Attraction of the specialist parasitoid Cotesia rubecula to Arabidopsis thaliana infested by host or non-host herbivore species

In this study we investigated whether in a two‐choice set‐up the parasitoid Cotesia rubecula (Marshall) (Hymenoptera, Braconidae) distinguishes between volatiles emitted by Arabidopsis thaliana (L.) Heynh. (Brassicaceae) infested with its host, Pieris rapae (L.) (Lepidoptera: Pieridae) and Arabidopsis infested with non‐host herbivores. Four non‐host herbivore species were tested: the caterpillars Plutella xylostella (L.) (Lepidoptera: Plutellidae) and Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), both chewing insects, the spider mite Tetranychus urticae (Koch) (Acari: Tetranychidae), which punctures parenchymal cells, and the aphid Myzus persicae (Sulzer) (Hemiptera: Aphidoidea), which is a phloem‐feeder. Compared with undamaged plants, C. rubecula females were more attracted to Arabidopsis plants infested by P. rapae, P. xylostella, S. exigua, or T. urticae, but not to plants infested by M. persicae. The parasitoids preferred host‐infested plants to spider mite‐ or aphid‐infested plants, but not to plants infested with non‐host caterpillars (P. xylostella or S. exigua). The data show that when Arabidopsis plants are infested with a leaf tissue‐damaging herbivore they emit a volatile blend that attracts C. rubecula females and the wasps only discriminate between a host and non‐host herbivore when the type of damage is different (chewing vs. piercing). When Arabidopsis is infested with a herbivore that hardly damages leaf tissue, C. rubecula females are not attracted. These results may be explained by differences in the amount of damage and in the relative importance of different signal‐transduction pathways induced by different types of herbivores.     

Seasonal variations in intermediatory metabolism of the bivalves Cerastoderma edule and Scrobicularia plana during exposure to air

Seasonal changes in the operation of the succinate pathway by different tissues of two species of bivalve molluscs (Cerastoderma edule (L.) and Scrobicularia plana) were investigated. No significant changes were observed in tissues of C. edule. However, there were significant seasonal changes in the operation of the pathway by tissues of S. plana. The succinate pathway operates in S. plana at a higher rate in summer and autumn than in witer. The results are discussed in relation to food availability, temperature and the reproductive cycle.     

The role of herbivore‐ and plant‐related experiences in intraspecific host preference of a relatively specialized parasitoid

Parasitoids use odor cues from infested plants and herbivore hosts to locate their hosts. Specialist parasitoids of generalist herbivores are predicted to rely more on herbivorederived cues than plant-derived cues. Microplitis croceipes (Cresson)(Hymenoptera: Braconidae) is a relatively specialized larval endoparasitoid of Heliothis virescens (F.)(Lepidoptera: Noctuidae), which is a generalist herbivore on several crops including cotton and soybean. Using M. croceipes/H. virescens as a model system, we tested the following predictions about specialist parasitoids of generalist herbivores:(i) naive parasitoids will show innate responses to herbivore-emitted kairomones, regardless of host plant identity and (ii) herbivore-related experience will have a greater influence on intraspecific oviposition preference than plant-related experience. Inexperienced (naive) female M. croceipes did not discriminate between cotton-fed and soybean-fed H. virescens in oviposition choice tests, supporting our first prediction. Oviposition experience alone with either host group influenced subsequent oviposition preference while experience with infested plants alone did not elicit preference in M. croceipes, supporting our second prediction. Furthermore, associative learning of oviposition with host-damaged plants facilitated host location. I terestingly, naive parasitoids attacked more soybeathan cotton-fed host larvae in two-choice tests when a background of host-infested cotton odor was supplied, and vice versa. This suggests that plant volatiles may have created an olfactory contrast effect. We discussed ecological significance of the results and concluded that both plant- and herbivore-related experiences play important role in parasitoid host foraging.     

Identification of risk areas for Orobanche cumana and Phelipanche aegyptiaca in China,based on the major host plant and CMIP6 climate scenarios

Parasitic broomrape of the genus Orobanche poses a formidable threat to producing many crops in Europe, Africa, and Asia. Orobanche cumana and Phelipanche aegyptiaca are two of China''s most destructive root parasitic plants, causing extreme sunflower, tomato, melon, and tobacco damage. However, the potentially suitable areas of O. cumana and P. aegyptiaca in China have not been predicted, and little is known about the important environmental factors that affect their extension. Due to their invasiveness and economic importance, studying how climate change and host plants may affect broomrapes’ distribution is necessary. In the study, we first predicted the potentially suitable areas of the invasive weeds (O. cumana and P. aegyptiaca) and their susceptible host plants (Helianthus annuus and Solanum lycopersicon) using MaxEnt. Then, the risk zones and distribution shifts of two broomrapes under different climate conditions were identified by incorporating the distribution of their susceptible host plants. The results highlighted that the potential middle‐ and high‐risk zones for O. cumana and P. aegyptiaca amounted to 197.88 × 10⁴ km² and 12.90 × 10⁴ km², respectively. Notably, Xinjiang and Inner Mongolia were the highest‐risk areas within the distribution and establishment of O. cumana and P. aegyptiaca. Elevation and topsoil pH were the decisive factors for shaping O. cumana distribution; precipitation seasonality and annual precipitation were the dominant bioclimatic variables limiting the spread of P. aegyptiaca. The potentially suitable areas and risk zones of O. cumana would decrease significantly, and those of P. aegyptiaca would fluctuate slightly under future climate change scenarios. Overall, our study suggested that the two broomrapes’ risk zones will significantly northward to higher latitudes. The results will provide suggestions for preventing O. cumana and P. aegyptiaca.     

Host‐parasite relationship: occurrence and effect of Ceratothoa parallela (Otto, 1828) on Boops boops (L., 1758) in the Southern Tyrrhenian Sea

The host‐parasite relationship between bogue (Boops boops) and Cerathotoa parallela (Isopoda: Cymothoidae) was studied in the Southern Tyrrhenian Sea (overall prevalence of isopods in the area, age‐dependent and sex‐dependent prevalence). Yearly prevalence ranged from 1.0% in March to 10.7% in October, with a positive correlation between prevalence and mean sea surface temperatures (SST), highest values being related to the period of increasing SST. The first four age‐classes were parasitized, with prevalence decreasing according to the age of the host. The relationship between total length (TL) and total weight (TW) was examined in infested and non‐infested specimens of the same age whereby slight differences were detected, i.e. at a given length non‐infested specimens weighed more than infested fishes. The parasite occurred throughout the study area with wide fluctuations in prevalence, from 0 to 36.4%, the values being higher in the eastern part of the study area. C. parallela parasitize the bogue Boops boops in a manner that does not constitute a serious threat to the life of the host.     

Oxydromus Grube, 1855 reinstated over Ophiodromus Sars, 1862 (Polychaeta,Hesionidae)

The hesionid polychaete genera Oxydromus Grube, 1855 and Ophiodromus Sars, 1862 have been regarded as synonyms with the former considered as invalid since it was thought to be a junior homonym of Oxydromus Schlegel, 1854. However, Schlegel’s name is an incorrect subsequent spelling for Ocydromus Wagler, 1830 (Aves, Gruiformes, Rallidae) and is not an available name. Consequently, Oxydromus Grube, 1855 must be reinstated for this hesionid polychaete genus. A check-list of valid species of Oxydromus including 30 new combinations is provided.     

A review of the Iberian Sphingonotini with description of two novel species (Orthoptera: Acrididae: Oedipodinae)

The genus Sphingonotus Fieber, 1853 is one of the most species‐rich grasshopper genera in the world. We studied the morphology of c. 1000 individuals from the Iberian Peninsula to review the taxonomy of the genus and its relatives. Moreover, we inferred a molecular phylogeny of the Iberian Sphingonotini based on two mitochondrial genes. The Iberian and north‐west African Sphingonotini comprise two recent radiations, within which the genetic relationships are not fully resolved. A multivariate morphometric analysis showed that S. azurescens (Rambur, 1838) and S. morini (Defaut, 2005) can be clearly discriminated, supporting their species status. Based upon the combined data, the genus Granada Koçak & Kemal, 2008 is synonymized with Sphingonotus Fieber, 1853 and its type species re‐assigned to Sphingonotus imitans Brunner von Wattenwyl, 1882 comb. rev . The data also supported species rank for Sphingonotus lusitanicus Ebner, 1941 comb. rev. Oedipoda callosa Fieber, 1853 is considered as nomen dubium. Two novel species are described: Sphingonotus ( Neosphingonotus ) almeriense Llucià‐Pomares sp. nov . and Sphingonotus (Neosphingonotus) nodulosus Llucia‐Pomares sp. nov. from the southern part of the Iberian Peninsula. The new species are compared with other Iberian Sphingonotini and a key to the species is provided. © 2013 The Linnean Society of London     

Effects of quantitative and qualitative differences in volatiles from host‐ and non‐host‐infested maize on the attraction of the larval parasitoid Cotesia kariyai

Cotesia kariyai Watanabe (Hymenoptera: Braconidae) is a specialist larval parasitoid of Mythimna separata Walker (Lepidoptera: Noctuidae). Cotesia kariyai wasps use herbivore‐induced plant volatiles (HIPVs) to locate hosts. However, complex natural habitats are full of volatiles released by both herbivorous host‐ and non‐host‐infested plants at various levels of intensity. Therefore, the presence of non‐hosts may affect parasitoid decisions while foraging. Here, the host‐finding efficiency of naive C. kariyai from HIPVs influenced by host‐ and non‐host‐infested maize [Zea mays L. (Poaceae)] plants was investigated with a four‐arm olfactometer. Ostrinia furnacalis Guenée (Lepidoptera: Crambidae) was selected as a non‐host species. One unit (1 U) of host‐ or non‐host‐infested plant was prepared by infesting a potted plant with five host or seven non‐host larvae. In two‐choice bioassays, host‐infested plants fed upon by different numbers of larvae, and various units of host‐ and non‐host‐infested plants (infestation units; 1 U, 2 U, and 3 U) were arranged to examine the effects of differences in volatile quantity and quality on the olfactory responses of C. kariyai with the assumption that volatile quantity and quality changes with differences in numbers of insects and plants. Cotesia kariyai was found to perceive quantitative differences in volatiles from host‐infested plants, preferring larger quantities of volatiles from larger numbers of larvae or plants. Also, the parasitoids discriminated between healthy plants, host‐infested plants, and non‐host‐infested plants by recognising volatiles released from those plants. Cotesia kariyai showed a reduced preference for host‐induced volatiles, when larger numbers of non‐host‐infested plants were present. Therefore, quantitative and qualitative differences in volatiles from host‐ and non‐host‐infested plants appear to affect the decision of C. kariyai during host‐habitat searching in multiple tritrophic systems.     

Ultrastuctural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca,Bivalvia)

The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome-like junctions, elongated spermatids are held at the acrosomal region by support cell finger-like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.     

Histories of host shifts and cospeciation among free‐living parasitoids of Rhagoletis flies

Host shifts by specialist insects can lead to reproductive isolation between insect populations that use different hosts, promoting diversification. When both a phytophagous insect and its ancestrally associated parasitoid shift to the same novel host plant, they may cospeciate. However, because adult parasitoids are free living, they can also colonize novel host insects and diversify independent of their ancestral host insect. Although shifts of parasitoids to new insect hosts have been documented in ecological time, the long‐term importance of such shifts to parasitoid diversity has not been evaluated. We used a genus of flies with a history of speciation via host shifting (Rhagoletis [Diptera: Tephritidae]) and three associated hymenopteran parasitoid genera (Diachasma, Coptera and Utetes) to examine cophylogenetic relationships between parasitoids and their host insects. We inferred phylogenies of Rhagoletis, Diachasma, Coptera and Utetes and used distance‐based cophylogenetic methods (ParaFit and PACo) to assess congruence between fly and parasitoid trees. We used an event‐based method with a free‐living parasitoid cost model to reconstruct cophylogenetic histories of each parasitoid genus and Rhagoletis. We found that the current species diversity and host–parasitoid associations between the Rhagoletis flies and parasitoids are the primary result of ancient cospeciation events. Parasitoid shifts to ancestrally unrelated hosts primarily occur near the branch tips, suggesting that host shifts contribute to recent parasitoid species diversity but that these lineages may not persist over longer time periods. Our analyses also stress the importance of biologically informed cost models when investigating the coevolutionary histories of hosts and free‐living parasitoids.     

Distribution,host plant affiliation,phenology, and phylogeny of walnut‐infesting Rhagoletis flies (Diptera: Tephritidae) in Mexico

Many taxa of Nearctic origin have diversified in the subtropical highlands of Mexico. In particular, flies in the genus Rhagoletis have undergone episodes of isolation and gene flow during Pleistocene glaciations and post‐glacial times that have produced lineage differentiation and reproductive isolation. To reach a better understanding of the phylogeography of the genus Rhagoletis, a host plant survey of the walnut‐infesting Rhagoletis suavis species group was conducted across sixteen states comprising 34 different collecting sites in Mexico over a 9‐year period. Five species of Juglans were found to be infested by three species of walnut‐attacking Rhagoletis flies. Several species of parasitoids were also recovered from collections, but in contrast to their walnut fly hosts, they revealed little evidence for host or geographic subdivision. There was no consistent difference in mean eclosion time between walnut fly species or populations associated with different host walnuts in Mexico, unlike the case for other Rhagoletis species, in which allochronic isolation arising from variation in diapause timing is a major ecological adaptation, reproductively isolating flies. We compare the distribution of R. suavis flies in Mexico with those of other Rhagoletis species attacking hawthorns and cherries, and discuss its implications for population divergence and speciation. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 765–779.     

New insights into the symbiosis between Zanclea (Cnidaria,Hydrozoa) and scleractinians

Hydroids in the genus Zanclea are a recently discovered component of the fauna associated with reef‐building corals. The phylogenetic relationships among these species are not well known. The present work is based on field surveys in the Republic of Maldives, and for the first time, morphological and molecular analyses are integrated to distinguish a new hydroid species and provide new information on the ecology of this symbiosis. This new hydroid, Zanclea gallii sp. n., was associated with the scleractinian Acropora muricata; it was living sympatrically with its congener Zanclea sango, which was observed for the first time at this locality on the new scleractinian host Pavona varians. The relationships between these two hydroids and other available scleractinian‐associated Zanclea were investigated using two molecular markers, nuclear 28S rDNA and mitochondrial 16S rRNA. Zanclea gallii sp. n. and Z. sango were recovered as distinct lineages within a monophyletic group of scleractinian‐associated Zanclea based on both molecular and morphological data. All Zanclea species that were observed living in association with scleractinians belong to the ‘polymorpha group’ and share the morphological characteristic ‘polymorphic colony’. The genus Leptoseris is the 16th host coral identified for Zanclea. Compared with the frequency of the Z. gallii sp. n. association with A. muricata and Z. sango with the scleractinian P. varians, the latter is twice as common; however, the former exhibited higher Zanclea polyps concentrations over the colony surface. Overall, the Zanclea survey indicates that these diminutive hydroids are more commonly associated with coral than previously known.     

Aboveground herbivory affects indirect defences of brassicaceous plants against the root feeder Delia radicum Linnaeus: laboratory and field evidence

1. Belowground herbivory has recently been shown to disrupt the host location behaviour of aboveground parasitoids and thereby impact plants indirect defences. Reverse interactions, on the other hand, have received little attention so far. 2. Lab and field studies were conducted to examine whether the presence of the leaf herbivore Pieris brassicae Linnaeus on brassicaceous plants influences the response of Trybliographa rapae Westwood, a specialist parasitoid of the root feeder Delia radicum Linnaeus. 3. The present results show that the attraction of the parasitoid towards host‐infested plants disappeared when these plants were also infested by P. brassicae. This absence of attraction was observed both when the complete odour blend or only undamaged leaves from damaged plants were offered, emphasising the role of systemically induced volatiles for host location in T. rapae. 4. Furthermore, the field study revealed that parasitism levels dropped from 30% on root‐infested plants to 4% on double‐infested plants. 5. The present study is the first to confirm that reduced attraction to host‐infested plants as a result of simultaneous attack by below‐ and aboveground herbivores translates into lower levels of parasitism in the field.     

Influence of Mycorrhizal Inoculation, Inundation Period, Salinity, and Phosphorus Availability on the Growth of Two Salt Marsh Grasses, Spartina alterniflora Lois. and Spartina cynosuroides (L.) Roth., in Nursery Systems

Restoration of salt marsh ecosystems is an important concern in the eastern United States to mitigate damage caused by industrial development. Little attention has been directed to the mycorrhizal influence on plantings of salt marsh species to stabilize estuarine sediments and establish cover. In our study, seedlings of two salt marsh grasses, Spartina alterniflora and Spartina cynosuroides, were grown in soil with a commercial, mixed species inoculum of arbuscular mycorrhizal fungi. Plants were grown in experimental “ebb and flow” boxes, simulating three levels of tidal inundation, to which two levels of applied phosphorus (P) and two levels of salinity were imposed. After 2.5 months, S. alterniflora was poorly colonized by arbuscular mycorrhizae, developing only fungal hyphae and no arbuscules, but S. cynosuroides became moderately colonized. Mycorrhizal inoculation marginally improved growth and P and nitrogen (N) content of both plant species at low levels of P supply but significantly increased tillering in both plant species. This factor could be beneficial in enhancing ground cover during restoration procedures. Greater P availability increased the mycorrhizal status of S. cynosuroides and improved P nutrition of both plant species, despite a reduction in the root‐to‐shoot ratio. Increasing salinity reduced mycorrhizal colonization of S. alterniflora but not of S. cynosuroides. Growth and nutrient content of S. alterniflora was improved at higher levels of salinity, but only increased nutrient content in S. cynosuroides. Increased duration of tidal inundation decreased plant growth in both species, but tissue P and N concentrations were highest with the longest time of inundation in both species.     

Effects of abiotic factors on the life span of the invasive cordgrass <Emphasis Type="Italic">Spartina densiflora</Emphasis> and the native <Emphasis Type="Italic">Spartina maritima</Emphasis> at low salt marshes

We analyzed variations in the life span of the invasive cordgrass Spartina densiflora at low marshes of SW Iberian Peninsula, and identified the abiotic factors limiting the plant in the absence of competition. With these objectives, clump survivorship, flowering, and growth of S. densiflora were studied in two natural populations at different low marsh elevations during more than three years, and at a transplant experiment in comparison with the native Spartina maritima. The life spans of both cordgrasses changed depending on small variations of a few centimeters in elevation. S. maritima, which tolerates better than S. densiflora the stressful abiotic environment of lower marshes, showed a significant lower distribution limit for its perennial habit, with survivorship longer than three years (from 1997 to 2000), than the neophyte (+1.57 m SHZ vs. +2.00 m SHZ). S. densiflora clumps flowered before dying at mostly all elevations, showing low relative growth rates. In contrast, clumps of S. maritima, with non-viable seeds, only flowered when they were three years old at higher elevations in the low marsh. Our results have applications for salt marshes bioengineering projects and to prevent S. densiflora from invading European marshes since our data improve the knowledge of its colonization mechanisms through salt marsh zonation and so identify those portions of restored and native marshes most susceptible to invasion due to the establishment of perennial populations.     

Abundance,Population Structure and Production of Scrobicularia plana and Abra tenuis (Bivalvia: Scrobicularidae) in a Mediterranean Brackish Lagoon,Lake Ichkeul,Tunisia

Abundance, growth and production of the deposit‐feeding bivalves were studied in the Ichkeul wetland, northern Tunisia, from July 1993 – April 1994. Scrobicularia plana (Da Costa , 1778) occurred at annual mean densities (biomasses) of 299 ± 65 to 400 ± 100 individuals/m² (22.54 ± 3.00 to 34.27 ± 3.96 g ash‐free dry mass (AFDM)/m²) depending on the study area. The annual mean density of Abra tenuis (Montagu , 1803) amounted to 640 ± 74 individuals/m² during the whole study period, in contrast the biomass rose from 2.87 g AFDM/m² in July to 10.29 g AFDM/m² in April. Both species were largely dominated by age class I. Although not very successful, recruitment presented a two‐period pattern: the main period at the beginning of spring, and a secondary one in late summer/autumn. S. plana rarely exceeded 40 mm and lived for only 2 years, while most individuals of A. tenuis lived for only 15–18 months growing to a length of 12 mm. The annual bivalve deposit‐feeder production for the whole lagoon system (90 km²) was 8.24 g AFDM/m² (5.26 g C/m², 0.65 g N/m²). The annual P/ ratio was about 0.4 and therefore in the same order of magnitude as estimates from other brackish coastal waters. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Facilitation in bark beetles: endemic mountain pine beetle gets a helping hand

• 1 Endemic populations of the bark beetle Dendroctonus ponderosae attack weakened lodgepole pine (Pinus contorta var. latifolia) trees that are often previously infested by other bark beetle species, such as Pseudips mexicanus.
• 2 The effect of interactions on D. ponderosae was assessed by examining host selection and productivity of D. ponderosae in trees containing P. mexicanus and trees infested solely by D. ponderosae.
• 3 The findings obtained show that D. ponderosae attacked hosts previously occupied by P. mexicanus at greater densities, and offspring emerged earlier compared with hosts infested by D. ponderosae alone. Additionally, D. ponderosae larvae in P. mexicanus‐infested trees were found to require a significantly lower amount of resource to complete development with no loss in size.
• 4 The presence of P. mexicanus may affect host condition, improving the subcortical environment for endemic D. ponderosae, ultimately aiding in population maintenance at low levels. Hosts in this state should be preferentially attacked by D. ponderosae.

     

Examining the impact of a symbiotic lifestyle on the fecundity of the marine gastropod Crepidula plana

The marine gastropod Crepidula plana has an extensive latitudinal range along the eastern coast of the United States. It is usually found living within gastropod shells occupied by hermit crabs, although individuals can sometimes also be found living on rocks and on the exposed surfaces of shells. Our study sought to determine the extent to which residing inside periwinkle (Littorina littorea) shells occupied by the hermit crab Pagurus longicarpus at a study site in coastal Massachusetts compromises the fecundity of C. plana, through size limitation. The egg masses of symbiotic and free‐living females of C. plana included comparable numbers of egg capsules and embryos per female despite the smaller sizes of the symbionts; symbiotic females compensated for their smaller size by producing significantly more embryos per milligram of female body tissue than their free‐living counterparts. These data raise interesting questions about why—unlike its congener C. fornicata—C. plana has not yet become a successful invasive species.     

Role of volatiles emitted by host and non-host plants in the foraging behaviour of Dentichasmias busseolae, a pupal parasitoid of the spotted stemborer Chilo partellus

The role of volatiles from stemborer host and non‐host plants in the host‐finding process of Dentichasmias busseolae Heinrich (Hymenoptera: Ichneumonidae) a pupal parasitoid of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) was studied. The non‐host plant, molasses grass (Melinis minutiflora Beauv. (Poaceae)), is reported to produce some volatile compounds known to be attractive to some parasitoid species. The studies were conducted to explore the possibility of intercropping stemborer host plants with molasses grass in order to enhance the foraging activity of D. busseolae in such a diversified agro‐ecosystem. Olfactometric bioassays showed that volatiles from the host plants maize, Zea mays L., and sorghum, Sorghum bicolor (L.) (Poaceae), were attractive to the parasitoid. Infested host plants were the most attractive. Volatiles from molasses grass were repellent to the parasitoid. Further tests showed that volatiles from infested and uninfested host plants alone were preferred over those from infested and uninfested host plants combined with the non‐host plant, molasses grass. In dual choice tests, the parasitoid did not discriminate between volatiles from maize infested by either of the two herbivore species, C. partellus or Busseola fusca Fuller (Lepidoptera: Noctuidae). Volatiles from sorghum infested by C. partellus were preferred over those from C. partellus‐infested maize. The study showed that the pupal parasitoid D. busseolae uses plant volatiles during foraging, with those from the plant–herbivore complex being the most attractive. The fact that volatiles from molasses grass were deterrent to the parasitoid suggested that intercropping maize or sorghum with molasses grass was not likely to enhance the foraging behaviour of D. busseolae. Volatiles from the molasses grass may hinder D. busseolae's host location efficiency.