Species diversity and distribution of lepidopteran stem borers in South Africa and Mozambique

Country‐wide surveys of lepidopteran stem borers in wild host plants were undertaken between 2006 and 2009 in South Africa and 2005 and 2010 in Mozambique. A total of 4438 larvae were collected from 65 wild host plants in South Africa and 1920 larvae from 30 wild host plants in Mozambique. In South Africa and Mozambique, 50 and 39 stem borer species were recovered, respectively, with four new species and two new genera among noctuids. Less than 5% of the total number of species collected are considered to be economically important in Africa. These species were Busseola fusca (Fuller) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae) and Sesamia calamistis Hampson (Noctuidae). Data from this study and others in East Africa on the very low abundance of stem borers in wild host plants question the putative role of wild host plants as reservoir for stem borer pests. One new host plant family (Prioniaceae), as well as 24 and 13 wild hosts from South Africa and Mozambique respectively, was added to the list of known hosts in Africa.     

Distribution,relative importance,and agro-climatic preferences of cereal stem borers in Eastern Ethiopia

Abstract

The distribution and relative importance of lepidopteran stem borers attacking maize and sorghum were investigated in farmers’ fields during the main cropping seasons of 2015 and 2016 across three main agro-climatic zones (ACZs) of eastern Ethiopia. Three stem borer species, namely Busseola fusca Fuller, Chilo partellus Swinhoe and Sesamia calamistis Hampson were found attacking these crops with different levels of distribution and abundance among ACZs. Busseola fusca was the only borer species in the highlands and dominant (67%) in the midhighland zones, while C. partellus was predominant (75%) in the lowlands. The abundance of S. calamistis was low across its distribution range. Across both years, mean plant infestation by B. fusca ranged from 20.38 in lowlands to 42.97% in highlands. Chilo partellus resulted in a mean infestation of 27.38% in the midaltitude to 68.24% in lowlands. Mean density of larvae per plant was higher for C. partellus (2.85), followed by B. fusca (1.41) and S. calamistis (0.46). Moreover, within each ACZs, variation in plant damage variables was observed between the study periods. These spatio-temporal differences in community structures of stem borers are discussed particularly in relation to agro-climatic requirements.     

Host preference of Xanthopimpla stemmator (Hymenoptera: Ichneumonidae) and its reproductive performance on selected African lepidopteran stem borers

The Asian pupal parasitoid, Xanthopimpla stemmator Thunberg, was imported into East Africa as a classical biological agent of lepidopteran cereal stem borers. Preference of X. stemmator females for four common borers of maize and sorghum; the crambid Chilo partellus (Swinhoe), the pyralid, Eldana saccharina Walker, and the noctuids, Busseola fusca Fuller and Sesamia calamistis Hampson, was investigated. Pre-adult experience of X. stemmator females did not influence choice of host. In dual choice tests, more B. fusca were attacked than E. saccharina, while E. saccharina were attacked more than Ch. partellus. Life table studies on three of the hosts revealed that the intrinsic rate of increase was highest when X. stemmator was reared on S. calamistis. Net reproductive rates, mean generation times and doubling times were not different between hosts. Results suggest that X. stemmator can be successfully reared on the three stem borer species and released in areas where any combination of the three hosts occurs.     

Host Suitability of Four Cereal Stem Borers (Lepidoptera: Crambidae, Noctuidae) for Different Geographic Populations of Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) in Kenya

This study focused on the suitability of four species of cereal stem borers for the development of five geographic populations of Cotesia sesamiae (Cameron). C. sesamiae, an indigenous larval parasitoid of gramineous stem borers, is widespread in Africa. Four stem borers, Chilo partellus (Swinhoe), Chilo orichalcociliellus Strand (Lepidoptera: Crambidae), Busseola fusca Fuller, and Sesamia calamistis Hampson (Lepidoptera: Noctuidae), were offered to C. sesamiae for oviposition. Parasitoid individuals originated from five locations in Kenya. Biological parameters such as developmental time, percentage parasitism, progeny production, mortality of immature parasitoids, and proportion of female progeny were compared across host species. The two populations from western Kenya developed well on B. fusca. However, populations from the coast and the Eastern Province could not successfully parasitize B. fusca. With the exception of B. fusca, the percentage of hosts successfully parasitized by the different C. sesamiae populations was not different. The size of the host appeared to be an important factor influencing the development and reproductive potential of the parasitoid. We conclude that the different parasitoid populations were adapted to location-specific characteristics. Parasitoid–host compatibility must be evaluated before release for better establishment and colonization.     

Distribution and relative importance of cereal stem borers and their natural enemies in the semi-arid and cool-wet ecozones of the Amhara State of Ethiopia

The distribution and relative importance of lepidopteran and coleopteran stem borers and their natural enemies on maize and sorghum were studied in cereal growing zones of the Amhara State of Ethiopia from 2003 to 2004. Sorghum is the major crop in semi-arid eastern and maize in the cool-wet western zones of the Amhara state. Four administrative zones, 10 districts and 88 localities in the semi-arid ecozone (SAE) and four zones, 19 districts and 71 localities in the cool-wet ecozone (CWE) were chosen for the study. In SAE, the species composition was 91% Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), 8% Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and 1% Sesamia calamistis Hampson (Lepidoptera: Noctuidae). In the CWE, maize and sorghum are grown in different ecozones and thus B. fusca was the dominant species on sorghum, whereas 61% B. fusca and 39% S. calamistis were recorded on maize. Borer density generally increased with crop growth stage. C. partellus parasitism by C. flavipes Cameron (Hymenoptera: Braconidae), which occurred only in SAE, varied among districts ranging from 5% to 39%. In the CWE, unidentified nematodes parasitized medium-sized B. fusca larvae during the wet months. Population of native parasitoids was very low. The coleopteran borer, Rhynchaenus niger (Horn) (Coleoptera: Rhynchophoridae), attacked sorghum plants in both regions. Sorghum yields were negatively related to plant damage variables and positively to larval parasitism and plant growth variables. On maize, plant damage was too low to affect yields. Taylor’s power law indicated aggregated distribution for C. partellus and B. fusca larvae and pupae combined.     

Vetiver grass (Vetiveria zizanioides (L.) Nash) as trap plant for Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) and Busseola fusca (Fuller) (Lepidoptera: Noctuidae)

The preference of lepidopterous stem borer moths to oviposit on certain wild host plants can be exploited in habitat management systems by using those hosts as trap crops. Vetiver grass (Vetiveria zizanioides (L.) Nash) was evaluated for its attractiveness and suitability to the pyralid Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) and the noctuid Busseola fusca (Fuller) (Lepidoptera: Noctuidae). Two choice tests were conducted in the laboratory and in the greenhouse to determine oviposition choice of C. partellus for maize, Vetiver and rice (Oryza sativa L.), and of B. fusca for Vetiver and maize. C. partellus larval survival was evaluated in green house studies. Results indicated that C. partellus chose Vetiver grass over maize though larval survival on Vetiver was extremely low. B. fusca did not show any host preference.     

Distribution,pest status and agro-climatic preferences of lepidopteran stem borers of maize in Kenya

Lepidopterous stem borers are the main field insect pests that attack maize, Zea mays L. in tropical Africa. A survey was carried during the long and short rain cropping seasons of 2002 / 2003 across six main agro-climatic zones (ACZs) to determine the spatial distribution of important stem borer species in Kenya. A total of 474 visits were made in the seventy-eight localities conveniently chosen to represent each of the six ACZs. 189,600 stems were checked for infestation, of which 27,799 infested stems were destructively cut and dissected for stem borer larvae identification. An average of 1.4 stem borer larvae were recovered per infested plant. 54.5% of the recovered larvae were identified as Chilo partellus (Swinhoe) (Crambidae), 39.7% as Busseola fusca (Fuller) (Noctuidae), 4.5% as Sesamia calamistis Hampson (Noctuidae) and 0.8% as Chilo orichalcociliellus (Strand) (Crambidae). Minor species present included Eldana saccharina Walker (Pyralidae), Sesamia nonagrioides (Lefebvre) (Noctuidae), Sesamia cretica Lederer (Noctuidae), Sesamia sp. (Noctuidae), Sciomesa piscator Fletcher (Noctuidae), Busseola sp near phaia (Noctuidae), Chilo sp, Ematheudes sp 1 (Pyralidae) and Ematheudes sp 2 (Pyralidae). Farms were grouped into respective ACZs for statistical analysis and subsequent comparison of dominant species. Results indicated that B. fusca was the dominant stem borer species in high potential zones (highland tropics, moist transitional zone and moist midaltitude) while the exotic C. partellus dominated smallholder farms in low potential zones (dry midaltitude, dry transional and lowland tropical zone). Within each ACZs, there was evidence of variation in species proportions between seasons. These spatio-temporal differences in community structure are discussed in terms of agro-climatic biological adaptations.     

The effect of Bt maize on Sesamia calamistis in South Africa

Bt maize, Zea mays L. (Poaceae) expressing Cry 1Ab insecticidal proteins was introduced for control of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) in South Africa after its development for control of crambid borers in North America. In the light of the reportedly lower toxicity of Bt maize to certain Noctuidae borers, the effect of Bt maize was evaluated on Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae). The characteristic larval behaviour of S. calamistis may result in reduced exposure to Bt toxin and subsequent high levels of survival. Larvae do not feed on plant whorls like other borer species but penetrate stems directly from behind leaf sheaths where eggs are laid. Greenhouse and laboratory bioassays were done with three Bt maize hybrids and their iso‐hybrids. ‘Whole plant methods’ were used and potted plants artificially infested with eggs or larvae and survival recorded over time. Larval survival was also determined on different plant parts (whorls, stems, tillers, and ears) over time. Bt maize was shown to be highly toxic to S. calamistis. No larvae survived longer than 12–18 days on Bt maize plants in any of the experiments. Adults did not differentiate between Bt and non‐Bt plants in oviposition choice experiments. Sesamia calamistis is polyphagous and occurs in mixed populations with other borer species with which it shares many parasitoid species in Africa. The ecological impact of local extinction of S. calamistis caused by this highly effective transgenic event is therefore not expected to be great.     

Increase in cereal stem borer populations through partial elimination of natural enemies

An insecticide exclusion method was used to evaluate the effect of parasitoids on level of infestation by the stem borers, Busseola fusca (Fuller) and Chilo partellus (Swinhoe), in grain sorghum. In field trials conducted at Brits and at Delmas, South Africa, a selective organophosphate insecticide, dimethoate, was applied twice weekly at each site to three subplots whereas three other identical subplots served as controls. Twelve plants were randomly selected from each subplot at weekly intervals and removed from the field. In the laboratory all plants were dissected to record borer infestation. In order to determine parasitism levels egg batches were kept in Petri dishes and all borer larvae and pupae were kept individually in vials until either parasitoids or moths emerged. At Brits ca. 97% of borers were C. partellus and 3% B. fusca, whereas at Delmas 37.5% were C. partellus and 62.5% B. fusca. The most abundant parasitoids of B. fusca were Cotesia sesamiae (Cameron) and Bracon sesamiae Cameron. The dominant parasitoids of C. partellus at both sites were C. sesamiae, Stenobracon spec., Dentichasmias busseolae Henrich and Pediobius furvus (Gahan). No egg parasitoids were found. At both sites, infestation levels in the sprayed plots were significantly higher than in the untreated plots. On the other hand, parasitism levels of borers in the unsprayed plots were significantly higher than in the treated plots. It was concluded that the higher infestation level of sorghum by stem borers in the sprayed plots was because of partial elimination of parasitoids and possibly other natural enemies by the pesticide.     

Factors affecting the bionomics of the eastern African egg parasitoid Trichogramma bournieri Pintureau & Babault (Hymenoptera: Trichogrammatidae)

The trichogrammatid Trichogramma bournieri Pintureau & Babault is a polyphagous parasitoid of eggs of several cereal stemborer species in eastern Africa. The effects of host species, host age and duration of host deprivation on the performance of the parasitoid were studied in the laboratory. Host acceptance and suitability were tested using five stemborer species. The noctuids Sesamia calamistis Hampson, Sesamia nonagrioides (Lefebvre), Busseola fusca (Fuller) the crambid Chilo partellus (Swinhoe) and the pyralid Eldana saccharina Walker were successfully parasitized by T. bournieri. Parasitism, number of progeny and developmental time varied significantly with host species. The eggs of S. calamistis and B. fusca were the most suitable, whereas those of E. saccharina were the least suitable. While parasitism and number of progeny tended to decrease with age of hosts, there were no significant differences in sex ratio. Longevity of the parasitoid increased with increase in deprivation of hosts from 0 to 12 days. Average lifetime fecundity per female decreased, indicating resorption of eggs.     

Composition of stem borer communities in selected vegetation mosaics in Kenya

Busseola fusca (Fuller), Sesamia calamistis Hampson, Chilo partellus (Swinhoe) and Chilo orichalcociliellus (Strand) are important stem borer pests of maize and sorghum in East Africa. Persistence of these pests in crop fields is blamed on the influx of diaspore populations from the neighbouring natural habitats. In addition to pest species, natural habitats support numerous non-economic stem borer species, some not known to science. However, due to growing human populations and accompanying global change, some of the natural habitats are undergoing rapid changes, a process that may result in the evolution of “new” pest species. In this study, we investigated stem borer species diversity in four different vegetation mosaics in Kenya, with an aim of establishing the differences in species composition and distributions in both wild and cultivated habitats. We identified 33 stem borer species belonging to 14 different genera in the four families; Noctuidae, Crambidae, Pyralidae and Tortricidae from 37 plant species. In addition to the above stem borer pest species, we found three more species, Busseola segeta Bowden, Pirateolea piscator Fletcher and Eldana saccharina Walker, in the cultivated fields. Together, stem borer pests varied in distribution among vegetation mosaics, suggesting differences in ecological requirement. Despite the variations in distribution patterns, stem borer pests co-existed with non-economic species in the natural habitats, communities that are facing threats due to ongoing habitat changes. This paper discusses the likely impacts of habitat changes on both pest and non-economic species.     

Superior basal and plastic thermal responses to environmental heterogeneity in invasive exotic stemborer Chilo partellus Swinhoe over indigenous Busseola fusca (Fuller) and Sesamia calamistis Hampson

Lepidopteran stemborers are the most destructive insect pests of cereal crops in sub‐Saharan Africa. In nature, these insects are often exposed to multiple environmental stressors, resulting in potent impact on their thermal tolerance. Such environmental stressors may influence their activity, survival, abundance and biogeography. In the present study, we investigate the effects of acclimation to temperature, starvation and desiccation on thermal tolerance, measured as critical thermal limits [critical thermal minima (CT_min) and maxima (CT_max)] on laboratory‐reared economic pest species Chilo partellus Swinhoe (Lepidoptera: Crambidae), Busseola fusca (Fuller) and Sesamia calamistis Hampson (Lepidoptera: Noctuidae) using established protocols. Low temperature acclimation results in improved CT_min for B. fusca and C. partellus, whereas high temperature acclimation enhances the same trait for B. fusca and S. calamistis. Similarly, high temperature and starvation pretreatment improve CT_max for C. partellus relative to S. calamistis and B. fusca. In addition, starvation and desiccation pretreatments improve CT_min for all stemborer species. Furthermore, rapid cold‐hardening (RCH) enhancs CT_min for B. fusca and C. partellus, whereas rapid heat‐hardening (RHH) improves the same trait for C. partellus. However, RCH and RHH impair CT_max for all stemborer species. These findings show differential thermal tolerances after exposure to heterogeneous environmental stress habitats. Chilo partellus, of exotic origin, shows a higher magnitude of basal thermal tolerance plasticity relative to the indigenous African species S. calamistis and B. fusca. This indicates that C. partellus may have a fitness and survival advantage under climate‐induced heterogeneous environments, and also have a greater chance for geographical range expansion and invasion success compared with the indigenous B. fusca and S. calamistis.     

Performance of Trichogrammatoidea sp. nr lutea Girault (Hymenoptera: Trichogrammatidae) collected from Mussidia spp. in Kenya on eggs of six lepidopteran hosts

Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae), an important pest of maize ears in West Africa, has never been reported to attack crops in East and southern Africa (ESA), though it was found on various wild host plants in these regions. It was suggested that in ESA M. nigrivenella might be under natural control. In Kenya, exploration for natural enemies associated with Mussidia spp. yielded several parasitoids including a trichogrammatid egg parasitoid, Trichogrammatoidea sp. nr lutea Girault. The ability of T. sp. nr lutea to attack the eggs of several lepidopteran species found in Kenya was studied. The lepidopterans included the noctuids Busseola fusca (Fuller) and Sesamia calamistis (Hampson), the pyralids Eldana saccharina Walker, Mussidia fiorii Cecconi and de Joannis and Mussidia‘madagascariensis’, and the crambid Chilo partellus (Swinhoe). The former three species also infest cereals in West Africa. Trichogrammatoidea sp. nr lutea successfully attacked and developed in eggs of all six species indicating its potential to exploit other lepidopteran pests of maize in West Africa. Busseola fusca and S. calamistis were the most suitable hosts and had the largest number of eggs parasitized and progeny per female wasp where E. saccharina and C. partellus were the poorest hosts. The host species used to rear the parasitoid and the age of egg also significantly affected the total number of host eggs parasitized by the parasitoid. It was concluded that the ability of T. sp. nr lutea to exploit lepidopterans that are also pests of maize in West Africa may enhance biological control of M. nigrivenella and it should be considered for translocation to that area from Kenya.     

Dominance of spotted stemborer Chilo partellus Swinhoe (Lepidoptera: Crambidae) over indigenous stemborer species in Africa's changing climates: ecological and thermal biology perspectives

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Duration of diapause in the stem borers, Busseola fusca and Chilo partellus

The duration of diapause in the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) was studied in South Africa by collecting diapausing larvae from the field throughout winter (April–August). B. fusca larvae emerged as moth around the middle of October regardless of the date of collection and the length of time they were kept in the laboratory under constant 21 °C. C. partellus larvae collected in April–June emerged in November, those collected in July emerged in October, and those collected in August emerged in September. Regardless of the collection date C. partellus started to emerge from diapause earlier and moth emergence lasted up to twice as long as in B. fusca. Under laboratory conditions at 60% RH both borer larvae lost about 50% of their body mass during diapause. When provided with water B. fusca larvae lost about 30% of their body mass and adults emerged 20 days earlier than when kept dry. C. partellus, on the other hand, lost only 13% of their body weight and emerged 34 days earlier. The differences between the two species are discussed in light of different types of diapause; i.e., obligatory diapause in B. fusca and facultative diapause in C. partellus.     

Diversity and abundance of lepidopteran stem borers and their host plants in Ethiopia

Lepidopteran stem borers are among the most important insect pests of maize, sorghum and sugarcane in sub‐Saharan Africa. Except for Chilo partellus, the other stem borer pests in Ethiopia are indigenous to Africa and are assumed to have coevolved with some native grasses and sedges in the natural habitat. In addition to pest species, natural habitats harbour diverse non‐economic stem borer species, some of which are new to science. However, with the growing threats to natural habitats, some non‐economic stem borer species may switch or expand their host ranges to include cultivated crops and evolve as “new” pests. Besides host switch, some of the unknown species currently limited to natural habitats may disappear. We examined the diversity, abundance and interactions of lepidopteran stem borers and their wild host plants in five different vegetation mosaics in Ethiopia. The stem borer species diversity varied among vegetation mosaics and host plants. Forty‐four stem borer species belonging to 14 different genera in the families of Noctuidae, Crambidae, Pyralidae and Tortricidae were recorded from 34 wild host plants and through light trap. Among these families, Noctuidae was the highest in species richness in which 31 species were identified, out of which 15 species and two genera were new to science. This paper discusses the ecological interpretation of host plant–stem borer species interactions, particularly in relation to habitat disturbances.     

Stem borer infestation of cereal crops in Jere,the Sudan-Sahelian savanna region of Nigeria

Field data collected during the rainy season of two years, 2010 and 2011, were used to determine the per cent plant infestation and stem borer abundance on cultivated cereal crops grown by farmers' in Jere or the Sudan-Sahelian savanna ecological region of Nigeria. Stem borers were recovered using destructive sampling. Mean total per cent plant infestation and stem borer abundance per farmers' field were significantly higher on millet (40% and 25 individuals, respectively) and sorghum (30% and 21 individuals, respectively) than on maize (19% and 13 individuals, respectively). Of the five stem borer species found in this study, Coniesta ignefusalis (Lepidoptera: Pyralidae) (3.5)/Chilo sp. nr. aleniellus (Lepidoptera: Crambidae) (2), Busseola fusca (Lepidoptera: Noctuidae) (3.1)/Sesamia calamistis (Lepidoptera: Noctuidae) (2.4) and S. calamistis (2.9), with significantly higher number of individuals per plant, tended to be more important pests on millet, sorghum and maize crops, respectively. Although, mean total per cent plant infestation and abundance of stem borers in this study were generally moderate, further studies on the effects of different types of cereals intercropping (locally practiced) on stem borer infestation and abundance should ascertain the true importance of these pest species in the Sudan-Sahelian savanna ecological region of Nigeria.     

Larval dispersal of the invasive fall armyworm,Spodoptera frugiperda,the exotic stemborer Chilo partellus,and indigenous maize stemborers in Africa

Larval dispersal either through ballooning or crawling results in a redistribution of the insect population and infestations within and between plants. In addition, invasive species, such as the fall armyworm (FAW), Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae), and the exotic stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), may displace indigenous stemborers on maize in Africa. To test whether larval dispersal activity may play a role in the displacement of indigenous stemborers, larval dispersal was compared between FAW, C. partellus, and the indigenous species Busseola fusca (Fuller) and Sesamia calamistis (Hampson) (both Lepidoptera: Noctuidae). Twenty potted maize plants were infested with one batch of eggs either from stemborers (B. fusca, S. calamistis, or C. partellus) or from FAW and monitored in the greenhouse for ballooning activities. After egg hatching, both ballooning and non-ballooning larvae were identified according to species and counted. FAW neonate larvae had greater potential for ballooning off than stemborers, irrespective of species. For each species, more females dispersed than males, and their survival rate was higher than that of non-ballooning larvae. In addition, plant-to-plant larval movements were studied using 6.25-m² plots of caged maize in a completely randomized design with five replicates. FAW was found to have wider dispersal and plant damage potential than any of the stemborer species. In conclusion, in contrast to C. partellus, the invasive characteristic of FAW can be explained, in part, by its higher larval dispersal activity compared to stemborers. This difference in larval dispersal might also be considered in sampling plans for monitoring pest density in the field.     

Stem borer's species composition,abundance and infestation on maize and millet in Maiduguri,Nigeria

The species composition, abundance and plant infestation of stem borers attacking maize and millet were investigated in farmers' fields during the cropping season of 2010 and 2011 in Maiduguri, Nigeria. Stem borers were collected via destructive sampling. In total, three stem borer species (Busseola fusca, Sesamia calamistis and Coniesta ignefusalis) were found, of which S. calamistis (64%) and C. ignefusalis (72%), respectively, were predominant on maize and millet. Across both years, whereas mean plant infestation ranged from 4.8% on millet to 20.8% on maize, mean stem borer abundance ranged from 1.6 individuals on millet to 13.8 individuals on maize. Mean total plant infestation and stem borer abundance varied with different years and both were significantly higher during the 2010 than 2011 cropping season. In spite of the generally low stem borer abundance per farmers' field, plant infestation particularly on maize plants seems to be moderate during different years.     

Acceptance and suitability of four lepidopteran stemborers for the development of the pupal parasitoid Xanthopimpla stemmator (Hymenoptera: Ichneumonidae)

Xanthopimpla stemmator (Thunberg), a solitary endoparasitoid of lepidopteran stemborer pupae, was recently imported into East Africa as a candidate biological control agent of gramineous stemborers. Suitability of Busseola fusca Fuller, Chilo partellus (Swinhoe), Eldana saccharina (Walker) and Sesamia calamistis Hampson, for the development of X. stemmator was studied in the laboratory. One- to 6-day-old laboratory reared pupae of the four stemborer species were exposed to naïve X. stemmator females. All host pupae and ages were acceptable for oviposition. The parasitoids inflicted multiple probe wounds on 67.8% of pupae exposed. B. fusca, C. partellus and S. calamistis were equally suitable with 56.4, 59.4 and 52.3%, respectively, of probed pupae leading to emergence of adult parasitoids. E. saccharina was less suitable with only 22.6% of probed pupae producing parasitoids. Emergence of parasitoids did not differ significantly across the six pupal ages for B. fusca and S. calamistis, but varied for C. partellus and E. saccharina. No parasitoids emerged from 6-day-old E. saccharina pupae. Realized fecundity of females reared on the four stemborer pupae showed that fewer progeny were produced by females emerging from E. saccharina than females reared on the other three stemborer species. Eldana saccharina may be a poor host for X. stemmator in Kenya, but this parasitoid is a potential candidate for biological control of B. fusca, C. partellus and S. calamistis.