The role of wild grasses in the management of lepidopterous stem-borers on maize in the humid tropics of western Africa

Sites in the humid forest of Cameroon and the derived savanna of Benin were selected to evaluate the effect of planting border rows of wild host plants on lepidopterous stem-borer infestations and on maize yield. Grass species were chosen that in surveys and greenhouse trials were highly attractive to ovipositing female moths but with offspring mortality of close to 100%, thus acting as trap plants. In Cameroon, elephant grass Pennisetum purpureum Moench significantly lowered infestations of Busseola fusca (Fuller), Sesamia calamistis Hampson and Eldana saccharina Walker and increased yields of maize though the differences were not significant during all three cropping seasons. In 1998 in Benin, the only grass tested, Pennisetum polystachion L., significantly increased parasitism of mainly S. calamistis eggs by Telenomus spp. and larvae by Cotesia sesamiae Cameron and reduced numbers of the cob-borer Mussidia nigrivenella Ragonot. In 1999, three grass species; P. polystachion, Sorghum arundinaceum (Desv.) Stapf and Panicum maximum Jacq. were tested. Panicum maximum was the most efficient species for suppressing S. calamistis and M. nigrivenella infestations and enhancing egg and larval parasitism. In the Benin trials, with the exception of M. nigrivenella damage to cobs, the grass species tested had no beneficial effect on yield because pest densities were too low and also rodent damage to maize was enhanced with grasses in the vicinity of the crop. By contrast, stand losses due to Fusarium verticillioides Sacc. (Nirenberg), were significantly reduced by border rows of grasses.     

豚草条纹叶的生态学特性

在一定空间(7238厘米~3)的养虫器内,豚草条纹叶(虫甲)成虫的生殖力随密度的增加而下降。单对饲养的生殖力最高,平均产卵386.7粒;当密度为18和25头时,产卵仅157.6和50.4粒。幼虫期以及蛹期的死亡率,在不同空间中均随密度的增加而增加,随空间的增大,各密度下的死亡率相应减少。食料质量是影响幼虫存活的重要因素之一,用豚草上、中、下部叶片饲养幼虫,其死亡率分别为10％、70.3％和97.6％。幼虫期累计食叶量可达90.58毫克鲜重,随着日龄增加,近似消化力逐渐下降,摄入物质转换为体物质的效率和消化食物转换为体物质的效率随日龄的增加而增加。成熟成虫的取食量基本恒定,平均每48小时食叶28.01毫克鲜重,其近似消化力为64.2％。刚羽化出土的成虫,达到成熟进入生殖生长所需的食叶量约为213.22毫克鲜重。     

Bt-maize as a potential trap crop for management of Eldana saccharina Walker (Lep., Pyralidae) in sugarcane

Abstract:  Notwithstanding the introduction of several pest management tactics, the stalk borer Eldana saccharina Walker (Lep., Pyralidae) remains the most serious pest in South African sugarcane. A novel tactic for managing this pest in sugarcane would be the use of a dead-end trap crop that attracts moths for oviposition and curtails subsequent larval development, thereby reducing pest population size. Glasshouse bioassays, in which moths chose to oviposit on maize producing Bacillus thuringiensis Cry1Ab toxin ( Bt -maize), non- Bt -maize or sugarcane of two cultivars (borer-resistant and -susceptible), showed that E. saccharina laid significantly more eggs and egg batches per dry leaf and unit mass of dry leaf on maize ( Bt or non- Bt ) than on either of the cane cultivars. When moths had a choice of ovipositing on 2-, 3-, 4- or 5-month-old maize ( Bt and non- Bt ), dry leaf number and mass of dry leaf material was significantly correlated with number of eggs and egg batches, indicating that older plants, which carried larger amounts of dry leaf matter, were more attractive for oviposition. Finally, glasshouse assays in which hatching larvae fed on 2.5-, 3.5- and 4.5-month-old Bt and non- Bt -maize plants, showed that the Cry1Ab toxin was effective in killing E. saccharina larvae in all Bt -maize plant growth stages, confirming that Bt -maize fulfilled the third requirement (curtailing larval development) of a dead-end trap crop for this pest. We argue that Bt -maize warrants further testing in the field as a trap crop, both alone and as a component of a 'push–pull' or habitat management system for E. saccharina in sugarcane.     

Effects of cultivar on oviposition preference, larval feeding and development time of diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), on some Brassica oleracea vegetables in Victoria

Abstract We studied oviposition preference of Plutella xylostella for four cultivars of cabbage, broccoli and cauliflower in the field. There were no differences in the number of eggs found on the various cultivars of broccoli or cauliflower. Significantly more eggs were laid on cultivar Savoy King than any of the other cabbage cultivars tested. We then compared the development time and feeding damage of larvae reared on Savoy King and Green Coronet cabbages. Larvae developed more rapidly and fed more and for longer on Green Coronet than Savoy King. Thus, while Savoy King is more attractive to oviposition in the field, net impacts on the crop may be lessened to some degree through lower feeding proficiency of the larvae on that cultivar.     

Oviposition preference of Anthocoris nemoralis and A. nemorum (Heteroptera: Anthocoridae) on pear leaves affected by leaf damage, honeydew and prey

Anthocorids are important predators of insect pests in pome fruit. Their choice of oviposition site determines the later distribution of nymphs. In two-choice experiments it was tested whether A. nemorum and A. nemoralis would show oviposition preference with regard to simulated insect damage, mimicked by piercing leaves with a fine pin, and whether the oviposition preference of A. nemoralis was affected by the presence of honeydew or eggs of their prey C. pyri. Leaves with simulated damage were preferred by A. nemoralis, but this was not the case for A. nemorum. Honeydew-treated leaves attracted more oviposition than honeydew-free leaves. On honeydew-treated leaves significantly more eggs were laid on the surface where honeydew had been applied, rather than the opposite. When C. pyri eggs were placed along the abaxial midvein, prey infestation attracted more oviposition. On the infested leaf more eggs were laid near the prey along the abaxial midvein than along the adaxial midvein. In contrast, when prey was placed along the adaxial midvein, no overall preference was found for prey-infested leaves, but on infested leaves, more eggs were laid near the prey along the adaxial midvein than along the abaxial midvein. Results showed that prey cues and presence of prey guide predator oviposition, even within the single leaf. The perspectives for biological control in orchards are discussed.     

草地螟对寄主植物的选择性及其化学生态机制

田间自然条件下,草地螟成虫产卵对不同植物具有明显的选择性,其中灰菜上落卵量最多,占调查总卵量的50%以上;甜菜、大豆上次之,玉米和马铃薯上最少。在室内条件下,草地螟成虫产卵对灰菜、大豆、玉米和马铃薯的选择性与田间调查结果完全吻合。而且,草地螟幼虫的嗜食性与成虫产卵对寄主的选择性是一致的。吸附、收集上述植物的挥发物后进行GC-MS测定,并利用风洞进行了生测。其中灰菜和大豆的主要挥发物成分为反-2-己烯醛、青叶醇、青叶酯、1-十八烯等;玉米和马铃薯的挥发物性成分包括青叶酯、芳樟醇、香叶醇、紫罗酮、1-十八烯。生测结果表明,灰菜的挥发物对草地螟雌蛾引诱力最大,选择系数为78%;大豆苗挥发物对其也有较高的诱虫活性;但玉米和马铃薯几乎无引诱作用。自然生长的4种植物的诱虫结果与其挥发物的诱虫结果相似。这些生测结果与成虫和幼虫选择寄主的一致性反映了草地螟选择寄主行为的化学机制。     

幼虫密度对桑螟生长发育和繁殖的影响

【目的】本研究旨在了解桑螟Diaphania pyloalis幼虫不同饲养密度对其生长发育和繁殖的影响。【方法】本研究测定了室内同一条件下5个幼虫密度(130, 650, 1 300, 1 950和2 600头/m²)下桑螟生长发育和繁殖指标,包括发育历期、幼虫存活率、化蛹率、成虫羽化率、蛹重、产卵期、单雌产卵量等。【结果】幼虫密度对桑螟的生长发育和繁殖均产生不同程度影响,幼虫密度偏低或偏高都不利于桑螟生长发育和繁殖。其中以1 300和1 950头/m² 2种幼虫密度下的桑螟幼虫生长发育和成虫繁殖状态均最佳且两密度下各项指标无明显差异,1 300头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.32, 6.33和5.31 d; 1 950头/m²密度下,桑螟的幼虫历期、蛹历期和成虫历期分别为11.50, 6.00和5.47 d。1 300头/m²幼虫密度下,桑螟化蛹率、成虫羽化率和幼虫存活率分别为86.67%, 100%和86.67%, 1 950头/m^2<...     

甘蔗、玉米气味对亚洲玉米螟成虫产卵和幼虫取食的影响

【目的】农作物间套作对害虫的影响很大程度上取决于害虫的行为反应,通过研究玉米/甘蔗套作系统中植物气味对亚洲玉米螟Ostrinia furnacalis(Guenee)行为的影响,将为利用化学生态手段防治套作田中的害虫提供依据。【方法】通过昆虫触角电位实验、成虫产卵和幼虫取食实验,测定了甘蔗、玉米植株及二氯甲烷漂洗物对亚洲玉米螟成虫产卵、幼虫取食的影响。【结果】亚洲玉米螟成虫在甘蔗植株上的落卵量(卵粒数、卵块数)与玉米植株差异不显著,取食甘蔗植株的幼虫数量显著低于玉米植株。亚洲玉米螟对甘蔗、玉米叶片漂洗物均可产生EAG反应,且在同一浓度下的反应值之间无显著差异。成虫产卵量(卵粒数、卵块数)在0.1 gE/mL浓度的甘蔗和玉米漂洗物间差异不显著;幼虫对经甘蔗叶片漂洗物处理过的饲料的相对取食率均低于65.00%,显著低于玉米漂洗物处理的饲料。【结论】甘蔗和玉米气味对亚洲玉米螟产卵的影响没有差异,但甘蔗气味会导致初孵幼虫表现出很强的逃逸行为。     

Diamondback moth egg susceptibility to rainfall: effects of host plant and oviposition behavior

Oviposition patterns of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), differ between common cabbage (Brassica oleracea L. var. capitata) and Chinese cabbage (Brassica rapa L. var. pekinensis) (Brassicaceae) host plants. This study shows that the moth prefers to oviposit on adaxial rather than abaxial leaf surfaces and petioles of both host plants. More eggs were laid in leaf veins than on leaf laminas of both host plants, especially in Chinese cabbage, where 94.6% of eggs were laid in veins. On Chinese cabbage, very few eggs were laid in clusters (≥2 eggs), whereas on common cabbage approximately 30% of eggs were laid in groups of 2 or more eggs. Removal of wax from common cabbage leaves dramatically increased the number of eggs laid singly on the leaf lamina of treated plants, suggesting that leaf waxes affect how eggs are distributed by ovipositing DBM. Eggs were most susceptible to removal by rainfall from the plant surface immediately (<1 h) after oviposition and when close to hatching (>72h old) whereas they were least susceptible 24 h after oviposition. Eggs laid on common cabbage plants were more susceptible to simulated rainfall than eggs laid on Chinese cabbage plants. On common cabbage plants, egg susceptibility to rainfall on different plant parts ranked adaxial leaf surfaces>petioles = abaxial leaf surfaces>stem, but there was no difference in egg susceptibility to rainfall on the various plant parts of Chinese cabbage. Furthermore, on common cabbage plants, eggs laid on both adaxial and abaxial leaf surfaces were afforded significant protection from the effects of rainfall by leaves higher in the plant canopy. On common cabbage plants, oviposition patterns reduce the potential impact of rainfall on eggs, possibly reducing the effect of this important abiotic mortality factor in the field.     

Volatiles induced by the larvae of the Asian corn borer (Ostrinia furnacalis) in maize plants affect behavior of conspecific larvae and female adults

Abstract  Effects of maize ( Zea mays L.) volatiles induced by larvae of the Asian corn borer, Ostrinia furnacalis (Guenée), on the orientation behaviors of Asian corn borer larvae and oviposition of the females were investigated. Nineteen volatile chemicals, with terpenes being the major components, were identified from maize plants attacked by third instar Asian corn borer larvae. Coupled gas chromatographic-electroantennographic detection (GC-EAD) analyses revealed some electroantennographic differences between female and male Asian corn borer antennae in response to larvae-induced maize volatiles; female responded to ( E )-2-hexenal, nonanal, ( Z )-3-hexen-1-ol and three unknown compounds while the male only responded to ( E )-2-hexenal, nonanal and one unknown compound. In laboratory orientation bioassays, Asian corn borer neonate larvae were attracted to extracts collected from Asian corn borer-damaged plants as well as to synthetic farnesene, but were repelled by ( Z )-3-hexen-1-ol. In laboratory oviposition bioassays, gravid females laid fewer eggs on plants damaged by larvae than on mechanically damaged plants or undamaged plants. Adult Asian corn borer females deposited fewer eggs on wax paper treated with ( E )-2-hexenal or ( Z )-3-hexen-1-ol than on wax paper treated with hexane (control). The results suggest that Asian corn borer can affect the behaviors of conspecific larvae and adults by changing host plant volatiles.     

Influence of Bacillus thuringiensis var. israelensis on oviposition of Aedes albopictus (Skuse).

The effect of Bacillus thuringiensis var israelensis (B.t.i.) on the oviposition behavior of Aedes albopictus was evaluated in the field and laboratory in Clemson, SC, U.S.A. In the field, water taken from containers in which mosquito larvae were reared (conditioned water) was placed in 16 containers. Eight containers received 50 jld of B.t.i., and eight with water only were kept as controls. In the laboratory, field-collected females of Ae. albopictus were placed in rearing chambers and provided two containers for oviposition, one with 50 microl of B.t.i and one a control with water only. Eight cage experiments were conducted, five using filtered tap water and three with conditioned water. In the field over the 13 trials, more eggs were laid in the containers with B.t.i. although no significant difference was found in the number of eggs between the treatment and controls over 72 h. In the laboratory, more eggs were laid in the containers with B.t.i. versus the controls. The containers had filtered tap water and B.t.i. had significantly more eggs laid in them compared to the controls.     

Action of mephosfolan on anthocorid predators of Phorodon humuli

In glasshouse and field studies, soil drenches of the systemic insecticide mephosfolan were applied to hop plants to control the aphid Phorodon humuli, and to study the toxicity to anthocorid predators. The mortality of Anthocoris nemorum and A. nemoralis eggs in the leaf tissues increased with the dosage of mephosfolan while A. confusus eggs, which were laid in the petioles and veins, appeared to be unaffected at the dosages used, up to 2 g a.i./plant. Mortality of A. nemorum eggs, which were laid mainly in the leaf margins, was higher than in A. nemoralis eggs, which were laid mainly in the interveinal areas. For both species mortality was highest for the eggs laid in the leaf margins, and susceptibilities appeared similar. It is suggested that mephosfolan becomes unevenly distributed within the leaves, being most concentrated in the leaf margins and least concentrated in the veins and petioles. No species showed any preference when offered mephosfolan-treated and untreated leaves for oviposition, and the oviposition rates were unaffected by various mephosfolan dosages. Oviposition rates, larval mortality and duration of larval development were unaffected when specimens of each species were reared from eclosion to maturity on a diet of either mephosfolan-killed or heat-killed P. humuli.     

Imperfect oviposition decisions by the pitcher plant mosquito (Wyeomyia smithii)

Summary Wyeomyia smithii mosquitoes distribute their eggs across available oviposition sites (water-holding pitcher plant leaves) of varying quality. I experimentally examined responses to three components of site quality: conspecific larval density, larval density of the pitcher plant midge,Metriocnemus knabi, and pitcher size. Responses to larval treatments were complex and apparently suboptimal. Although mosquito larval performance is better in leaves with fewer conspecific and more midge larvae, females did not lay more eggs in such pitchers. Instead, more eggs were laid in experimental pitchers containing either midge or mosquito larvae, but fewer eggs in pitchers with neither or both. More eggs were laid in larger pitchers, which tend to accumulate more resources and dry out less often. Therefore, although the oviposition decisions made were suboptimal, they were better than random.     

Oviposition aggregation pheromone in the Simulium damnosum complex

Abstract. Communal oviposition by the Simulium damnosum complex of Afrotropical blackflies (Diptera: Simuliidae) was investigated under controlled laboratory conditions, using wild-caught flies in Sierra Leone. Volatile compounds emitted by Simulium eggs were trapped using a closed collection system, and their attractiveness to gravid flies was tested in a two-choice behavioural bioassay. Significantly more female blackflies oviposited on substrates baited with freshly laid eggs (100% chose the baited substrate), or with the volatiles collected from freshly laid eggs (85% chose the baited substrate), in preference to the relevant control substrates. Substrates baited with volatiles from 12-h-old eggs were not significantly more attractive than controls (only 31% chose the baited substrates; P = 0.33). Gas chromatographic analysis of the egg volatiles consistently showed two peaks emanating from fresh eggs, but significantly lower amounts from 12-h-old eggs ( P <0.05). A novel system for collecting the volatiles from this and other blackfly species, as they laid eggs on a substrate in flowing water, is described. Volatiles collected using this method showed identical gas chromatographic profiles to those of fresh eggs alone, indicating that the flies themselves produced no other volatile chemical signals during oviposition. Evidently communal oviposition by S. damnosum s.l . was mediated by a pheromone emanating from fresh eggs. The role of pheromone-mediated egg aggregation in blackfly ecology is discussed, and its possible manipulation is considered.     

草地贪夜蛾对5种寄主植物和6种杂草的取食选择性和适应性

为明确草地贪夜蛾Spodoptera frugiperda J. E. Smith对不同寄主植物和主要杂草的取食选择及适应性,以玉米Zea mays、甘蔗Saccharum officinarum、花生Arachis hypogaea、大豆Glycine max、香蕉Musa nana、稗草Echinochloa crusgalli、马唐Digitaria sanguinalis、牛筋草Eleusine indica、莎草Cyperus rotundus、马齿苋Portulaca oleracea、鹅肠草Malachium aquaticum作为寄主,采用叶碟法测定草地贪夜蛾各龄幼虫对5种寄主植物和6种杂草的取食偏好,并测定了不同虫态的发育历期、单头蛹重、化蛹率以及单雌产卵量等。结果表明,草地贪夜蛾在5种寄主植物和6种杂草上均可完成世代发育。寄主作物中,香蕉处理的草地贪夜蛾成虫前期最长,为29.66 d;甘蔗处理下草地贪夜蛾蛹重和化蛹率分别为250.44 mg和71.67%,显著低于玉米和花生处理的蛹重和化蛹率;草地贪夜蛾取食花生后单雌产卵量最高,为768.93粒,与玉米上产卵量差异不显著,香蕉上最低,为498.76粒;1~2龄幼虫对玉米和香蕉的取食选择率有显著差异,3~6龄幼虫对玉米取食选择率显著高于其他寄主植物。6种杂草中取食莎草的成虫前期最长30.21 d,且单雌产卵量最低526.33粒;取食鹅肠草蛹重最低188.00 mg;取食马齿苋化蛹率最低为72.37%;草地贪夜蛾取食马唐后其蛹重、化蛹率、单雌产卵量最高,与取食其它5种杂草有显著性差异;2~4龄幼虫更偏向取食马唐,与其它5种差异显著。研究结果表明：寄主植物种类对草地贪夜蛾的生长发育有显著影响,其中草地贪夜蛾对玉米和马唐具有较高的取食偏好。     

Simultaneous monitoring of flight and oviposition of individual velvetbean caterpillar moths

ABSTRACT. A 'pivot' flight actograph was combined with a rolling oviposition surface to characterize the flight and oviposition behaviour of velvetbean caterpillar moths, Anticarsia gemmatalis Hubner. Tethered, caged control females laid significantly more eggs that those flown on the actograph. Mated females laid more eggs than unmated ones. However, mating did not affect longevity nor fight frequency and duration. Laboratory-reared and wild-type females also did not differ signficantly in longevity and flight. Both laboratory and wild mated females laid most of their eggs during the first 7 days whereas unmated ones delayed their oviposition. None of the female types produced a definite hourly, daily or lifetime pattern in flight frequency or duration. Of the 7672 recorded flights, about 3% were greater than 0.5 h. 'Long' flights (>0.5h) were made by some females before oviposition, as in colonization migration, but most interspersed flight with oviposition, as in extended search migration.     

Dynamics of oviposition in Danaus plexippus (Insecta: Lepidoptera) on milkweed, Asclepias spp

Where a butterfly chooses to lay an egg will influence the subsequent survival of her offspring. In this paper we report on the effect of a number of variables which influence the choice of oviposition site in Danaus plexippus L. Experiments were conducted under both flight cage and field conditions. The field observations consisted of recording the within and between plant egg dispersions across different patch sizes. Laboratory experiments looked at egg laying preferences as affected by plant species, age and condition. Butterflies were selective in their choice of oviposition site. Eggs were laid singly on the underside of medium sized leaves towards the top of a plant. More eggs were laid per plant on single isolated plants than on plants within a patch. The number of eggs per plant increases with plant height but decreases with plant age. Females preferred young plants or plants with fresh regrowth of leaves. These characteristics could override species preferences which were, in decreasing order, Asclepias curassavica. A. fruticosa and A. physocarpa. Species preferences varied between butterflies and with female age. Neither the presence of eggs nor larvae on a plant deterred oviposition. These results are compared with previous observations of egg laying in this species.     

Oviposition Behaviour and Reproductive Performance of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) Reared in Artificial Diet

Biotypes of Trichogramma australicum were reared on artificial diet "A", Helicoverpa armigera (Hübner) (natural host) eggs and Sitotroga cerealella (Olivier) (factitious host) eggs. We evaluated the quality of these biotypes by comparing their oviposition behaviour and reproductive performance on H. armigera eggs. Female T. australicum reared in vitro accepted H. armigera eggs for oviposition and displayed similar behavioural components of oviposition to females reared on natural hosts. However, handling time during oviposition in H. armigera eggs by females from in vitro rearing was significantly longer than handling time of females reared on the natural host because the females needed a significantly longer time for host feeding. In vitro reared females produced significantly more progeny and parasitised more H. armigera eggs than the females reared on S. cerealella. Improvements to the artificial diet for T. australicum may reduce handling time of the in vitro reared females and increase the female population. These improvements may include changes in nutrient content and size of the artificial eggs.     

日本刀角瓢虫对不同叶毛密度茄子品种的产卵选择性

【目的】产卵是昆虫发育过程中繁衍后代、维持种群数量的重要环节。在前期研究发现日本刀角瓢虫Serangium japonicum喜欢在茄子Solanum melongena叶片上产卵的前提下,本研究旨在深入探究日本刀角瓢虫对不同叶毛密度茄子品种的产卵选择性,以期进一步明确植物叶毛介导的日本刀角瓢虫产卵选择机制。【方法】观察日本刀角瓢虫雌成虫在4个茄子品种(黑到底、黑妞、日友长直壮、络星)叶碟和植株上的产卵选择性,测定不同茄子品种上日本刀角瓢虫后代的生长发育及成虫的繁殖力、捕食能力和对叶片的附着力,观察4个茄子品种叶片背面超微结构,测定日本刀角瓢虫雌成虫对茄子叶片的气味选择,测量茄子叶片上烟粉虱Bemisia tabaci卵粒的长度和宽度,测定日本刀角瓢虫卵被其雌成虫的同类捕食风险。【结果】日本刀角瓢虫偏好在黑到底上产卵,后代个体在黑到底品种上总发育历期(15.41±0.21 d)最短,亲代单雌产卵量(877.44±15.27粒/头)最高。但是,日本刀角瓢虫的产卵量占比与子代生长表现(发育历期、存活率和成虫体重)和成虫生存表现(繁殖力和捕食能力)均无显著相关性,而与叶片背面叶毛密度和长度存在显著正相关性;日本刀角瓢虫在茄子叶碟上的产卵量占比与日本刀角瓢虫雌成虫附着力存在显著正相关性。日本刀角瓢虫雌成虫附着力与叶毛密度显著正相关,而与亲代生长表现无显著相关关系。茄子叶片气味、猎物质量以及被同类捕食风险均不显著影响日本刀角瓢虫的产卵选择。【结论】茄子叶片背面叶毛密度及叶毛介导的日本刀角瓢虫附着力在日本刀角瓢虫对茄子叶片的产卵选择性中起重要作用。     

Long-term seasonal fluctuations of lepidopteran cereal stemborers and their natural enemies on maize and wild host plants in southern Benin

Abstract  The seasonal fluctuation of lepidopteran cereal stemborers on maize and wild host plants (i.e., grasses and a few sedges) was investigated in southern Benin from 1988 to 1998 by time series analysis and repeated-measures analysis of variance (ANOVA). In addition, a walk-in light trap was used to study the flight behavior of adult moths. On both cereals and grasses, the noctuid Sesamia calamistis was the predominant species, followed by the pyralid Eldana saccharina . The noctuid Busseola fusca was rare on both maize and wild host plants. In general, pest populations increased during the course of the year to reach peak densities during the second short rainy season, and then crashed to close to zero during the dry season. On wild host plants, egg masses and other immature stages were collected throughout the year but they were higher on wild grasses than maize during the off-season. Thus wild host plants can be considered as refuge for both borers and natural enemies during the off-season, when maize is not available. However, only four out of the eleven wild host species played a discernable role. S. calamistis egg densities appeared to be influenced by density-dependent factors, suggesting an effect of natural enemies. Temperature and rainfall had a negative effect on egg abundance. Larval parasitism by a Kenyan strain of the braconid Cotesia sesamiae , which was released in southern Benin in the early 1990s, and by the tachinid Sturmiopsis parasitica varied between seasons and years but there were no discernable patterns. For both parasitoids and borer host species, parasitism was positively correlated with trap catches of adult moths. The recovery of C. sesamiae during a 2-year period suggests that the parasitoid has established its population in southern Benin.