Responses to colour and host odour cues in three cereal pest species, in the context of ecology and control

Many insects show a greater attraction to multimodal cues, e.g. odour and colour combined, than to either cue alone. Despite the potential to apply the knowledge to improve control strategies, studies of multiple stimuli have not been undertaken for stored product pest insects. We tested orientation towards a food odour (crushed white maize) in combination with a colour cue (coloured paper with different surface spectral reflectance properties) in three storage pest beetle species, using motion tracking to monitor their behaviour. While the maize weevil, Sitophilus zeamais (Motsch.), showed attraction to both odour and colour stimuli, particularly to both cues in combination, this was not observed in the bostrichid pests Rhyzopertha dominica (F.) (lesser grain borer) or Prostephanus truncatus (Horn) (larger grain borer). The yellow stimulus was particularly attractive to S. zeamais, and control experiments showed that this was neither a result of the insects moving towards darker-coloured areas of the arena, nor their being repelled by optical brighteners in white paper. Visual stimuli may play a role in location of host material by S. zeamais, and can be used to inform trap design for the control or monitoring of maize weevils. The lack of visual responses by the two grain borers is likely to relate to their different host-seeking behaviours and ecological background, which should be taken into account when devising control methods

Antimicrobial Properties and Phytochemical Analysis of Methanolic Extracts of Aframomum Melegueta and Zingiber Officinale on Fungal Diseases of Tomato Fruit

The antimicrobial properties of methanolic extracts of Aframomum melegueta seeds and rhizomes of Zingiber officinale were investigated on Helminthosporium solani, Aspergillus niger, Penicillium digitatum and Mucor piriformis isolated from tomato. This research was undertaken to control the growth of these rot fungi in vitro. Extracts at various concentrations ranging from 0-30% were separately added to PDA media. The plates were inoculated separately with the fungal isolates. Effects of these extracts on mycelial growth of the fungi were highly significant (P < 0.05) for all treatments. Z. officinale extract at 25% and A. melegueta at 30% concentration gave complete inhibition. Phytochemical analyses of extracts revealed the presence of tannins, phlobatannins, steroids, tarpenes, saponins, flavonoids and alkaloids. The presence of these compounds supports the use of the extracts as antimicrobial agents which can prolong the shelf–life of fresh tomato fruits. Keywords: Antimicrobial properties, Extract, Phytochemicals, Aframomum melegueta, Zingiber officinale

Field infestation of three maize (Zea mays l.) genotypes by lepidopterous stem borers in Makurdi, Nigeria

Two field experiments were conducted in July and August 2004 to determine the effect of date of planting and rate of application of carbofuran (Furadan 3G) on damage by stem borers to flint, sweet and pop maize (Zea mays L)genotypes. Each experiment was laid out in a randomized complete block design (RCBD), with a spilt plot arrangement of treatment, replicated four times. Results from July 2004  cropping season showed significant interactions of maize genotypes and rate of application of carbofuran in percentage bored stem and number of borer cavity. However, borer population density and damage were effectively reduced by carbofuran application at the rate of 1.5 Kg a. i/ha. In August planting, the results showed that borer infestation was approximately five times higher in the control plots than treated plots. Carbofuran at the rate of 1.5 Kg ai/ha could be used to control stem borer population effectively in all the three genotypes, to obtain higher grain yield.KEY WORDS: Stem Borers, Damage, Zea mays, Planting Date, Carbofuran

Implementation of an RF based wireless automated energy metering and billing system

There are certain electrical power losses which have been affecting the availability of electrical power in developing countries. The rate of non-technical losses in developing countries is quite high which ranges from electricity theft and non-payment of bills. Therefore, this paper is aimed at the design and implementation of a Radio Frequency (RF) based wireless automatic energy meter reading system. This system uses a digital energy meter consisting of current and voltage sensors, analog to digital converters, a microcontroller and a Liquid Crystal Display (LCD) unit. The Base Station Wireless interfaced device was able to perform the desired interfacing function between the energy meter and the base station. Bills and reports were generated by the PC software and the outputs were found to be accurate. This system does not only reduce the cost of labour but also increases meter reading accuracy

Response of Potential Stored Grain Insect Pests to BFL 225 Multi-Attractant Lure in Commercial Warehouses.

Farmers generally store their harvested products to ensure a continuous food supply for their household, provide seed for subsequent crops and farm, and as a source of income because it allows farmers to sell the products for cash or to exchange it for other products. But the introduction of new crop varieties, satisfying primarily an increased yield, has led to a contemporary selection of plants susceptible to infestation by insects, due to a loss of resistance to insect attack. Studies were conducted to determine the efficacy of traps baited with the kairomone BFL 225 multi-attractant lure for the detection and monitoring of storage insect pests into commercial warehouses in southern Nigeria for ten months. This trapping experiment demonstrated that floor traps baited with BFL 225 lure significantly (P< 0.001) captured insects compared to the unbaited (control). The predominant insects captured include Sitophilus spp., Plodia interpunctella, Tribolium castaneum, Callosobruchus maculatus, Alphitobius laevigatus and Rhyzopertha dominica. The implication of his study is that BFL 225 could be utilized as a part of integrated pest management strategies for early detection of potential insect pests migrating into stored grain warehouses in tropical Africa. Keywords: Baited traps, storage pests, kairomone, monitoring, warehouses

Behavioural and olfactory responses of Sitophilus zeamais (Coleoptera: Curculionidae) to Aframomum melegueta and Zingiber officinale oleoresins.

The oleoresins extracted from the seeds of alligator pepper, Aframomum melegueta and ginger, Zingiber officinale rhizome using methanol, was evaluated for bioactivity against the maize weevil, Sitophilus zeamais in the laboratory. Using a 4-arm olfactometer, solutions of the oleoresins at a concentration of 1 mg/ml exhibited significant olfactory repellent activity against male and female S. zeamais when tested alone, and in combination with maize seeds. These findings provide a scientific basis for the observed repellent properties of the oleoresins and demonstrate the need for their development in stored product pest protection in Africa where these plants are readily available.KEYWORDS: Oleoresin, Aframomum melegueta, Zingiber officinale, Sitophilus zeamais, Olfactometer

Evaluation of the Insecticidal and Deterrence Properties of Pepper Fruit, Dennetia tripetala (G. Baker) and Ginger Zingiber officinale Roscoe against Maize Weevil Sitophilus zeamais (Motsch.)

Laboratory studies were conducted to evaluate the insecticidal and deterrent properties of pepper fruits (Dennetia tripetala) and ginger (Zangiber officinale) against maize weevil Sitophilus zeamais. One hundred grams of maize were weighed into 500ml kilner jar and treated with 0%, 1%, 5% and 10% powders each of D. tripetala and Z. officinale in a 4x4 factorial combinations on weight by weight (w/w) basis. The experiments were laid out in a Complete Randomized Design (CRD) and replicated four times. Results showed significant (P<0.05) percentage mean adult mortality of 13.34, 15.34 and 16.33 post treatment with D. tripetala and 11.33, 14.33 and 18.7 post treatment with Z. officinale at 10% after 24, 48 and 72h respectively over other levels. At 5%, the percentage adult mortality was significantly higher than at 1% and the control after 72 hours post exposure. Significantly (P<0.05) higher percentage adult mortality was also observed in the 10% combinations of the tested plant products of 4, 5.33 and 5.67 after 24, 48 and 72 hours of storage for D. tripetala and Z. officinale respectively. Also, significantly (P<0.05) higher adult mortality 1065.66 and 1070.33 were observed on Z. officinale and D. tripetala treated seeds after 10 weeks storage period. The 10% treatment combination of the tested powders also showed significantly (P<0.05) higher adult mortality, which was however, not significantly different(P>0.05)  from the 10% D. tripetala and 5% Z. officinale and also10% Z. officinale and 5% D. tripetala. Significantly (P<0.05) higher percentage adult deterrence of 46.53% was obtained when 10% D. tripetala was applied compared to the other levels. Significant (P<0.05) reduction in the number of adults that emerged was observed when treatment concentrations increases. The studies showed that extracts of Z. officinale and D. tripetala can be used effectively singly or in combination as grain protectants in stored maize for the management of S. zeamais. Keywords: Dennetia tripetala, Sitophilus zeamais, mortality, deterrence, protectant

Shades of yellow: interactive effects of visual and odour cues in a pest beetle

Background: The visual ecology of pest insects is poorly studied compared to the role of odour cues in determining their behaviour. Furthermore, the combined effects of both odour and vision on insect orientation are frequently ignored, but could impact behavioural responses. Methods: A locomotion compensator was used to evaluate use of different visual stimuli by a major coleopteran pest of stored grains (Sitophilus zeamais), with and without the presence of host odours (known to be attractive to this species) in an open-loop setup. Results: Some visual stimuli – in particular, one shade of yellow, solid black and high contrast black-against-white stimuli – elicited positive orientation behaviour from the beetles in the absence of odour stimuli. When host odours were also present, at 90° to the source of the visual stimulus, the beetles presented with yellow and vertical black-against-white grating patterns changed their walking course and typically adopted a path intermediate between the two stimuli. The beetles presented with a solid black-on-white target continued to orient more strongly towards the visual than the odour stimulus. Discussion: Visual stimuli can strongly influence orientation behaviour, even in species where use of visual cues is sometimes assumed to be unimportant, while the outcomes from exposure to multimodal stimuli are unpredictable and need to be determined under differing conditions. The importance of the two modalities of stimulus (visual and olfactory) in food location is likely to depend upon relative stimulus intensity and motivational state of the insect

Odour-mediated orientation of beetles is influenced by age, sex and morph

The behaviour of insects is dictated by a combination of factors and may vary considerably between individuals, but small insects are often considered en masse and thus these differences can be overlooked. For example, the cowpea bruchid Callosobruchus maculatus F. exists naturally in two adult forms: the active (flight) form for dispersal, and the inactive (flightless), more fecund but shorter-lived form. Given that these morphs show dissimilar biology, it is possible that they differ in odour-mediated orientation and yet studies of this species frequently neglect to distinguish morph type, or are carried out only on the inactive morph. Along with sex and age of individual, adult morph could be an important variable determining the biology of this and similar species, informing studies on evolution, ecology and pest management. We used an olfactometer with motion-tracking to investigate whether the olfactory behaviour and orientation of C. maculatus towards infested and uninfested cowpeas and a plant-derived repellent compound, methyl salicylate, differed between morphs or sexes. We found significant differences between the behaviour of male and female beetles and beetles of different ages, as well as interactive effects of sex, morph and age, in response to both host and repellent odours. This study demonstrates that behavioural experiments on insects should control for sex and age, while also considering differences between adult morphs where present in insect species. This finding has broad implications for fundamental entomological research, particularly when exploring the relationships between physiology, behaviour and evolutionary biology, and the application of crop protection strategies