Borer Prostephanus Truncatus Research Articles

The use of Beauveria bassiana for the control of the larger grain borer, Prostephanus truncatus, in stored maize: Semi-field trials in Ghana

Laboratory research in Ghana demonstrated the effectiveness of an isolate of Beauveria bassiana (IMI 389521) from the United Kingdom against the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), a major pest of stored maize. The minimum effective concentration, following artificial infestation trials on maize, was between 109 and 1010 cfu/kg maize. Before moving out to village-level control, a major requirement was to determine if the product could effect control in artificially infested maize held under real environmental conditions in several locations in Ghana. Therefore, this study investigated the efficacy of formulated conidia of B. bassiana, IMI 389521, at two concentrations (1 × 109 and 3.16 × 109 cfu/kg maize) to control P. truncatus on stored maize kernels under semi-field conditions in Ghana. Maize (‘Obatanpa’ cultivar) kernels were treated with the formulated B. bassiana product and stored in polypropylene woven bags in cribs in Southern Ghana. After 24 h, one hundred adults of P. truncatus were placed into each bag containing the treated maize. Mortality and the percent of weight loss of kernels were assessed every two weeks for three months. The semi-field trials revealed the possibility of successfully controlling adult P. truncatus on maize kernels treated with B. bassiana at 3.16 × 109 cfu/kg maize. However, due to the minimal protection of kernels after four weeks, re-treating maize kernels after this period is recommended to ensure maximum protection during prolonged storage.

Beetle-robot hybrid interaction: sex, lateralization and mating experience modulate behavioural responses to robotic cues in the larger grain borer Prostephanus truncatus (Horn)

Ethorobotics, a new fascinating field of biorobotics, proposes the use of robotic replicas as an advanced method for investigating animal behaviour. This novel research approach can also encourage the development of advanced bioinspired robots. In the present study, we investigated the pushing behaviour, a particular display occurring in several beetle species, such as the larger grain borer, Prostephanus truncatus, during both male-female and male-male contexts. We developed a robotic apparatus actuating female and male-mimicking dummies to study if sex, mating experience and asymmetries of robotic cues can modulate the escalation of pushing behaviour. Results showed that the time needed by P. truncatus to react to female-smelling biomimetic dummies was chiefly affected by their mating experience and the dummy odour. This was likely due to reduce waste of costly sperm in mated males during the subsequent sexual interactions. The pushing behaviour was performed longer and with a higher number of acts when virgin females were approached from their right side. More and longer pushing acts were noted when virgin males were approached from their left side. Dedicated neural circuits would likely act in opposite direction in females and males producing population-level lateralized sensory-motor displays, which may be evolved to promote male approaches from the left side of females, thus improving short-distance sex recognition. Overall, this study provides new insights on the behavioural ecology of stored-product beetles, as well as on self-organization and decentralized decision making that can be exploited to develop bioinspired algorithms for task optimization, involving real-world scenarios.

Reproductive performance of the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on three different food hosts

The reproductive performance, damage and weight loss of the Larger Grain Borer (LGB), Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on three food hosts namely cassava (TMS 30572, TME 419 and TMS98/0505), maize (SUWAN-1-SR-Y, BR 9943-DMR-SR and 2009 TZEWDT STR) and wood (Albizia glaberrima, Gmelina arborea and Tectona grandis) were investigated. Samples of 100g of the food host were weighed in four replicates into 250ml Kilner® jar and infested with 10 pairs of 1-5 day old LGB. The developmental period of LGB on each of the food host was noted and recorded. Similarly, weight loss and weight of damaged grains was determined as basis for determining the susceptibility of the food hosts to LGB infestation. Proximate composition of infested and un- infested food hosts of LGB were determined following the analytical procedures. Maize was the most preferred host, followed by cassava as indicated by the high number of adult LGB and grain damage recorded on them. The development of LGB was completed on all maize and cassava varieties but not on any of the wood species examined. Percent damage, weight loss, and percent dust were significantly (P<0.05) different among the food hosts. The mean percent damage (79.0), percent weight loss (57.0) and percent dust (25.0) recorded in cassava variety-TMS30572 was significantly (p<0.05) higher than on other food hosts. No weight loss was recorded on T. grandis. This study revealed the ability of P. truncatus to breed and feed on the maize and cassava varieties with no evidence of breeding on the three wood species. Carbohydrate contents were higher in the most preferred food host, maize (70.91) and less preferred food, cassava (82.02) than non-preferred wood species (13.56), indicating that carbohydrate was an essential component in most preferred food. Infestation of LGB caused significant reduction (P<0.05) in the nutritional component of the food hosts. This study showed that LGB still remains an economically important insect pest of maize and cassava. Considering the importance of these two crops to the livelihood of smallholder farmers, appropriate monitoring and control measures should therefore be put in place to safe guard maize and cassava from the ravages of this pest for the attendant enhancement of food security in Nigeria.

Physical factors in the hermetic SuperGrainBag® and effect on the larger grain borer [Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)] and aflatoxin production by Aspergillus flavus during the storage of ‘Obatanpa’ maize (Zea mays L.) variety

Controlling invasive pests and aflatoxin production by moulds in stored grains is a global challenge to food security and public health, particularly in Africa. Food storage systems are designed to provide constraints to spoilage organisms by presenting mechanical barrier or unfavourable atmospheric conditions to their growth and productivity. This study examined the physical factors generated in hermetic SuperGrainBags® during the storage of ‘Obatanpa’ variety of maize (Zea mays L.) and the effect on growth of the larger grain borer Prostephanus truncatus (Horn) and aflatoxin contamination by Aspergillus flavus. Cultured P. truncatus or A. flavus was introduced into 1.5 kg of the dried maize and stored in either hermetic SuperGrainBags® or non-hermetic polypropylene bags. The hermetic conditions elicited an increase in the interstitial temperature (ca. 27 °C) but a decrease in the relative humidity (<70%), oxygen concentration (<6.4%) and the grain moisture content (<13.7%), the combined effects of which inhibited growth of the insects and aflatoxin production by the moulds. Total mortality of P. truncatus occurred after 52 d of storage in the SuperGrainBags® while aflatoxins concentration remained within safe limits for human consumption. In contrast, there was proliferous growth of P. truncatus and significant increase in aflatoxin concentration to lethargic levels within the polypropylene bags where temperature, relative humidity and grain moisture increased significantly. Accordingly, grain damage and weight loss percentages were significantly high in the polypropylene bags while that in the SuperGrainBags® were negligible. Altogether, the SuperGrainBags® better preserved the maize grain quality and safeguarded it against health risks than the polypropylene bags.

Beauveria bassiana affects immature stage development of Prostephanus truncatus (Coleoptera: bostrichidae) in stored maize

ABSTRACTRecent research in Ghana has demonstrated the effectiveness of an isolate of B. bassiana, sensu lato (IMI 389521) from the U.K. against the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), a major pest of stored maize. To determine whether this isolate is effective on immature stages of P. truncatus, a laboratory study of the response of immature stages (egg, larvae and pupae) of P. truncatus in maize grains to two concentrations (1 × 109 and 3.16 × 109 cfu/kg maize) of B. bassiana, IMI 389521 formulated with Entostat™ and kaolinite was undertaken. Adult emergence, per cent survival of adults that emerged and the number of larvae in each immature stage were assessed after 45 days. Apart from the egg experiment, higher numbers of adults emerged in grains containing larvae and pupae treated with B. bassiana product compared to the untreated maize control. This notwithstanding, survival of emerged adults of P. truncatus was greatly reduced in B. bassiana treatments (<10%) compared with 75–95% in the controls. Surface treatment with B. bassiana on pre-infested maize showed a significant effect on the developmental biology of P. truncatus in Ghana.

Comparison of the processing and quality of tortillas produced from larger grain borer Prostephanus truncatus (Horn.) resistant and susceptible maize genotypes

The aim of this research was to compare the processing and quality of tortillas produced from two kinds of larger grain borer (LGB) Prostephanus truncatus (Horn.) damaged kernels: resistant (IRM) and susceptible (ISM) genotypes. The damaged LGB kernels had significant lower test weight, 1000 kernel weigh and density. The ISM kernels were more negatively affected by insects compared with the IRM counterpart. A significant reduction of 5% in starch was observed in IRM kernels but not in ISM counterparts. Flour acidity and protein increased 8-fold and 5%, respectively parallel to an augmentation of weight grain losses whereas the crude fat content significantly reduced by 29%. Insect damage enhanced the penetration of the hot lime solution into the starchy endosperm. Insect infested kernels which lost 10% and 20% of their weight required 34% and 42% less lime-cooking time compared to sound kernels. The 10% and 20% insect-damaged kernels lost 15 and 23% of their solids during storage and tortilla processing, respectively. Finally, LGB damaged kernels reduced substantially the tortilla quality in terms of color.

Effects of insect population density and storage time on grain damage and weight loss in maize due to the maize weevil Sitophilus zeamais and the larger grain borer Prostephanus truncatus

In the period 2007 to 2010, at localities Backi Maglic and Krivaja studies of weed seedbank were performed under soybean crop. Results showed that weed seed separated at Backi Maglic in all years dominated in the top soil layer, while the lowest quantities were separated from the deepest layer, and that number of weeds declined annually. At Krivaja, the lowest weed seed stocks were found in the top layer, and the highest in the deepest layer. At this locality, number of weed seeds kept rising from season to season, which was the consequence of application of different cultural practices. Key words: Soybean, weed seedbank, Amaranthus retroflexus L., Chenopodium album L.,Datura stramonium L.

Resistance of three-way cross experimental maize hybrids to post-harvest insect pests, the larger grain borer ( Prostephanus truncatus) and maize weevil ( Sitophilus zeamais)

The larger grain borer Prostephanus truncatus Horn and the maize weevil Sitophilus zeamais Motschulsky are important pests of stored maize in the tropics, particularly where maize is stored on-farm with little control of moisture content and without use of pesticides. This study was undertaken to determine level of resistance among new experimental maize hybrids against P. truncatus and S. zeamais. Out of the 54 experimental hybrids tested, eight hybrids were resistant, six were susceptible and the remaining 40 hybrids were moderately resistant. Five hybrids showed considerable reduction in losses for both P. truncatus and S. zeamais (CKPH08013, CKPH08021, CKPH08003, CKPH08004 and CKPH08009), suggesting that they contained genes that confer resistance to the two pests. Low grain weight loss, powder production and low insect multiplication on resistant grains reduce the negative impact of the two beetle pests. Therefore, host plant resistance can be used as a vital component of an integrated pest management strategy against P. truncatus and S. zeamais.

Phylogeographic structure of Teretrius nigrescens (Coleoptera: Histeridae) predator of the invasive post harvest pest Prostephanus truncatus (Coleoptera: Bostrichidae)

The invasive larger grain borer Prostephanus truncatus (Horn) is the most important pest of farm-stored maize in Africa. It was introduced into the continent from Mesoamerica in the late 1970s and by 2008 had spread to at least 18 countries. Classical biological control using two populations of the predator Teretrius nigrescens Lewis achieved long-term and cost effective control in warm-humid areas, but not in cool and hot-dry zones. The present study investigated the phylogenetic relationships between geographical populations of the predator. Ten populations of T. nigrescens were studied using randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR), sequence analysis of mitochondrial Cytochrme oxydase 1 (mtCOI) gene and ribosomal internally transcribed spacers (ITS) 1, 5.8S and ITS2. The mtCOI variation revealed two clades associated with geographical regions in Central America. It also reveals a significant isolation by distance between populations and considerable genetic shifts in laboratory rearing. RAPD-PCR did not reveal any potential SCAR diagnostic markers. The ITS variation mainly involved insertions and deletions of simple sequence repeats even within individuals. This study reveals the existence of two different mitochondrial lineages of the predator, associated with the geographical origin of populations distinguishable by fixed mutations on the mtCOI gene. The populations of T. nigrescens released in Africa belonged to two different clades from Meso America, namely south (released in West Africa) and north (released in eastern Africa). However, more polymorphic markers are required to clarify the observations in demographic time scales.

Evaluation of damage of some food commodities by larger grain borer–Prostephanus truncatus (Horn) {Coleoptera: Bostrichidae} and microbial composition of frass induced by the insect

The microbial composition of the frass from maize (Zea mays) grains and seven dried root and tuber crops (R&TC) infested by Prostephanus truncatus were evaluated. Five cubes (6 cm3) of each R&TC as well as 100 g of maize grains were separately infested with 15 pairs of 1–2 day old adult LGB in 250 cm3 sized Kilner jars and incubated for 90 days at 28 ± 1°C and 79–82% RH. At 90 days post-infestation, the microbiological assay of frass from the commodities was performed. The results indicated the presence of 10 bacterial species, namely Bacillus cereus, B. macerans, Proteus mirabilis, P. morganic, P. rettgeri, Proteus sp., Pseud geniculatum, Pseud fragii, Pseud putela, Serratia marcences and six fungal species, namely Aspergillus niger, A. tamari, A. parasiticus, A. ochraceus, Fusarium compacticum and F. oxysporum. Infested cubes of M. esculenta have the highest population of adult LGB (168.3) and frass from its damaged cubes had the highest mean bacterial count of 30.0 × 107 colony forming units (CFU) and it was significantly (P < 0.05) higher than LGB infestation and bacterial infection of other R&TC. The bacterial count from the damaged commodities correlated positively and significantly (P < 0.05) with weight of frass, percentage damage and percentage weight loss. The results revealed that frass from the LGB-infested and damaged commodities were infected by bacteria and fungi. Maize grains and dried R&TC should therefore be protected from LGB infestation to avoid quantity reduction and microbial infection.

The flight activity of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Teretrius nigrescens Lewis (Coleoptera: Histeridae) in Kenya

The invasive storage pest, the larger grain borer (LGB) Prostephanus truncatus (Horn), was introduced into the maize-deficit, semi-arid areas of the eastern region in Kenya in the early 1980s. In spite of containment efforts and the introduction of the predator Teretrius nigrescens Lewis from Mexico, LGB has spread to the main maize production zone in western Kenya during the past five years. The present work presents results from a 28-month monitoring effort of LGB and its predator, using pheromone traps at five locations along an east-west transect across Kenya. LGB occurred in all regions with highest trap catches in the high potential maize production zones in Western Kenya. T. nigrescens had not spread to western Kenya and trap catches were very low and mostly zero in Eastern Kenya, even in the area where it was released during the 1990s, suggesting that it became locally extinct after initial establishment. LGB flight activity was closely related to relative humidity, temperature and vapour pressure deficit. A model based on climatic factors accurately predicted seasonal trends of LGB flight behaviour in Kakamega and Mombasa but not in Kitale and Thika. It was concluded that models that rely on the direct effect of climate cannot predict LGB flight accurately enough to allow assessment of the impact of T. nigrescens on a regional basis. It is suggested that other factors such as the availability of stored grain and thus the indirect effect of climate via enhanced or reduced crop production play a major role in the flight activity of LGB and T. nigrescens.

Dynamics of infestation and losses of stored maize due to the larger grain borer (Prostephanus truncatus Horn) and maize weevils (Sitophilus zeamais Motschulsky)

The dynamics of infestation and losses of stored maize due to the larger grain borer (Prostephanus truncatus Horn) and maize weevils (Sitophilus zeamais Motschulsky) were investigated in Tanzania. In single species populations, significantly higher maize damage (P ≤ 0.05) was caused by P. truncatus (23.3%) compared to S. zeamais (6.4%). Weight losses caused by P. truncatus were higher (12.7%) than for S. zeamais (6.7%) under similar conditions. A higher proportion of P. truncatus in the initial infestation population led to significantly higher (≤0.05) maize damage compared to equal or higher proportions of S. zeamais. Irrespective of the initial number of S. zeamais, population size increased to levels higher than for P. truncatus. Maize losses in unimproved storage structures were >80% compared to <2.5% in improved structures under natural infestation. Inter-specific competition appeared to influence the dynamics of infestation, damage levels and weight losses. The first two months of storage were critical for damaging insect populations to build up.

Propolis Production by Honey Bee Apis Mellifera (hymenoptera: Apidae) and its Potential for the Management of the Larger Grain Borer Prostephanus Truncatus (Horn) (coleoptera: Bostrichidae) On Maize Grains

Propolis Production by Honey BeeApis Mellifera(hymenoptera: Apidae) and its Potential for the Management of the Larger Grain BorerProstephanus Truncatus(Horn) (coleoptera: Bostrichidae) On Maize GrainsThe aim of the study was to evaluate a possibility of propolis production by honey beeApis mellifera(Horn) (Hymenoptera: Apidae) and its potential for the management of the larger grain borer (LGB)Prostephanus truncatus(Horn) (Coleoptera: Bostrichidae) on maize grains. Bee propolis was collected from hives kept on the field for twelve months; they were thereafter diluted with ethanol to obtain 5%, 10%, 15% and 20% concentrations. 5 ml each of the concentrations was applied to 150 g clean maize grains infested with 10 pairs of 1-5 days old LGB in 250 cm3Kilner jars. The control jars were treated with ethanol. At 90 days post-infestation, data were collected on percentage of weight loss, percentage of grain damage, weight of frass generated (g), number of pupae, larvae and adult LGB. The results indicated that monthly propolis yield was significantly (p &lt; 0.05) lower in the period of honey flow (December-March) relative to other periods. Propolis at all the concentrations tested reduced the population of LGB in propolis-treated maize grains relative to non-propolis treated-ones. The highest effects of propolis was shown at the highest concentration of 20% and it was significantly (p &lt; 0.05) different from its effects at other concentrations. Bee propolis may be integrated with other ecological friendly control methods to manage LGB infestation in maize.

Suitability of sorghum grain for the development of the larger grain borer &lt;i&gt;Prostephanus truncatus&lt;/i&gt; (horn) (Coleoptera: bostrichidae)

Laboratory studies were carried out to determine the development of the Larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on sorghum grain. Substrate suitability, susceptibility and preference tests were conducted. Tests were conducted using P. truncatus on 3 sorghum (2 high-yield [Framida and Naga-White] and 1 native [mankaraga]) and 1 maize (native) cultivars. The beetle successfully completed its life cycle on sorghum grain, when stored as whole grain or finely ground grain flour. However, the beetle failed to develop on sorghum grain, when stored as coarsely ground grain. Mean development period of the grain borer was 36 to 60 days and differed with substrate type and grain cultivar. Mean number of first generation (F1) adult beetles recovered ranged from 1.51 to 13.6 individuals. In a similar manner, the mean weight of beetles produced ranged from 1.70 to 3.02 mg. Furthermore, P. truncatus showed higher preference for the high-yield improved sorghum cultivars (Framida & Naga-White) than the native one (Mankaraga). These high-yield improved sorghum cultivars were also more susceptible to attack by the stem borer. These cultivars have relatively soft pericarp and endosperm texture which offered low resistance to the boring and tunneling activities of these beetles. This indicates that in the absence of its most preferred host (maize), P. truncatus can subsist on sorghum grain. Thus sorghum grain can serve as a reservoir for P. truncatus. These findings should be exploited when designing biological control programmes in sorghum growing regions of sub-Saharan Africa. Keywords: Prostephanus truncatus, sorghum grain, substrate suitability, susceptibility index, grain preference, biological control

Efficacy of neem oil and neemazal against the larger grain borer, prostephanus truncates (Horn) in stored maize

The biological activity of neem oil and Neemazal on adult and immature stages of the larger grain borer Prostephanus truncatus , as well as on its F1 progeny was assessed in stored maize in the laboratory. Repellency and persistency effects of the treatments in grain to the insect, as well as the effect of the treatments on grain damage, were also determined. Neemazal was more toxic to P. truncatus than neem oil. The highest dosage of 0.8ml/200g grain killed 100% adult P. truncatus after 72 h exposure but the same dosage of neem oil resulted in 70% mortality after 96h. The products also caused significant (p P. truncatus in stored maize.

Assessment for fungal, mycotoxin and insect spoilage in maize stored for human consumption in Zambia

AbstractBACKGROUND: Maize constitutes the main staple food and most important crop grown in Zambia. However, maize incurs considerable losses both in field and storage due to pathogens and insects. Some of the pathogens and resultant mycotoxins reduce the nutritional quality of the product. Mycotoxins are toxigenic fungal compounds that can cause cancer and suppress growth. In spite of this health hazard, there has been very little research to document their occurrence. Maize grains stored for human consumption were sampled from different agro‐ecosystems (forest, valley and plateau areas) of three agroecological zones (high, mid and low altitude).RESULTS: Several fungal genera were recovered among which Aspergillus flavus, A. niger, Fusarium verticillioides, F. solani, Rhizopus stolonifer and Penicillium spp. were prevalent. The weevil Sitophilus zeamais and the larger grain borer Prostephanus truncatus were the most damaging. Enzyme‐linked immunosorbent assay (ELISA) tests yielded fumonisins and aflatoxins ranging between 0.02 and 21.44 ppm, and 0.7 and 108.39 ppb in 96.4% and 21.4% of samples, respectively. Fumonisin was more pronounced in villages in forest areas whereas aflatoxin was highest in valley and forest areas in Zone II.CONCLUSION: Strategic interventions to curtail fungal, mycotoxin and insect contamination should be directed towards improved agronomic and post‐harvest practices of maize from fields to consumers. Copyright © 2009 Society of Chemical Industry

Isolation and characterization of microsatellite markers fromTeretrius nigrescensLewis (Coleoptera: Histeridae), predator of the storage pestProstephanus truncatus(Horn) (Coleoptera: Bostrichidae)

Teretrius nigrescens is a predator of the larger grain borer (LGB) Prostephanus truncatus, an invasive post-harvest pest in Africa. We describe the isolation and characterization of 24 novel polymorphic microsatellite markers and their testing on a population from Honduras. Alleles per locus ranged between 2 and 12, and observed heterozygosity between 0.037 and 0.646. Six loci deviated significantly from Hardy-Weinberg equilibrium and showed evidence of null alleles. These markers will be useful for studies of the predator's population structure and characterizing populations for control of LGB.

First report on occurrence of the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in Senegal

In Africa the larger grain borer, Prostephanus truncatus (Horn) (Coleoptera : Bostrichidae) (Fig. 1) is a serious pest of stored commodities mainly of stored maize, dried cassava roots and to a lesser extent yam chips. This bostrichid pest of meso-American origin was accidentally introduced into Africa some 30 years ago and started to spread over the continent from two geographically disparate points. The first recognized outbreaks of P. truncatus were reported in the late 1970s from East Africa, in the Tabora, Shinyanga and Mwanza regions of western Tanzania. Subsequently P. truncatus was found to be established in Togo, West Africa, in 1984 (Farrell & Schulten 2002). From there the pest gradually spread in the neighboring countries of Benin, Burkina Faso, Niger, Nigeria, reaching Guinea Conakry in 1988 and Guinea Bissau in 1998 (Aman et al. 2007).

Control de Prostephanus truncatus (Horn) en semilla de maíz almacenada.

The objective considers to evaluate the biological effectiveness of 9 single insecticide products and in mixture, employees for the control of plagues of the maize (grain stored and of the culture) and to dose recommended for this culture. They were applied by immersion of the grain on a variety of maize tuxpeño to observe the biological effect in mortality terms on large grain borer Prostephanus truncatus, during a period of storage of 6 months, under a design completely at random with 38 treatments, 3 repetitions and one comparison of averages (Tukey 0,05); with the intention of analyzing the insecticide that presents the best option for the treatment to the maize seed stored for investigation. The variance analysis indicated significant differences in percentage of mortality of the insects for each one of the treatments. The effect insecticides was of 100% to 5.53% of mortality. The insecticides deltametrina, permetrina and carbaryl expressed greater percentage of mortality on the others, including the witness (0% mortality). The mixtures in which good result was had are: deltametrina + pirimifos metil, deltametrina + carbaryl, permetrina + carbaryl, carbaryl + pirimifos metil, carbaryl + clorpirifos etil. The test of germination of seeds at the end of the evaluation showed, that the viability of the same one was not affected by the treatments.

Effect of wood ash and conidia of Beauveria bassiana (Balsamo) Vuillemin on mortality of Prostephanus truncatus (Horn)

A series of experiments was carried out to investigate the effect of treating maize with wood ash and entomopathogenic fungus on the mortality of the larger grain borer Prostephanus truncatus. Jars of maize were treated with ash and/or conidia of Beauveria bassiana at doses of 0.0005, 0.005, 0.05 and 0.2 g conidia/g ash/100 g maize. Adult P. truncatus were placed on the maize and numbers of live and dead insects were assessed weekly. Ninety-five per cent mortality of P. truncatus was observed after 1 week and 100% mortality after 2 weeks in maize treated with the highest dose of conidia with ash (0.2 g/g). Mortality of P. truncatus in all ash with conidia treatments was significantly higher than untreated controls over a 4-week period, except the lowest dose of conidia at week 4. The three highest concentrations of conidia per gram of ash resulted in significantly (1% level) higher mortality of P. truncatus than ash alone. In an experiment to investigate the possible synergy of ash and conidia, there were no significant differences in mortality of P. truncatus between treatments with the same concentration of conidia regardless of whether the conidia were mixed with ash or applied alone. Larval populations of P. truncatus were observed in all treatments without ash, but only one larva was observed in one replicate of a treatment containing ash suggesting that ash has an important effect in preventing the establishment of a second generation of insects.