Stem Borer Species Research Articles

Habitat opening fostered diversity: impact of dispersal and habitat‐shifts in the evolutionary history of a speciose afrotropical insect group

The opening of habitats associated with the emergence of C4 grasslands during the Neogene had a massive influence on the evolution of plant and animal communities. Strikingly, the impacts of grassland expansion on species diversification in Africa, where the largest surface of grasslands and savannas in the world is located, are not well understood. To explore the impact of habitat opening, we investigate the evolution of noctuid stemborers, a group of moths mostly associated with open habitats, and whose diversity is centered in the Afrotropics. We generate a dated molecular phylogeny for ca 80% of the known stemborer species, and assess the role of habitat opening on the evolutionary trajectory of the group through a combination of parametric historical biogeography, ancestral character state estimation, life history traits and habitat‐dependent diversification analyses. Our results support an origin of stemborers in Southern and East Africa ca 20 million years ago (Ma), with range expansions linked to the increased availability of open habitats to act as dispersal corridors, and closed habitats acting as potent barriers to dispersal. Early specialization on open habitats was maintained over time, with shifts towards closed habitats being rare and invariably unidirectional. Analyses of life history traits showed that habitat changes involved specific features likely associated with grassland adaptations, such as variations in larval behavior and color. We compare these findings to those previously inferred for an Afrotropical butterfly group that diversified roughly in parallel with the stemborers but distributed predominantly in closed habitats. Remarkably, these two groups show nearly opposite responses in relation to habitat specialization, whether in terms of biogeographical patterns, or in terms of rates of transition between open and closed habitats. We conclude that habitat opening played a major role in the evolutionary history of Afrotropical lineages through dispersal and adaptation linked to habitat shifts.

Prospecting for fine scale establishment of exotic stem borer pupal parasitoid (Xanthopimpla stemmator Thunberg) in Kenya

Lepidopteran stem borers are an important constraint to cereal production in Sub- Saharan Africa. The exotic Chilo partellus (Swinhoe) is one of the most economically important stem borer pest causing extensive losses on cereal crops in Kenya. This pest has also displaced indigenous species of stem borers while expanding its range in warm, mid and high altitude areas. In order to exert control on various developmental stages of this pest, both Cotesia flavipes Cameron (larval endoparasitoid) and Xanthopimpla stemmator Thunberg (pupal endoparasitoid) were imported and released in 2002 in the Eastern region of Kenya. This study was conducted to assess the establishment status, spread and impact of X. stemmator on C. partellus following its release in Kenya. Stem borer sampling was done on farms where the biocontrol agents had been released and on transects radiating outwards from them every 15km to assess spread. A total of 100 maize plants were inspected for stem borer infestation and destructive sampling done on 10 maize stems per farm to collect immature stem borer stages. Emerging parasitoids and adult moths were identified, counted and recorded. Results of this study showed that C. partellus was the most dominant stem borer species (constituted 71.2%) followed by Sesemia calamistis and Busseola fusca (26.0 and 2.8% respectively). A decrease in overall stem borer infestation (22.47±7.42%) with no significant difference across distances from parasitoid release points (F=0.4; df=3, 51; p>0.05) was also recorded. Seven parasitoid species were recovered, the most abundant being C. flavipes and this coupled with a significant increase in parasitism (25.27±3.27%) (V=1213, p˂0.05) from pre-release levels. The parasitoid of interest, X. stemmator was not recovered. This suggests a failure to establish though there is need to sample alternative hosts before this is declared. Key words: Classical biological control, lepidoptera, pupal parasitoid, post release survey, Xanthopimpla stemmator, Eastern Kenya

Spatial and agronomic stage distribution dynamics of maize stem borers (Lepidoptera) in the Agricultural development Zone B of Niger State, Nigeria

Maize farmers in Nigeria have been facing challenges as efforts towards the cultivation of maize is seriously hampered by insect pest infestation in maize fields, of which stem borers are a major culprit. The study was carried out to identify the species of stem borers present and their abundance in Agricultural development Zone B of Niger State. Farm sites located in Beji, Chanchaga, Paiko and Shanu, were selected and sampled for stem borers, during vegetative, reproductive and harvest stages of the field maize crops. Identification was done using standard taxonomic keys. The results indicated the presence of three species of stem borer belonging to three families. A species each from Noctuidae, Crambidae and Pyralidae consisting of Busseola fusca (n = 1639, 68.24%), Chilo partellus (n = 160, 6.66%) and Eldana saccharina (n = 603, 25.10%) respectively. Generally, all sites had two species of the stem borer (B. fusca and E. saccharina) present in all growth stages of the maize plant during the destructive sampling with the exception of Chilo partellus that was rarely found; occurring only in one site (Beji), all amounting to a total of 2402 stem borers collected during the study period. Among all the growth stages of the maize plants in all sampled sites the level of infestation varied significantly (p< 0.05), in an increasing order: vegetative stage < reproductive stage < harvest stage of the maize plants. The findings of this study suggest that there is a serious stem borer pest infestation in the maize farms of Agricultural development Zone B of Niger state that could pose threats to maize (Zea mays) production in the area; thus, requiring urgent interventions on the parts of all stakeholders.

Influence of Abiotic Factors on the Population Dynamics and Species Composition of Stem Borer Complex in Rice Ecosystem

A field experiment was carried out at the Murjhad Research Farm, College of Agriculture, Balaghat in Madhya pradesh during Kharif 2022 and Kharif 2023 to ascertain the population dynamics of stem borer complex, their relative abundance and correlation with abiotic factors in order to propose ecologically and financially feasible measures. Results pertaining to the dynamics of species composition of stem borers of rice reveal that all the three species of stem borer of rice viz., yellow stem borer, Scirpophaga incertulas (Walker), pink stem borer, Sesamia inferens (Walker), white stem borer, Scirpophaga innotata (Walker) were prevalent during the crop season. The pooled data of the total population of stem borer complex observed during the 30th SMW was 8.0 larvae/ 20 hills attaining two peaks, the first peak during the 36th SMW (69.0 larvae/ 20 hills) and the second peak during the 42nd SMW (96.0 larvae/ 20 hills) and thereafter, the population started decreasing and reached 65.0 larvae/ 20 hills during the 43rd SMW and it disappears at the time of harvest. The per cent dead heart incidence was first observed during the 30th SMW (2.43% dead hearts) with its peak during the 36th SMW (14.84% dead hearts) and thereafter, it started decreasing and reached 5.06 per cent dead hearts during the 38th SMW and further, it disappears. The per cent white ears incidence was first observed during the 37th SMW (1.30 % white ears) with its peak during the 42nd SMW (21.52% white ears) and thereafter, it started decreasing and reached 9.24 per cent white ears during the 43rd SMW and further, it disappears. The pooled data revealed that a total of 654.5 larvae stem borer complex were observed throughout the crop growth. Among them, 467 larvae of Scirpophaga incertulas were observed comprising 71.35 per cent, Sesamia inferens population was 110.0 larvae comprising 16.81 per cent and Scirpophaga innotata population was 77.5 larvae comprising 11.84 per cent among the stem borer complex. The data revealed that population of Scirpophaga incertulas was found significantly positive correlated (r= 0.617) with sunshine hours and significantly negative correlated with minimum temperature (r= -0.553). The population of Sesamia inferens was found significantly positive correlated (r= 0.613) with sunshine hours. The larval population of Scirpophaga innotata was not found significant with any weather parameter. The per cent dead heart was found significantly positive correlated with minimum temperature, morning relative humidity and evening humidity (r= 0.550, 0.662 and 0.633, respectively). The per cent white ear was found significantly positive correlated with maximum temperature and sunshine hours (r= 0.535 and 0.627, respectively) and significantly negative correlated with minimum temperature, morning relative humidity, evening relative humidity and evaporation (r= -0.658, -0.689, -0.703 and 0.819, respectively).

Species Investigation of Rice Stem Borers and Its Parasitoids on Fallowing Rice Fields at Karawang, Indonesia

<p>Rice stem borers (RSB) cause the same damage symptoms and occur through the season and time. During the off-season for rice, these stem borers are not well-known. The research aims to determine the effect of fallowing rice on the presence of rice stem borers and their parasitoids, the potential for RSB infestation, and their parasitoid on subsequent rice seedlings in nurseries at Karawang Regency, West Java. Several variables are observed, including the number of rice stem borer larvae on stubbles, egg masses, the percentage of parasitized eggs, and the number of adults of rice stem borer in nurseries. The results show that species of rice stem borer on the fallow rice are <em>Scirpophaga incertulas</em> and <em>Sesamia inferens</em>. The population of <em>S. incertulas</em> is significantly higher on long rice fallow. The height of the paddy stubble at the two locations is not very different. However, the infested stubble in the short fallow period is higher than those in the long fallow. Eggs of <em>S. incertulas</em> whose high percentage hatched and parasitized, are primarily found in nurseries of areas with long fallow. There are three species of parasitoids identified.</p>

Progress in developing and deploying drought-tolerant and insect-pest resistant climate-resilient droughtTEGO® and TELA® maize varieties

Currently, drought stress and associated insect-pest damage pose a huge threat to food and nutrition security for over 300 million people in Africa who depend on maize as their main food source. Recurrent drought events cause an annual 17 to 25 percent yield loss of maize in Africa [1]. Compounding the impact of drought, is the ravaging effect of insect-pests infestation on maize production, especially for pests whose population pressure is highly triggered under dry conditions. The crop under weakened conditions created by drought stress and pest effect further becomes constrained biologically and physiologically, thus limiting the crop’s ability to use already limited water and nutrients from the soil. The major insect pests of maize in Africa are fall armyworm (FAW, Spodoptera frugiperda) and various stem borer species (Spotted stem borer (Chilo partellus), African stem borer (Busseola fusca), and the pink stemborer (Sesamia Calamistis). For instance, in Kenya alone, an average of 13 percent or 400,000 tons of maize is lost to stem borer, which is equivalent to the annual maize imports, valued at USD 90 million [2]. The FAW, a transboundary pest, first observed in the continent in 2016, is a maize pandemic that if not controlled adequately, could potentially destroy up to 20 million metric tons of maize annually, enough to feed 100 million people in Africa [3].

Old and new association of Cotesia icipe (Hymenoptera: Braconidae) with alien invasive and native Spodoptera species and key stemborer species: Implication for their management.

The production of maize in Africa is hindered by a myriad of biotic challenges, key among them being invasive and native lepidopteran stemborers. The recent invasion of the continent by Fall armyworm, Spodoptera frugiperda has further exacerbated the situation. Fortunately, Cotesia icipe was found to be very promising against S. frugiperda. However, the co-occurrence and interaction between S. frugiperda and the stemborers (Busseola fusca, Sesamia calamistis, and Chilo partellus) in maize agroecosystem may jeopardize the efficiency of C. icipe as a biocontrol agent of S. frugiperda. This study investigated the performance of C. icipe on S. frugiperda, Spodoptera littoralis and the stemborers. Specifically, the preference and acceptability of C. icipe to the host insects; physiological suitability of the hosts for its development, and effect of these hosts on fitness parameters of the offspring were assessed. Cotesia icipe accepted all the tested hosts albeit with higher preference to the Spodoptera species than stemborers under multiple choice tests. Also, the highest parasitism of up to 97% was recorded on S. frugiperda compared to that on the stemborers of 43% in B. fusca. Moreover, physiological suitability and fitness traits (except for percent female offspring) varied with host species, again being optimal on the Spodoptera species. Cotesia icipe demonstrated strong potential to control S. frugiperda in maize due to its high affinity for parasitisation and developmental success in this host; and despite its non-specific parasitisation, the presence of other hosts may not prevent its maximum control of S. frugiperda. This article is protected by copyright. All rights reserved.

Abundance and Infestation of Rice Stem Borer in North Malaysia

The abundance and infestation of rice stem borer were monitored in MADA regions with the influence of weather parameters. The determination of the rice stem borer percentage infestation was recorded by dead heart (DH) and whitehead (WH) symptoms. In four regions of MADA area observations, a higher infestation of rice stem borer was observed during rice planting season one (7.1%) compared to rice planting season two (3.9%) on average. Both damage symptoms of the rice stem borer, DH, and WH were observed higher during the rice planting season one. The highest infestation of rice stem borer during season one was observed in Pendang with 18.60%. From the weather parameters recorded, a high infestation of rice stem borer occurred at 80.0% (RHmax), 8.2 °C of temperature differences (Tdiff), and a lower amount of rainfall (0.6 mm). The high infestation in Pendang in season one was influenced by the lower value of RH, higher range of temperature, and lower amount of rainfall compared to season two. Chilo polychrysus was the most abundant species of rice stem borer found in Region 1 and Scirpophaga incertulas were abundantly found in Region 2, 3, and 4.

Cannibalism and intraguild predation involved in the intra- and inter-specific interactions of the invasive fall armyworm, Spodoptera frugiperda, and lepidopteran maize stemborers

Cannibalism and intraguild predation can play important roles in determining spread and survival or death of organisms which share the same resource. However, the relationship between cannibalism and intraguild predation, and the costs and benefits of such behaviours, is difficult to establish within insect communities, and little is known about how such behaviours are affected by invasive species. The present study was aimed at assessing the interactions between larvae of fall armyworm (Spodoptera frugiperda) and maize stemborers (native to Africa, Busseola fusca, and Sesamia calamistis and native to India, Chilo partellus) in relation to cannibalism and intraguild predation when they utilize the same resource. Experiments involving treatments with either single species of S. frugiperda or any of the stemborers or pairwise species combinations with S. frugiperda were conducted under laboratory conditions. The experimental insect larvae were reared on maize leaves and monitored until the last developmental stage where cannibalism and/or intraguild predation, larval survival, and relative growth rate were recorded. Results of the intraspecific interaction indicated that S. frugiperda exhibited cannibalism to a larger degree than the stemborers species, especially at the late instars. The higher cannibalism trait in S. frugiperda turned, however, to competitive advantage as it led to a higher degree of intraguild predation when they cohabit with stemborer species and allowed FAW to gain a greater relative growth rate. Overall, interactions with FAW are detrimental for stemborer species and may be an important factor to explain the invasive success of S. frugiperda. Such knowledge is essential to understand the mechanisms behind ecological interactions between pests with overlapping niches in the field and in designing successful integrated pest management strategies.

Phylogenetics, integrative taxonomy and systematics of the Sesamia cretica species group (Lepidoptera: Noctuidae: Apameini: Sesamiina), with the description of 21 new species from the Afrotropical region

Summary In this study, 31 species of noctuid stemborers belonging to the genus Sesamia Guenée, 1852 (Lepidoptera: Noctuidae: Noctuinae: Apameini: Sesamiina) are reviewed. All these species are assigned to the Sesamia cretica group sensu Tams & Bowden (1953). Based on genitalic characters, several subgroups are hereby defined. Nine species belong to a species complex defined as the Sesamia albivena Hampson, 1902 subgroup; it consists of S. albivena, S. mocoensis Tams & Bowden, 1953, n. stat., S. sudanensis Tams & Bowden, 1953, n. stat. S. taenioleuca (Wallengren, 1863), and five new species that are described (S. aethiopica Le Ru n. sp. from Ethiopia, S. kafulo Le Ru n. sp. from Botswana and Zambia, S. kavirondo Le Ru n. sp. from Kenya and Uganda, S. maloukou Le Ru n. sp. from Republic of Congo, and S. soyema Le Ru n. sp. from Ethiopia). Four species belong to a species complex defined as the Sesamia cretica subgroup; this encompasses S. cretica, S. rufescens Hampson, 1910, and two new species that are described (S. ihambane Le Ru n. sp. from Mozambique and Tanzania and S. kikuyuensis Le Ru n. sp. from Kenya); two new synonyms are introduced for Sesamia cretica: Nonagria uniformis Dudgeon, 1905 n. syn. and Sesamia griselda Warren, 1913, n. syn. Ten species belong to a species complex defined as the Sesamia fuscifrontia Hampson, 1914 subgroup; this includes S. fuscifrontia, S. geyri (Strand, 1915) and eight new species that are described (S. babati Le Ru n. sp. from Tanzania, S. babessi Le Ru n. sp. from Cameroon and Zambia, S. mabira Le Ru n. sp. from Uganda, S. nangaensis Le Ru n. sp. from Cameroon and Republic of Congo, S. rungwa Le Ru n. sp. from Tanzania, S. simillima Le Ru n. sp. from Benin, Cameroon, Kenya and Uganda, S. taveta Le Ru n. sp. from Kenya and S. ulaukae Le Ru n. sp. from Ethiopia). One species belongs to a species complex defined as the Sesamia salama Le Ru n. sp. subgroup; this consists of S. salama Le Ru n. sp. from Kenya and another undescribed Sesamia species from South Africa. One species belongs to a species complex defined as the Sesamia viettei Rungs, 1954 subgroup. Six species belong to a species complex defined as the Sesamia wiltshirei Rungs, 1963 subgroup; this groups S. wiltshirei and five new species that are described (S. djenoensis Le Ru n. sp. from Republic of Congo, S. inexpectata Le Ru n. sp. from South Africa and Zambia, S. lefini Le Ru n. sp. from Republic of Congo, S. echinochloa Le Ru n. sp. from Botswana, Kenya, Mozambique, South Africa, Tanzania and Zambia and S. rindini Le Ru n. sp. from Tanzania). A supplemental description of the previously described species is also provided. Novel host plant records are also provided for 11 species of the S. cretica group. To complement the morphological study, both phylogenetic and molecular species delimitation analyses were carried out on a multimarker (four mitochondrial and two nuclear genes) molecular dataset encompassing 144 specimens representing 35 species (including 25 species from the S. cretica group). Molecular analyses provide a well-supported phylogenetic framework for the species of interest, which are all recovered monophyletic. Molecular species delimitation analyses also support the species status of almost all sampled species. Interestingly, the inferred tree indicates that the S. cretica group and the S. fuscifrontia subgroup are both paraphyletic; this indicates that, while highly informative, the chosen genitalic characters in Sesamia are not all synapomorphies.

Competitive Plant-Mediated and Intraguild Predation Interactions of the Invasive Spodoptera frugiperda and Resident Stemborers Busseola fusca and Chilo partellus in Maize Cropping Systems in Kenya.

Simple SummaryInvasion of fall armyworm led to co-inhabitation with resident stemborers in maize cropping systems in Kenya. As a result, exploitative and interference intraguild interactions occur between these lepidopteran pests. However, mechanistic insights into these interactions are poorly understood. These interspecific interactions may impact population dynamics and niche displacement of these pests in maize crops. Fall armyworm dominates resident stemborers in maize crops where they co-exist. This is due to plant-mediated and predation competitive advantages exhibited by fall armyworm over stemborers. Understanding such interactions provides crucial information for designing pest management strategies for these lepidopteran pests.Following its recent invasion of African countries, fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), now co-exists with resident stemborers such as Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Crambidae) causing severe damage to maize crops. Due to niche overlap, interspecific interactions occur among the three species, but the mechanisms and degree remain unclear. In this study, we assessed plant-mediated intraspecific and interspecific interactions, predation in laboratory and semi-field settings, and larval field occurrence of S. frugiperda and the two stemborer species. Larval feeding assays to evaluate competitive plant-mediated interactions demonstrated that initial S. frugiperda feeding negatively affected subsequent stemborer larval feeding and survival, suggesting induction of herbivore-induced mechanisms by S. frugiperda, which deters establishment and survival of competing species. Predation assays showed that, at different developmental larval stages, second–sixth instars of S. frugiperda preyed on larvae of both B. fusca and C. partellus. Predation rates of S. frugiperda on stemborers was significantly higher than cannibalism of S. frugiperda and its conspecifics (p < 0.001). Cannibalism of S. frugiperda in the presence of stemborers was significantly lower than in the presence of conspecifics (p = 0.04). Field surveys showed a significantly higher number of S. frugiperda larvae than stemborers across three altitudinally different agroecological zones (p < 0.001). In conclusion, this study showed that the invasive S. frugiperda exhibited a clear competitive advantage over resident stemborers within maize cropping systems in Kenya. Our findings reveal some of the possible mechanisms employed by S. frugiperda to outcompete resident stemborers and provide crucial information for developing pest management strategies for these lepidopteran pests.

Taxonomic Studies on Graminaceous Stem Borers from North India

Thirteen species of stem borers attacking graminaceous crops, belonging to five genera viz. Chilo Zincken, 1817; Scirpophaga Treitschke, 1832; Bissetia Kapur, 1950; Emmalocera Ragonot, 1888; Sesamia (Guenee, 1852) have been redescribed with current valid names, synonyms, authors, distribution, and host plants. The specimens were identified from characters of the genitalia such as shape of the uncus, gnathos, valva, projections of the costa or tegumen, and shape of aedeagus. The genitalia of Emmalocera aurifusellus (Walker, 1866) is described here for the first time. Photographic illustrations for each species which includes the male and female habitus, and the genitalia of both sexes and diagnostic keys are provided.

Performance of Bt maize event MON810 in controlling maize stem borers Chilo partellus and Busseola fusca in Uganda

Stem borers are major insect pests of maize in Uganda. A study was conducted in 2014–2016 to assess the performance of Bt hybrids expressing Cry1Ab (event MON810) against the two major stem borer species in Uganda – the African stem borer (Busseola fusca) and the spotted stem borer (Chilo partellus) – under artificial infestation. The study comprised 14 non-commercialized hybrids, including seven pairs of Bt and non-Bt hybrids (isolines), three non-Bt commercial hybrids and a conventional stem borer resistant check. All stem borer damage parameters (leaf damage, number of internodes tunneled and tunnel length) were generally significantly lower in Bt hybrids than in their isolines, the conventionally resistant hybrid, and local commercial hybrids. Mean yields were significantly higher by 29.4–80.5% in the Bt hybrids than in the other three categories of non-Bt hybrids. This study demonstrated that Bt maize expressing Cry1Ab protects against leaf damage and can limit entry of stem borers into the stems of maize plants, resulting in higher yield than in the non-transgenic hybrids. Thus, Bt maize has potential to contribute to the overall management package of stem borers in Uganda.

Influence of abiotic factors on stem borer incidence and species distribution in rice (Oryza sativa L.)

Aim: To evaluate the effect of abiotic factors such as temperature, relative humidity, wind velocity, sunshine hours and rainfall on the distribution and relative abundance of stem borer species in rice ecosystem. Methodology: Seasonal incidence of stem borer species was monitored using light trap catches and were correlated with the weather parameters. The relative abundance of stem borer species during Kharif and Rabi was estimated based on light trap catches and larval incidence. Results: Seasonal incidence revealed the occurrence of three stem borer species (yellow stem borer, pink stem borer and dark headed borer) populations in rice ecosystem. Yellow stem borer was found to dominate in rice ecosystem during Kharif, (80.61%) whereas during Rabi, pinkstem borer was found to be dominant (72.60%) than yellow stem borer (21.92%) and dark headed borer (5.48%). Weather parameters such as temperature, rainfall and wind velocity negatively influenced the occurrence of stem borer species in rice, whereas relative humidity and sunshine hours had positive effect. Regression analysis revealed the increased effect of abiotic factors such as temperature, relative humidity and wind velocityon the population of pink stem borer against yellow stem borer and dark headed borer. Interpretation: The present study reveals that, the change in weather parameter during seasons, such as temperature (25 - 27°C), relative humidity (69 - 80 %) and wind velocity (3 - 4 km hr-1) increased the fitness of pink stem borer species population than yellow stem borer and dark headed borer species in rice ecosystem, which was evidenced by the occurrence and relative abundance of pink stem borer population during Kharif 2018 and Rabi 2019 respectively.

Natural parasitism of maize stemborers, Sesamia spp. (Lepidoptera: Noctuidae) eggs by Trichogramma evanescens (Hymenoptera: Trichogrammatidae) in Southeastern Turkey

Maize, Zea mays L., is currently among the leading cultivated crops in Turkey. Several lepidopteran stemborer species especially, Sesamia nonagrioides Lefèbvre and S. cretica Lederer (Lepidoptera: Noctuidae) may cause high maize yield losses. This study is the first to report parasitism of Sesamia spp. eggs by Trichogramma evanescens (Hymenoptera: Trichogrammatidae) in Southeastern Turkey. During our extensive 3-years region-wide survey program (2018-2020), we collected Sesamia spp. eggs laid between leaf sheets and cobs/stalks. T. evanescens adults hatched from the host eggs collected from two locations in Diyarbakır: one in the central county (L10) and the other in Bismil county (L11). The discovery efficiency, parasitism efficiency, and parasitoid impact indexes of T. evanescens were 77.5%, 38.92%, and 32.87% in L10 and 50.0%, 33.45%, and 12.42% for L11, respectively. Sesamia spp. eggs collected from other counties of Diyarbakır province and other provinces such as Batman, Mardin, and Şanlıurfa did not yield in T. evanescens emergence. To our best knowledge, this study is the first to report the presence of T. evanescens in Southeastern Turkey. Possible factors involved in the restriction of T. evanescens are discussed. Special attention should be devoted to increase the potential of conservative biological control strategies to support egg parasitoids.

Komposisi Spesies Penggerek Batang Padi dan Parasitoid Telurnya pada Ketinggian Tempat yang Berbeda

Composition of Rice Stem Borer Species and Their Egg Parasitoids at Different Altitudes. Rice stem borer is one of the main pest of rice plants that always percolating and attack plants in the field. The pests can result in damage to plants and lost of the grain from season to season. The aim of this research is to know composition and dominance rice stem borer species and role of their eggs parasitoid at an altitude of different places. Research is done by survey based on the height of different altitude in rice plants two weeks after cropping up until eleven weeks after planting. Research conducted from April until August 2019 in rice field that belonging to farmers at Subak Cemagi Let, Cemagi Village and Subak Teba, Mengwi village, Badung regency, Bali province. Subak Cemagi Let are at an altitude of 15 meters above sea level whereas Subak Teba are at an altitude of 300 meters above sea level. Identification of Rice stem borer larvae and their eggs parasitoid done in Pest Laboratory, Agriculture Faculty of Udayana University. Found three species rice stem borer in the height 15 mdpl namely Scirpophaga incertulas; Sesamia inferens dan Chilo suppressalis, whereas in the height 300 mdpl found four species namely Scirpophaga incertulas, Sesamia inferens, Chilo suppressalis, dan Chilo polychrysus. S. incertulas was the most dominant at the two different altitude. Three species of eggs parasitoid that have role to suppress the development of rice stem borer at the different altitude namely Tetrastichus schoenobii, Telenomus rowani dan Trichogramma japonicum. T. schoenobii was the most dominant to suppress rice stem borer populations.

Impact of an Exotic Invasive Pest, Spodoptera frugiperda (Lepidoptera: Noctuidae), on Resident Communities of Pest and Natural Enemies in Maize Fields in Kenya

The interactions among insect communities influence the composition of pest complexes that attack crops and, in parallel, their natural enemies, which regulate their abundance. The lepidopteran stemborers have been the major maize pests in Kenya. Their population has been regulated by natural enemies, mostly parasitoids, some of which have been used for biological control. It is not known how a new exotic invasive species, such as the fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera, Noctuidae), may affect the abundance and parasitism of the resident stemborers. For this reason, pest and parasitism surveys have been conducted, before and after the FAW invaded Kenya, in maize fields in 40 localities across 6 agroecological zones (AEZs) during the maize-growing season, as well as at 3 different plant growth stages (pre-tasseling, reproductive, and senescence stages) in 2 elevations at mid-altitude, where all maize stemborer species used to occur together. Results indicated that the introduction of the FAW significantly correlated with the reduction of the abundance of the resident communities of maize stemborers and parasitoids in maize fields; moreover, the decrease of stemborer density after the arrival of FAW occurred mostly at both reproductive and senescent maize stages. It also suggests a possible displacement of stemborers by FAW elsewhere; for example, to other cereals. However, since this study was conducted only three years after the introduction of the FAW, further studies will need to be conducted to confirm such displacements.

An Assessment of the Abundance and Species Richness of Lepidopteran Stemborer Communities in Selected Natural Habitats in the Eastern Cape and KwaZulu-Natal, South Africa

Invasion of crops by stemborers previously known in natural vegetation only requires close monitoring for early detection of stemborer exchange between the habitats. This in turn demands up-to-date knowledge about the diversity of stemborers in natural habitats. The current list of known stemborers in South Africa includes 49 species associated with 65 wild host plant. The Eastern Cape and KwaZulu-Natal biogeographic regions received little coverage in earlier studies. This study sought to fill this knowledge gap. We conducted surveys from 14 November 2014 to 18 March 2015 in the Eastern Cape and KwaZulu-Natal biogeographic regions. Potential host plants in families Poaceae, Cyperaceae, and Typhaceae were dissected in the field, stemborer life stages collected, reared on artificial diet, and identified to the lowest possible taxonomic level. Thirty-three species belonging to Crambidae, Noctuidae, Phycitidae, Pyralidae and Tortricidae were recovered from 27 host plant species. Twenty-four species were recorded in Eastern Cape and 28 species in KwaZulu-Natal. The Chao 1 asymptotic species richness estimator predicted 3 and 5 more species for the biogeographic regions indicating an equitably complete species inventory of the study area. Fifteen species collected in this study are part of the existing inventory, and 19 are first records on the various host plants. The new records expand the list of stemborer species in South Africa from 49 to 68. The main factors influencing diversity were endemism, the number and disproportionate abundance of common and rare species.

Genetics of dual resistance to african stem borer, busseola fusca and spotted stem borer, Chilo partellus in sorghum

African stem borer, Busseola fusca Fuller (Noctuidae) and spotted stem borer, Chilo partellus Swinhoe (Crambidae) cause more than 40 % of grain yield loss in cereals and bothpests co-exist in mid-altitudes in Kenya. Development of sorghum with dual resistance to B. fusca and C. partellus has been difficult due to the inadequate understanding of inheritance of resistance traits to the two species. The objective of this study was to investigate the genetics of dual resistance to the two insect species in sorghum. Thirty sorghum populations derived from crossing sorghum lines with varying levels of resistance to the two insect species were studied. The experiments were conducted in two separate sites at Embu and Kiboko in Kenya with two replications per site. North Calorina Design II mating design was used. Artificial infestation with first instar neonates of each pest species was done at 30 days after planting in both sites. Data collected included sorghum damage due to the two borer species and agro-morphological traits. Genetic analyses were performed using line x tester method using Genstat statistical software. Data analyses revealed that general combining ability (GCA) and specific combining ability (SCA) effects were significant for foliar and stem damage traits, indicating that additive and non-additive gene effects conditioned resistance to B. fusca and C. partellus. Sorghum lines ICSA 464, ICSB 474, ICSB 464 and ICSA 472 and ICSB 473 exhibited desirable high negative GCA effects to B. fusca and C. partellus. These parents could be used in development of sorghum with dual resistance to B. fusca and C. partellus thus contributing to sustainable integrated management of these two stem borer species in sorghum via host plant resistance management.

A system dynamics model for pests and natural enemies interactions

Stemborers (Busseola fusca, Sesamia calamistis and Chilo partellus), the fall armyworm (Spodoptera frugiperda) and associated parasitoids constitute an interacting system in maize fields in Kenya. This work aims at developing and evaluating models that represent the evolution of those interactions by applying system thinking and system dynamics approaches with its archetypes [causal loop diagram (CLD), reinforcing (R) and balancing (B)] to analyse the population of these multi-species systems. The software Vensim PLE 8.0.9 was used to implement the models and carry out the simulations of single- and multi-species systems. The results showed that when a single pest species with its associated parasitoids interact with the host plant, the species was able to establish and sustain by cyclical relationship between populations of the pest and the associated parasitoids. However, in multi- pest species systems, dominance of S. frugiperda and C. partellus over B. fusca and S. calamistis was observed, but without extinction. However, there was a likelihood for B. fusca being displaced by C. partellus. Overall, the models predict the co-existence of fall armyworm with stemborer species as an additional pest of maize in Africa that need to be considered henceforth in designing IPM strategies in maize.