Maize Stem Borer Research Articles

Ecological Genetics and Host Range Expansion by Busseola fusca (Lepidoptera: Noctuidae).

The host plant range of pests can have important consequences for its evolution, and plays a critical role in the emergence and spread of a new pest outbreak. This study addresses the ecological genetics of the indigenous African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae), in an attempt to investigate the evolutionary forces that may be involved in the recent host range expansion and establishment of this species in Ethiopian and southern African sugarcane. We used populations from Ethiopia, Zimbabwe, and South Africa to examine whether the host range expansion patterns shared by the Ethiopian and the southern African populations of B. fusca have evolved independently. Base-pair differences in the cytochrome oxidase I (COI) gene were used to characterize haplotype diversity and phylogenetic relationships. There were seven haplotypes among the 30 sequenced individuals collected on four host plant species from 17 localities in the four countries. Of the seven COI haplotypes identified, the two major ones occurred in both sugarcane and maize. Genetic analyses revealed no detectable genetic differentiation between southern African B. fusca populations from maize and sugarcane (FST = 0.019; P = 0.24). However, there was strong evidence of variation in genetic composition between populations of the pest from different geographic regions (FST = 0.948; P < 0.001). The main implication of these findings is that the B. fusca populations in maize in southern Africa are more likely to shift to sugarcane, suggesting that ecological opportunity is an important factor in host plant range expansion by a pest.

Chemical cues modulating electrophysiological and behavioural responses in the parasitic waspCotesia sesamiae

A better understanding of the chemical cues employed by parasitoids to locate their herbivore hosts will contribute towards effective exploitation of parasitoids as biological control agents against damaging crop pests. The current study was conducted to establish key bioactive compounds mediating behavioural response in the parasitic wasp Cotesia sesamiae (Cameron, 1906) (Hymenoptera: Braconidae) by employing electrophysiological techniques and behavioural studies. Electroantennogram (EAG) recording with synthetic equivalents of herbivore-induced plant volatiles (HIPVs) using C. sesamiae confirmed that 13 compounds elicited electrophysiological activity. In an olfactometer bioassay, only (E)-4,8-dimethyl-1,3,7-nonatriene, (E)-β-farnesene, and (E,E)-4,8,-trimethyl-1,3,7-tridecatetraene elicited behavioural responses from the parasitoid when tested individually at a natural dose, while (R)-linalool and (E)-caryophyllene were attractive at the highest test dose. Other EAG-active HIPVs were not attractive either at lower or higher concentrations, suggesting their role as blend components rather than functioning as attractants by themselves. In contrast, nine-component synthetic HIPV blends formulated in the same ratio and concentration as in a natural sample was as attractive as the original headspace sample. By providing further insights into maize–stemborer–parasitoid tritrophic interactions, results from this study will help in selecting crop cultivars emitting appropriate HIPVs to attract natural enemies and perhaps repel damaging crop pests.

Trap cropping with Napier grass, Pennisetum purpureum (Schumach), decreases damage by maize stem borers

Napier grass, Pennisetum purpureum (Schumach), in combination with intercrops has been used successfully in habitat management for maize stem borers in Africa. The use of Napier grass only as a trap or barrier plant for Chilo partellus (Lepidoptera: Crambidae) and Busseola fusca (Fuller) (Lepidoptera: Noctuidae) was evaluated in this study. Napier grass borders were planted only on two sides of small-scale farmers’ maize fields, since planting of perennial trap crops on all sides of fields hampered mechanical cultivation. C. partellus was the dominant borer species, followed by B. fusca and Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae). Reductions between 0% and 27.4% in the incidence of borer-infested plants were observed on the 16 farms evaluated in this study. The results show that Napier grass as trap/barrier crop suppresses stem borer numbers in maize fields.

Homecoming of Brachiaria: Improved Hybrids Prove Useful for African Animal Agriculture

Species of the genus Brachiaria originate primarily from Africa, where they are constituents of natural grasslands. Due to their adaptation to acidic, low-fertility soils, millions of hectares of Brachiaria species have been sown as improved pastures in South and Central America, especially B. brizantha cv. Marandu and B. decumbens cv. Basilisk. Due to B. decumbens’ susceptibility to spittlebug insect pests in the Americas, CIAT in Colombia and EMBRAPA in Brazil initiated breeding programmes in the 1980s. First cultivars released from CIAT's breeding programme – cvs. Mulato and Mulato-II – have also been investigated in African countries. They have been examined for integration in conservation agriculture systems (Madagascar), for drought and acidic soil tolerance (Rwanda) and for intercropping forages in dairy systems (Uganda, Madagascar), among others. Seed sales to African countries suggest that an area of at least 1,000 ha has been sown so far. The largest adoption of cv. Mulato-II is currently happening in eastern Africa, where it is used by over 20,000 farmers as a trap plant in the push-pull system for control of maize stem borers and parasitic Striga weed. Cv. Mulato-II's particular advantage is its relatively high crude protein content due to greater leafiness and thinner stems than those of traditional Napier grass, resulting in higher nutritive quality. Yet new pest challenges have emerged, requiring further research attention. Diverse hybrids are in the pipeline for release, among them those that are suitable for cut-and-carry systems which are prevalent in eastern Africa. This paper reviews research, development and incipient adoption of new Brachiaria hybrids in African countries.

In vitro Evaluation of Aqua Extracts of Some Botanicals against Maize Stem Borer, Busseola fusca F. (Lepidoptera: Noctuidae)

The present study was conducted to determine the comparative efficacy and bioactivity of aqueous extracts of four botanicals (leaf, root bark, flower) under in vitro condition. Cypermethrin 1% G was used as standard check and untreated control against maize stem borer in maize (Zea mays L.), during 2012 at Ambo Plant Protection Research Center, Ethiopia. The treatments were aqueous leaf extract of Nicotiana spp. L. and Cymbopogon citratus, root bark aqueous extract of Securidaca longepedunculata F., and flower extract of Chrysanthemum cinerariaefolium at 5% concentration. The cumulative data revealed that the standard check-Cypermethrin 1% G at rate of 0.3 kg/ hectare recorded significantly higher mean percent mortality of maize stem borer, Busseola fusca, over all the other treatments. Among the botanical extracts, C. cinerariaefolium and C. citrates 5% concentration was recorded higher efficacy mean mortality (75 and 58.33), respectively, against B. fusca within three days, and found to be at par with some of the other botanical extracts. The Nicotiana spp. leaf extracts and S. longepedunculata root bark extract showed significantly lower efficacy mean mortality.

Genetic diversity analysis in tropical maize germplasm for stem borer and storage pest resistance using molecular markers and phenotypic traits

One hundred maize inbred lines and eighty four hybrids were characterized for resistance to maize stem borer and post-harvest insect pests. This was achieved using genetic distance and population structure based on simple sequence repeat (SSR) markers and biophysical traits. The test materials were evaluated for stem borer, maize weevil and larger grain borer (LGB) resistance. Leaf samples were harvested from 10 healthy plants per genotype and bulked. Genomic DNA was extracted using a modified version of mini-prep Cetyl Trimethyl Ammonium Bromide (CTAB) method. The samples were genotyped with 55 SSRs makers. Univariate analysis of variance was done using the general linear model procedure of SAS statistical package. Rodgers genetic distance was calculated for all data sets as a measure of genetic distance using NTSYS-pc for Windows. The distance matrices were used to generate phenograms using the unweighted pair group method based on arithmetic average (UPGMA) method in MEGA5. The genotypes were assigned into different populations using population structure software. The data was further subjected to discriminant and principal component analysis to group the gnotyoes. Analysis of molecular variance within and among the different populations was done using arlequin. There were significant differences (P ≤ 0.001) for all the biophysical traits evaluated. The SSR marker data estimated successfully the close relationship among different hybrids and inbred lines within clusters. Comparisons of the different multivariate analyses revealed high concordance among the different approaches of analyses. The results of this study can be directly used by breeding programs to develop resistant genotypes.

Variations in Stem Borer Infestation and Damage in Three Maize (&amp;lt;i&amp;gt;Zea mays&amp;lt;/i&amp;gt; L.) Types in Southern Guinea Savanna and Rainforest Zones of Nigeria

The effects of location, maize types and borer control with carbofuran (Furadan 3G®) on the severity of maize stem borer infestation and damage was investigated in the late maize planting season of 2011. Treatments were laid out in randomized complete block design using a split-slip-plot factorial arrangement. Whole plot factor consisted of two locations (Southern Guinea Savanna and Rainforest agro-ecological zones of Nigeria), subplot factor consisted of 1.5 kg a.i.ha-1 and 0.0 kg a.i.ha-1 of carbofuran, while the sub-sub-plot factor comprised of three endosperm types of maize (flint, pop and sweet corn). Stem borer infestation (quantified by dead heart count and larval population per plant) and damage (quantified by %lodged stem, %bored internodes, %bored ears, number of exit holes, number of stem borer cavities and number of damaged seeds per plant) as well as yield were compared. Results revealed that borer infestation and damage were significantly higher (P 0.05) location × carbofuran × maize type and location × maize type effect was detected. However, significant (P < 0.05) location × carbofuran and carbofuran × maize type interaction effects were observed. We conclude that in both agro ecologies, flint corn was more tolerant of borer attack while sweet corn was more susceptible compared to either flint or popcorn. In addition, carbofuran at 1.5 kg a.i.ha-1 can significantly reduce stem borer population in the three maize types.

Biology and Development ofSturmiopsis parasitica(Diptera: Tachinidae) on Different Species and Populations of Maize Stemborers in Zimbabwe and an Assessment of Its Suitability for Redistribution in Africa

The tachinid larval parasitoid Sturmiopsis parasitica (Curran) has a wide distribution in eastern, southern and West Africa where it attacks several species of cereal stemborers. Its development on Busseola fusca Fuller (four populations), Chilo partellus (Swinhoe) and Sesamia calamistis Hampson was evaluated in Zimbabwe in the laboratory. The parasitoid's larviposition patterns and ways to induce its early emergence from diapausing host larvae inside which it overwinters were also studied. Irrespective of the inoculation method used, the four B. fusca populations were equally suitable for parasitoid development. Chilo partellus was a partially suitable host while S. calamistis was completely unsuitable. Mated female parasitoids commenced larviposition at eight days after mating, with a peak being attained on day 15. Placing field-collected diapausing B. fusca larvae in fresh maize stems or in moistened dry stems could bring forward the emergence of S. parasitica from diapausing hosts. The implications of the current findings on the suitability of S. parasitica as a redistribution candidate in Africa are discussed.

The effect of indirect exposure to Cry 1Ab proteins on the biology of the green Lacewing (&lt;i&gt;Chrysoperla Pudica&lt;/i&gt;)

The effect of indirect exposure to Cry 1Ab proteins on the biology of the green Lacewing (Chrysoperla Pudica) Genetically modified (GM) maize that expresses Cry1Ab protein was developed for control of the maize stem borer (Busseola fusca). In this study we evaluated the possible effect of this protein on the non-target organism Chrysoperla pudica, by feeding it with resistant larvae of the target pest. Only a small number of adverse effects were observed on the biology of C. pudica.

3-β-d-Glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc) is an insect detoxification product of maize 1,4-benzoxazin-3-ones

In order to defend themselves against arthropod herbivores, maize plants produce 1,4-benzoxazin-3-ones (BXs), which are stored as weakly active glucosides in the vacuole. Upon tissue disruption, BXs come into contact with β-glucosidases, resulting in the release of active aglycones and their breakdown products. While some aglycones can be reglucosylated by specialist herbivores, little is known about how they detoxify BX breakdown products. Here we report on the structure of an N-glucoside, 3-β-d-glucopyranosyl-6-methoxy-2-benzoxazolinone (MBOA-N-Glc), purified from Spodoptera frugiperda faeces. In vitro assays showed that MBOA-N-Glc is formed enzymatically in the insect gut using the BX breakdown product 6-methoxy-2-benzoxazolinone (MBOA) as precursor. While Spodoptera littoralis and S. frugiperda caterpillars readily glucosylated MBOA, larvae of the European corn borer Ostrinia nubilalis were hardly able to process the molecule. Accordingly, Spodoptera caterpillar growth was unaffected by the presence of MBOA, while O. nubilalis growth was reduced. We conclude that glucosylation of MBOA is an important detoxification mechanism that helps insects tolerate maize BXs.

Effect of Bt-Maize Expressing Cry1Ab Toxin on Non-Target Coleoptera and Lepidoptera Pests of maize in South Africa

While many studies have been conducted on possible effects of Bt-maize on beneficial arthropods, information on its effects on non-target pests of maize is scarce. Bt-maize has been planted in South Africa since 1998 for control of the maize stem borers, Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Pyralidae). No information is available on the possible effects that feeding on Bt-maize may have on other pests exposed to Cry1Ab protein when they attack seedlings or ears of Bt-maize. Important pests attacking maize seedlings are Heteronychus arator (Coleoptera: Scarabaeidae) and Somaticus angulatus (Coleoptera: Tenebrionidae), while Helicoverpa armigera (Lepidoptera: Noctuidae) is a sporadic pest of maize ears. The objectives of this study were to determine the effects of Bt-maize, expressing Cry1Ab protein, on these non-target pests. Laboratory studies in which larvae or adults of these species were fed with Bt and non-Bt-maize leaves or ears were conducted and mortality, growth, fecundity and fertility determined. Feeding on Bt-maize did not have a significant effect on any of these life-history parameters of H. arator or S. angulatus. In greenhouse and laboratory studies with H. armigera no larvae survived to the pupal stage on Bt-maize. This study showed that Cry1Ab-producing maize may protect the crop against H. armigera feeding damage. However, the likelihood of H. armigera becoming resistant to Cry1Ab protein over time, and it becoming an important secondary pest, is high.

Validation of Biocontrol Technology for Suppression of Chilo Partellus (swinhoe) on Kharif Maize in Punjab

The management of maize stem borer, Chilo partellus (Swinhoe) with Trichogramma chilonis @ 100,000 ha -1 ) at 12 days after germination (DAG) was compared with farmer's practice of two sprays of deltamethrin (Decis 2.8 EC @ 200 ml ha -1 at 15 and 30 DAG during kharif 2011 and 2012 at farmer's fields in Punjab. The mean leaf injury due to C. partellus at 20 DAG was 8.04 and 6.87% in biocontrol treatment and farmers practice, respectively. The dead heart incidence of 3.85 and 2.55% in these treatments was significantly lower than untreated control (12.10%). The biocontrol plots recovered 31.18% parasitism compared to farmers practice and untreated control (2.30 and 7.67%). The coccinellids and spiders counts were also higher in biocontrol plots. The grain yield was at par in biocontrol treatments (46.10 q ha -1 ) and farmers practice (48.67 q ha -1 ) while it was significantly lower in untreated control (37.13 q ha -1 ). Similarly, the net returns to the farmer in biological control treatments (Rs. 10008) was comparable to the farmers practices (Rs. 12424). The release of T. chilonis effectively reduced the damage of C. partellus, increased the natural enemies in maize ecosystem and provided convincing monetary benefits to the farmer.

Parameters, Interrelationships with Yield and use of Carbofuran to Control Stem Borers in Maize (Zea mays l.) at Makurdi in the Nigerian Southern Guinea Savanna

Early and late crops of flint, pop and sweet maize (Zea mays L.) were sown in field plots laid in randomized complete block design at the Teaching and Research Farm in 2004. Stem borer infestation and damage were assessed both in the plots treated with 1.5 kg carbofuran/ha and in those not treated for stem borer control. The maize types, as subplot treatments, and carbofuran application vs no application, as main plot treatments, were replicated four times. Borer damage was quantified as percentage dead-heart, bored stems, lodged stems, bored internodes, and as numbers of borer larvae/stem and borer cavities. The damage parameters were correlated with each other and with yield. Busseola fusca Fuller was the most abundant species; borer infestation was 5 times higher in the late than in the early crop and application of carbofuran resulted in 86.8 and 63.5 % control, respectively. Yield loss due to borer damage to the early crop was 14.0%; that for the late crop was 1.5-fold higher. In both crops, maize type exerted no significant effect (P>0.05) on borer damage. Percentage bored internodes was positively and significantly (P < 0.01) correlated with number of bored stems (r = 0.95, early crop; 0.88, late crop), and lodged stems (r = 0.82, early crop; 0.83, late crop). Similarly, bored and lodged stems were positively correlated (r =0.75 and 0.74, respectively in the early and late crop; P < 0.01). Dead-heart was positively correlated with each stem damage parameter; coefficients of correlation were higher for the early than the late crop. All damage parameters were negatively correlated with yield but a robust yield loss predictive model was not found. As such, use of carbofuran against maize stem borers would continue to be prophylactic at Makurdi.

No fitness costs associated with resistance of Busseola fusca (Lepidoptera: Noctuidae) to genetically modified Bt maize

A concern regarding planting of Bt crops is that their widespread cultivation could lead to evolution of insect resistance to Bt toxins. In South Africa, the noctuid maize stem borer (Busseola fusca [Fuller]), is resistant to Bt maize (Zea mays L.; MON810) which produces Cry1Ab protein. The presence of fitness costs in resistant populations could be a valuable component of resistance management since the non-Bt maize refuge may select against resistance. The aim of the study was to determine if there are fitness costs associated with Bt resistance of B. fusca. Life history parameters were compared between individuals of a Bt maize resistant B. fusca population when feeding on Bt or non-Bt maize. Similar comparisons were done using a control population. Field collected larvae as well as their F1-generation were used in the study. The following parameters were compared: pupal mass, moth longevity, fecundity, fertility, larval mass and survival, and sex ratio. Except for LT50-values, no fitness costs were associated with the resistance trait in the highly resistant B. fusca population. The absence of fitness costs and presence of resistant populations may promote the use of a multi-gene strategy which would be expected to impact negatively on fitness.

Efficacy of the aqueous crude seed extract of Millettia ferruginea (Fabaceae) on the maize stemborer Busseola fusca (Lepidoptera: Noctuidae) in the field

The efficacy of different aqueous dilutions of crude seed extract of Millettia ferruginea (Hochst.) Baker (1, 3, 5 and 10%) was evaluated under field conditions in terms of the level of damage and yield loss of maize caused by the maize stemborer Busseola fusca (Fuller) in Hawassa, southern Ethiopia. The insecticide lambda-cyhalothrin 5EC., applied at a rate of 16g active ingredient/hectare, was used as the reference product. The experiment was carried out in a randomized complete block design with four replications. The maize variety A511 was planted in individual plots of 60 m2. Data on stand count, leaf infestation, bored stem and dead heart were collected weekly. Plots sprayed with the 5% concentration of Millettia showed low levels of damage (9–11% leaf infestation, 0.4% dead heart, 14–17% bored stem and <0.2% bored ear), compared with plots sprayed with lambda-cyhalothrin. The treatments with 1 and 3% concentrations of Millettia were inferior to those with lambda-cyhalothrin and 5 and 10% concentrations of Millettia. In contrast, the treatment with the 10% concentration of Millettia led to the death of plants, thereby lowering the yield. About 80% of the total length of individual maize stalks from the untreated plots was internally tunnelled by the feeding larvae, while the internal stem tunnelling was low (< 7%) in plants treated with Millettia at concentrations of 3,5 and 10%. Among the treatments with Millettia, higher yields (37–48 decitonnes/hectare) were obtained from maize plots treated with 5% concentration. The use of the aqueous crude seed extract of M. ferruginea at a concentration of 5% applied two to three times is recommended for the control of B. fusca in maize.

Evaluation of pesticide tolerant strain of Cotesia flavipes Cameron (Hymenoptera: Braconidae) on maize stem borer, Chilo partellus (Swinhoe)

Field evaluation of pesticide tolerant strain of Cotesia flavipes Cameron, a gregarious larval endoparasitoid of the maize stem borer, Chilo partellus (Swinhoe) was carried out and the economics of such evaluation was worked out. Releases of the pesticide tolerant parasitoid strain, prior to application of pesticide or after application resulted in significantly higher net returns and yield, as compared to the releases of susceptible parasitoid strain and untreated control. Four releases of the tolerant parasitoid at 2000/ha at 500 per release registered maximum number of parasitized cocoons (52.6 per larva), higher yields (4019 kg/ha) and net profits (Rs. 7807 kg/ha), followed by two releases of the tolerant strain with two sprays of insecticide (40.8, 3809 kg/ha and Rs. 6847/ha, respectively). The insecticidal treatment gave higher net profits and yields than all other treatments. However, the additional costs, ecological hazards and pesticide residues (likely to occur) do not outweigh the benefits of biological control. Key words: Cotesia flavipes, Chilo partellus, population, pesticide tolerance.

English

&nbsp; The quality of laboratory reared stem borer species for screening of maize varieties is usually&nbsp; questioned by end user cereal breeders. A quality check study was performed in a screen house at&nbsp; KARI-Katumani to evaluate the quality of eight-year old laboratory reared stem borer, Chilo partellus&nbsp; (Swinhoe). The evaluation was aimed at finding out the performance of the laboratory borers subjected&nbsp; to six-month interval of gene infusion in comparison with wild F1 generation of the same species&nbsp; collected from the field. One hundred (100) maize seedlings were grown on plastic pots of 5 by 5 cm and&nbsp; of 12 cm-height. The maize seedlings were infested with five first instar larvae on eight plants replicated&nbsp; four times for each borer ecotype. The wild ecotypes were collected from two different localities for&nbsp; comparison with eight-year old laboratory reared borers. Foliar damage, tunnel length on the maize&nbsp; stems and the recovered number of C. partellus larvae from the maize plants were used as the&nbsp; parameters for quality measure of the borer ecotypes. The laboratory-reared stem borer species had&nbsp; been subjected to frequent six-month gene-infusion interval from the wild. The results indicated feedvoracity drop of 3.8 and 21.5% for stem and foliar damage on the laboratory borer ecotype. The study&nbsp; established the need for continuous gene infusion to maintain high quality maize stem borer species as&nbsp; test organisms.&nbsp; &nbsp; Key words: Chilo partellus, quality insects, insect rearing, maize genotypes.&nbsp;

Mechanisms and Sources of Resistance in Tropical Maize Inbred Lines to Chilo partellus Stem Borers

Developing maize with durable resistance to maize stem borers could be enhanced by identifying genotypes with different mechanisms of resistance and pyramiding the resistances into high yielding genotypes. This study was carried out on 120 CIMMYT tropical maize inbred lines to identify the most important mechanisms of resistance that could be used to discriminate the germplasm into resistant or susceptible categories. The experiment was laid in an α-lattice design, and replicated three times during the 2011/12 seasons. Traits measured were leaf toughness, stem penetrometer resistance, trichome density, stem sugar content, leaf damage, number of stem exit holes and stem cumulative tunnel length. A selection index was computed and categorized the 120 inbred lines into 33 resistant, 29 moderately resistant, 31 moderately susceptible and 27 susceptible. The most resistant lines were those derived from the CIMMYT multiple borer-resistant populations with CKSBL10039 being most resistant and CML395 most susceptible with indices of 0.49 and 1.84, respectively. Trichome density, leaf toughness and stem sugar content in that order were the most important traits in discriminating the lines into resistance and susceptible categories. More research is needed to classify the specific types of trichomes and sugars present in both resistant and susceptible inbred lines.

Maize stemborers distribution, their natural enemies and farmers’ perception on climate change and stemborers in southern Togo

Objective: The objectives of this study were to (i) assess the importance of the different stemborer species and their associated natural enemies on maize, and (ii) evaluate cereal producers’ perception on the effect of the current climate variability, on the maize stem and ear borers and their mitigation strategies to alleviate the impact of climate change on their cropping system. Methodology and results: Surveys were conducted in 2012 during the long cropping season lasting from March to July and the short one from September to October in southern Togo, to determine geographic distribution, relative importance of lepidopterous stemborers and their parasitism by natural enemies on maize. A questionnaire was introduced to evaluate cereal farmers’ perception of climate change and its effects on maize stem and ear borers. Of the total borer species recovered, the most abundant was Sesamia calamistis Hampson (Lepidoptera: Noctuidae) (76.02%), followed by Busseola fusca Füller (Lepidoptera: Noctuidae) (21.71%) and then Eldana saccharina Walker (Lepidoptera: Pyralidae) (2.27%). The borers’ abundance was affected by the agroecological zones and cropping seasons. Eldana saccharina was found in Zio and Yoto in coastal zone whereas B. fusca was recorded only in Yoto. Sesamia calamistis was the only species found in all the surveyed agroecological zones (III, IV and V). Fields were infested by all borer species at 34.4% and 83.3% in the long and short cropping seasons respectively. The percentage of infested plants ranged from 0 to 72% in the first cropping season, and 33 to 95% in the second cropping season. The borer densities varied from 0 to 3 larvae per plant in the long cropping season and 1 to 8 larvae per plant in the short cropping season. The egg parasitoid Telenomus busseolae Gahan (Hymenoptera: Scelionidae) was identified as the most important with a high natural parasitism rate of 82% on S. calamistis. The main larval parasitoid recorded was Sturmiopsis parasitica Curan (Diptera: Tachnidae) with mean parasitism ranged of between 0 and 8%. Beauveria bassiana (Bals.) Vuill. (Deuteromycotina: Hyphomycetes) infection rate vary from 0 to 5%.of borers’ larvae. Data on farmer’s perception showed that all producers recognized stem and ear borers and their damages. However, they perceive climate change effects differently by high temperatures, rains irregularity, floods, strong winds and to a lesser extent the proliferation of new pests such as termites (Isoptera), Zonocerus variegatus (L) (Orthoptera: Pyrgomorphidae) and Cicadulina spp. (Hemiptera: Cicadellidae). Adaptation strategies practiced by farmers are the choice of early maturing crop varieties, the spacing of sowing period and the crop diversification. Conclusion and application of funding: From these results, we conclude that S. calamistis, E. saccharina, and B. fusca and their associated natural enemies are present in all agroecological zones of southern Togo. These findings could serve as baseline data for further studies. Key words: Climate change, ear borers, incidence, maize, parasitism, severity, stem borers.

Distribution and extent of Cotesia Flavipes Cameron (Hymenoptera: Braconidae) Parasitism in Northeastern Ethiopia.

The distribution and extent of parasitism of Cotesia flavipes Cameron (Hymenoptera: Braconidae) on stem borer species attacking maize and sorghum were assessed in three zones of northeastern Ethiopia. Cotesia flavipes was found to be the key larval parasitoid of cereal stem borer species in all areas surveyed. This parasitoid has been introduced into several African countries for the control of Chilo partellus in maize and sorghum, but it has never been released in Ethiopia. The survey results indicated that the distribution and extent of parasitism of Cot. flavipes followed the distribution and severity of its suitable host, C. partellus. A Cotesia flavipes parasitism rate of between 33% and 82% was recorded in sub-moist warm (lowland) AEZs of all zones. In contrast, a parasitism rate of less than 6% was recorded in moist, cool highland areas where Busseola fusca was the predominant species. Cotesia flavipes caused lower rate of parasitism on stem borers in maize (up to 72%) than that of sorghum (up to 82%) in the three zones. In summary, high rates of parasitism of Cot. flavipes were recorded in lowland areas where C. partellus was the dominant borer species and low rates of parasitism were recorded in highland areas where B. fusca was the predominant species. Cotesia flavipes caused the highest parasitism (82%) on C. partellus. This result verified that Cot. flavipes contributed to the reduction of C. partellus population in lowlands, regardless of the zone, and its rate of parasitism varied between crop stages, crop types, elevations, host, and host stages. Findings of this study have particularly relevant information on the contribution of Cot. flavipes to the population reduction of stem borers, time or stage of its occurrence in relation to host stages and crop stages, and its distribution in relation to the availability of a suitable host across each zone. In conclusion, this larval parasitoid plays an important role in reducing stem borer populations and can be used as one component of integrated stem borer management in northeastern Ethiopia.