that inhabit the American continents (New World strain) and regions spanning from Africa through to Southeast Asia and Northern Australia (Old World strain). In this study, we de novo assembled the complete mitochondrial genome sequence of the New World legume pod borer, M. vitrata, from shotgun sequence data generated on an Illumina HiSeq 2000. Phylogenomic comparisons were made with other previously published mitochondrial genome sequences from crambid moths, including the Old World strain of M. vitrata. The 15,385 bp M. vitrata (New World) sequence has an 80.7% A+T content and encodes the 13 protein-coding, 2 ribosomal RNA and 22 transfer RNA genes in the typical orientation and arrangement of lepidopteran mitochondrial DNAs. Mitochondrial genome-wide comparison between the New and Old World strains of M. vitrata detected 476 polymorphic sites (4.23% nucleotide divergence) with an excess of synonymous substitution as a result of purifying selection. Furthermore, this level of sequence variation suggests that these strains diverged from ~1.83 to 2.12 million years ago, assuming a linear rate of short-term substitution. The de novo assemblies of mitochondrial genomes from next-generation sequencing (NGS) reads provide readily available data for similar comparative studies.

This paper reviews the work which had been done in Nigeria from 1911 to 1981 on several aspects of the biology of Zonocerus variegatus (L.), a variegated grasshopper pest of many food crops. The account covers recent advances in the areas of breeding biology, locomotory and migratory activities, morphometrics, feeding habits, parasitisation, and strategies for effective control of the grasshopper in Nigeria.

The leafminer, Liriomyza trifolii Burgess, a polyphagous agricultural pest, can attack crops at different stages of development; some are attacked at the beginning of the crop cycle and others at the end of the cycle. Experiments on the differential susceptibility of the bean Phaseolus vulgaris and the potato Solanum tuberosum plants were done to get some information about factors which influence host selection by the leafminer. The distribution and density of leaf trichomes, as well as the nutritional status of the host plants, were found to be important in host selection. High trichome density acts as a physical deterrent to Liriomyza flies, just as senescing primary bean leaves induce non-acceptability. When given a choice, flies prefer bean to potato leaf discs, though the latter possess less trichomes. Other factors (chemical attractants and some nutrient components) might therefore also be involved in the complex host selection behaviour of L. trifolii.

Bruchidius atrolineatus (Pic) is present in crops of Vigna unguiculata towards the end of the dry season at the beginning of September when pods start to form. Females lay many eggs on most available green pods. However, this oviposition behaviour results in an important egg mortality. During September, pods gradually reach maturity whilst new pods are formed. Females therefore have at their disposal a growing number of differently mature pods. Confronted with such a situation, B. atrolineatus females show an opportunist behaviour and lay most of their eggs on the most abundant stage, i.e. the most easily discovered stage (ripening green pods in mid-September or dry pods towards the end of September). However, they also lay eggs on other phenological stages no matter how abundant they are. B. atrolineatus females therefore show a certain behavioural plasticity enabling them to reproduce on all stages of pods whose maturity, chemistry and texture may differ. Larvae can develop either in maturing or dry seeds. The number of eggs laid from mid September is lower and lower whatever the phenological stage attacked. This decrease would be due to a reduction of the first generation adult bruchids and of the reproductive potential of females.

Callosobruchus maculatus appears in crops at the same time as B. atrolineatus, but oviposits preferentially on dry pods. Eggs are observed during the whole period of study, but the numbers laid are always low. With the increase in pod number, eggs are dispersed among the different substrates available. However, the average number of eggs laid on the pods remains constant. Despite the high mortality due to the oviposition behaviour of B. atrolineatus and to other factors (impact of hymenopterous parasitoids), these two bruchids cause important losses to seeds of V. unguiculata. Control methods against these pests should be envisaged in the field before harvesting.

Termites (Isoptera: Termidae), white grubs (Coleoptera: Scarabaeidae) and millipedes (Myriapoda: Odontopygidae) are the major groups of soil pests that are widespread and of economic importance in groundnut production in sub-Saharan Africa. Other Coleopteran pests such as wireworms (Elateridae) and false wireworms (Tenebrionidae) are found to be of occasional importance. Farmers' cultural practices such as improper application of organic manure, leaving crop residues in farms, delay in planting and harvesting, and abiotic factors such as rainfall and soil texture also influence soil pest occurrence and damage. Groundnut farmers in most parts of sub-Saharan Africa seldom apply effective control measures against soil pests. This paper reviews the major soil pests of groundnuts and their damage, and discusses adopted control practices and their applicability in integrated pest management (IPM) modules, with an emphasis on the use of resistant groundnut varieties, cultural practices, botanicals and minimal application of synthetic insecticides.

The biology of two African sweetpotato weevil species, Cylas puncticollis and C. brunneus (Fabricius) (Coleoptera: Apionidae), was studied in laboratory experiments carried out at 27 ± 1°C, 45 ± 5% RH, and a 12 h photophase. Cylas puncticollis females lived longer than C. brunneus (141 ± 10 and 92±12 days respectively), developed faster (egg to adult 20–28 days, and 32–41 days respectively) and had a lower oviposition rate (1.10 ± 0.04 and 1.53 ± 0.06 eggs per female per day respectively). The total egg production per female (average 101), sex ratio (1:1) and proportion of eggs surviving to adulthood (average 89%) were similar for both species. The intrinsic rate of increase was higher for C. puncticollis (0.553 per 10-day period compared to 0.521 for C. brunneus). Under field conditions C. brunneus will benefit from its higher oviposition rate during periods of favourable conditions for sweet potato weevils, like dry spells which expose tubers for egg laying. Cylas puncticollis will benefit from its longer longevity during less favourable conditions, as females can survive extended periods when no oviposition sites are available and then resume egg laying when conditions improve.

Two studies were undertaken to determine the species composition of the phlebotomine sandfly fauna in the Mokolo region, an endemic focus of cutaneous leishmaniasis in northern Cameroon. The preliminary survey conducted in July 1994 using sticky paper traps recorded 843 sandfly specimens, all belonging to the two genera of the Old World sandflies, Sergentomyia and Phlebotomits. The species included S. (Sergentomyia) schzvetzi, S. (Sergentomyia) antennata, S. (Parrotomyia) africana and P. (Phlebotomus) duboscqi: From January 1996 to December 1996, a total of 3241 sandflies were collected using sticky paper traps. In this sampling, six out of the total of eight species recorded were of the genus Sergentomyia. In addition to the species recorded in the preliminary study, S. (S.) bedfordi, S. (Grassomyia) squamipleuris, S. (Sintonius), clydei and P. (Anaphlebotomus) rodhaini were sampled in 1996. This is the first report of S. squamipleuris ir Cameroon. The implications of this study to the transmission of cutaneous leishmaniasis are discussed with particular reference to P. duboscqi, a known vector of the disease in the region.

Biochemical analysis of lakefly (chironomid/chaoborid mixtures and Povilla adusta samples) were conducted to determine their nutrient value and their potential as source of high quality nutrients in animal feeds. The results showed lakefly as rich in protein (62–67 g/100 g), fat (10 g/100 g) and ash (4–6 g/100 g). Moisture was low as was crude fibre. Povilla were richer in crude protein (67.4 g/100 g) and calcium (152 mg/100 g). The chironomid chaoborid mixture was however extremely rich in phosphorus (1.2 × 103 mg/100 g) and potassium (1.2 × 103 mg/100 g). Other trace elements were present in significant quantities as were niacine, thiamine and riboflavin. It is therefore deemed feasible to produce high quality nutrient concentrates from lakefly material for use in animal feeds. Further work Is however essential to determine lakefly digestibility and palatability and to ascertain suitable lakewide harvest techniques for the lakefly.

This paper, which discusses the current status of conventional insecticides in the management of stored product insect pests in the tropics, shows that insect infestation in stored products is high in the tropics and may lead to 100% damage in severe cases. Conventional insecticides used in their management, such as permethrin, lindane, pirimiphos-methyl, phostoxin, methyl bromide and io-dofenphos, and their methods of application are also discussed.

Methods of storing grains and other grain products are inadequate and in most cases reduce the efficacy of insecticides thereby enhancing the multiplication of the insects. The problems associated with insecticide usage in disinfesting stored products are highlighted and suggestions are made for their solutions.

The effects of egg clutch size on development and survivorship of the larger grain borer, Prostephanus truncatus (Horn) (Col.: Bostrichidae) on maize were measured in the laboratory using single grains of the white maize variety, TZSR-W, at 30 ± 2°C and 70 ± 5% RH. Varying numbers of P. truncatus eggs (1, 2, 4, 8, or 16) were introduced into a hole drilled into a single maize grain. Destructive sampling was used at regular intervals to obtain data on immature developmental parameters, the location of immatures within the grain and the weight and sex of any emerged adults. First instars fed mainly on the floury endosperm tissue whereas the second and third instars preferred the germ tissue. Mortality due to competition was highest in first instars. At high initial densities (> 4 per kernel), some P. truncatus larvae reduced competition by moving out of the grain. A maximum of 6 adults emerged from a single grain. The mean number of adults that emerged per grain for initial egg densities of 8 and 16 were 3.3 and 3.5, respectively. Prostephanus truncatus adult weight at emergence was not significantly influenced by initial egg density except in the case of clutch size 16. The sex ratio of emerged adults was also unaffected by competition, and was always 1:1. Complete developmental period within grains ranged between 28 and 32 days.

Studies were carried out from 1990 to 1993 to identify termite species associated with cocoa and coffee in Ghana. Ten genera/species, belonging to the families Termitidae and Rhinotermitidae, were recorded from cocoa and coffee trees aged from 6 to 36 months. The commonest was Ancistrotermes sp., followed by Amitermes sp., Microtermes subhyalinus, Microtermes sp. and Nasutitermes sp. Others were Macrotermes bellicosus, Pseudacanthotermes sp., Cubitermes sp., Schedorhinotermes putorius and Coptotermes sp. All species except M. bellicosus, Pseudacanthotermes sp. and Cubitermes sp. caused damage to cocoa and/or coffee. The shade tree, Gliricidia sp. was attacked by Pseudacanthotermes sp. whereas Macrotermes bellicosus and Cubitermes sp. were harmless. The relative abundance of these termites is discussed.

Several terpenoids and oils were screened for vapour toxicity and repellency against the termite, Odontotermes brunneus. In toxicity tests, knockdown time KT50 and KT90 values were derived at 5 mg/cm2. For repellency screening, a new experimental setup was designed and effective time ET50 and ET90 values were determined at 2 mg/cm2. Among the compounds screened, eucalyptus oil produced the fastest knockdown (KT50 24.8 min) while β-ionone was found to be the least effective (KT50 536.0 min). Terpeneol (anhydrous) afforded maximum persistence of 338.0 min, whereas the least persistence was obtained from linalool (78.9 min) which prevented 50% of the population from crossing over the treated barrier (ET50).

The Nocardiaceae family members are symbiont bacteria from triatomine insects. The aim of this study was to detect the presence of Nocardiaceae family bacteria in Rhodnius ecuadoriensis intestinal bacterial flora. Bacterial colonies were isolated from the intestinal content from all insects; they had pink or coral pink pigmentation corresponding to Gram-positive coccobacilli. These isolates' biochemical identification by catalase and urease tests and the assimilation of different carbon sources led to Rhodococcus rhodnii being identified. This result was confirmed by 16S ribosomal ribonucleic acid gene sequencing. Additional studies are required to establish the symbiont role of this bacterium in R. ecuadoriensis as it has in Rhodnius prolixus.