Life history and host range of Sauris nr. purpurotincta,an unsuitable biological control agent for Chinese tallowtree

Foreign surveys in China discovered a defoliating insect species feeding on the leaves of Chinese tallowtree (Triadica sebifera), an invasive weed of the southeastern U.S.A. The life history of this species, Sauris nr. purpurotincta (Lepidoptera: Geometridae), was examined and larval no-choice and adult multiple-choice host range tests were conducted in quarantine to evaluate their suitability for biological control of Chinese tallowtree. The results indicated that the larvae have five instars and require approximately 22 days to complete development to the adult stage. Host range tests indicated that the larvae could not feed and complete development on most species tested. However, 40% of the larvae survived when fed leaves of Hippomane mancinella, a state-listed endangered species in Florida, and all larvae survived when fed Morella cerifera, a common native species of the southeastern U.S.A. Multiple-choice oviposition tests indicated eggs were laid on leaves of both a south Florida native plant Gymnanthes lucida and Chinese tallowtree. Considering this broad host range, this species will not be considered further for biological control of Chinese tallowtree in the U.S.A.     

Preference of Bt‐resistant and susceptible Busseola fusca moths and larvae for Bt and non‐Bt maize

The sustainability of genetically engineered insecticidal Bacillus thuringiensis Berliner (Bt) maize, Zea mays L. (Poaceae), is threatened by the evolution of resistance by target pest species. Several Lepidoptera species have evolved resistance to Cry proteins expressed by Bt maize over the last decade, including the African maize stem borer, Busseola fusca (Fuller) (Lepidoptera: Noctuidae). The insect resistance management (IRM) strategy (i.e., the high‐dose/refuge strategy) deployed to delay resistance evolution is grounded on certain assumptions about the biology and ecology of a pest species, for example, the interactions between the insect pest and crop plants. Should these assumptions be violated, the evolution of resistance within pest populations will be rapid. This study evaluated the assumption that B. fusca adults and larvae select and colonize maize plants at random, and do not show any preference for either Bt or non‐Bt maize. Gravid female B. fusca moths of a resistant and susceptible population were subjected to two‐choice oviposition preference tests using stems of Bt and non‐Bt maize plants. Both the number of egg batches as well as the total number of eggs laid on each stem were recorded. The feeding preference of Bt‐resistant and susceptible neonate B. fusca larvae were evaluated in choice test bioassays with whorl leaf samples of specific maize cultivars. Although no differential oviposition preference was observed for either resistant or susceptible female moths, leaf damage ratings indicated that neonate larvae were able to detect Bt toxins and that they displayed feeding avoidance behaviour on Bt maize leaf samples.     

Observations of parasitoid behaviour in both no‐choice and choice tests are consistent with proposed ecological host range

The solitary larval endoparasitoid Eadya daenerys Ridenbaugh (Hymenoptera: Braconidae) is a proposed biocontrol agent of Paropsis charybdis Stål (Coleoptera: Chrysomelidae, Chrysomelinae), a pest of eucalypts in New Zealand. Eadya daenerys oviposition behaviour was examined in two assay types during host range testing, with the aim of improving ecological host range prediction. No‐choice sequential and two‐choice behavioural observations were undertaken against nine closely related species of New Zealand non‐target beetle larvae, including a native beetle, introduced weed biocontrol agents, and invasive paropsine beetles. No behavioural measure was significantly different between no‐choice and two‐choice tests. In sequential no‐choice assays the order of first presentation (target–non‐target) had no significant effect on the median number of attacks or the attack rate while on the plant. Beetle species was the most important factor. Parasitoids expressed significantly lower on‐plant attack rates against non‐targets compared to target P. charybdis larvae. The median number of attacks was always higher towards target larvae than towards non‐target larvae, except for the phylogenetically closest related non‐target Trachymela sloanei (Blackburn) (Coleoptera: Chrysomelidae, Chrysomelinae). Most non‐target larvae were disregarded upon contact, which suggests that the infrequent attack behaviour observed by two individual E. daenerys against Allocharis nr. tarsalis larvae in two‐choice tests and the frass of Chrysolina abchasica (Weise) was probably abnormal host selection behaviour. Results indicate that E. daenerys is unlikely to attack non‐target species apart from Eucalyptus‐feeding invasive paropsines (Chrysomelinae). Non‐lethal negative impacts upon less preferred non‐target larvae are possible if E. daenerys does attack them in the field; however, this is likely to be rare.     

Host specificity of Argopistes tsekooni (Coleoptera: Chrysomelidae), a potential biological control agent of Chinese privet

Chinese privet, Ligustrum sinense Lour., is a perennial semi-evergreen shrub that is a serious invasive weed in the United States. Classical biological control offers the best hope for controlling it in an economic, effective, and persistent way. Host specificity of one of the most promising biological control agents of Chinese privet, a flea beetle, Argopistes tsekooni Chen (Coleoptera: Chrysomelidae), was evaluated in China by using laboratory no-choice and choice tests on 13 species of Oleaceae and eight species in other families that have important economic value. In adult no-choice survival and oviposition tests, the flea beetle fed and survived for 30 d on Syringa oblata Lindl., Jasminum nudiflorum Lindl., and three species in the genus Ligustrum. Females also oviposited on these species, but only larvae from eggs laid on S. oblata and Ligustrum spp. developed successfully. In addition, the beetles did not feed or oviposit on the species of economic importance. In choice tests, adults preferred L. sinense for feeding and oviposition. These results show that A. tsekooni is relatively host specific and warrants further testing as a biocontrol agent of Chinese privet in the United States.     

Molecular characterization,virulence and horizontal transmission of Beauveria pseudobassiana from Dendroctonus micans (Kug.) (Coleoptera: Curculionidae)

The great spruce bark beetle, Dendroctonus micans (Kugelann) (Coleoptera: Curculionidae), has been a potential threat for Turkey and the entire Eurasian spruce forests for many years. Control strategies which have been applied so far are still insufficient to prevent its damage. A previous study has shown that a Beauveria isolate (ARSEF 9271) proved to be an efficient microbial control agent against the great spruce bark beetle. In this study, this isolate was identified as B. pseudobassiana based on the partial sequence of EF1‐α and ITS sequence. A conidial suspension (1 × 10⁸/ml) of this fungus caused 100% mortality on both larvae and adults of D. micans within 5 and 6 days, respectively. Also, it caused 100% mycosis value on both larvae and adults. Mortality values of horizontal transmission experiments between larvae and adults which were contaminated with 1 × 10⁶/ml spore suspension at 25%, 50%, 75% and 100% rates were determined as 100% after 15 days at 20°C under the laboratory conditions. We also determined the decrease of the damage in spruce wood block (15 × 25 cm) when the contamination rate of the larvae was increased. Our results indicate that B. pseudobassiana ARSEF 9271 seems to be a very promising biocontrol agent against D. micans.     

Life history and host specificity ofAltica cyanea [Coleoptera: Chrysomelidae], a potential biological control agent for water primrose,Ludwigia adscendens

The life history and host-specificity of the flea beetle,Altica cyanea (Weber) [Coleoptera: Chrysomelidae], were studied to determine its potential value as a biological control agent for water primrose,Ludwigia adscendens (Onagraceae). Females laid a mean of 146 yellowish eggs in masses on this weed and larvae passed through 3 instars. This multivoltine insect completed a generation in 80–84 days. In preliminary host-specificity trials, larvae and adults fed slightly on 2 varieties ofTrapanatans, but they caused considerable damage toLudwigia spp.; no feeding occurred on rice. In host plant choice tests, larvae and adults preferred to feed onL. adscendens andL. prostata toT. natans. In these same tests, onlyLudwigia spp. supported complete development, but it was fastest onL. adscendens. Adults that were reared onL. adscendens lived longer and laid more eggs than those reared onL. prostata, suggesting thatA. cyanea may be a promising biological control agent forL. adscendens growing in rice-paddies. AdultZicrona coerulea L. [Hemiptera: Pentatomidae] preyed upon 3rd instarA. cyanea larvae in the laboratory.      

Diamondback moth oviposition: effects of host plant and herbivory

The oviposition behaviour of Plutella xylostella L. (Lepidoptera: Plutellidae) on Chinese cabbage (Brassica rapa L. Pekinensis, cv. Wombok), canola (Brassica napus L. cv. Thunder TT), and cabbage (Brassica oleracea L. Capitata, cv. sugarloaf) (Brassicaceae) was studied in the laboratory. In no‐choice experiments moths laid most eggs on the stems and lower three leaves of cabbage plants, the lower three leaves of canola plants, but on the upper three leaves of Chinese cabbage plants. The effects of conspecific herbivore damage to foliage could be replicated by mechanical damage. When foliage was damaged, injured cabbage and canola plants were preferred for oviposition over intact conspecifics, whereas injured Chinese cabbage plants were less preferred than intact conspecifics. However, when root tissue was damaged, intact cabbage and canola plants were preferred over injured conspecifics, whereas moths did not discriminate between root‐damaged and intact Chinese cabbage plants. Injury to upper leaves significantly affected the intra‐plant distribution of eggs. In cabbage and canola plants, injury to leaf 6 significantly increased the number of eggs laid on this leaf, resulting in a significant decrease in the number of eggs laid on the lower foliage/stem of plants, whereas in Chinese cabbage plants it significantly decreased the number of eggs laid on leaf 6. Following oviposition on intact plants, neonate larvae established the vast majority of feeding sites on leaves 5–8 in all three host plants, indicating that larvae moved a considerable distance from preferred oviposition sites in cabbage and canola plants. The growth rate of neonates fed on leaf‐6 tissue was significantly greater than that of those fed on leaf‐1 tissue; >90% of larvae completed development when fed exclusively on leaf‐6 tissue but no larvae completed development when fed exclusively on leaf‐1 tissue. The study demonstrates the complex and unpredictable interactions between P. xylostella and its host plants and provides a basis from which we can begin to understand observed distributions of the pest in Brassica crops.     

Influence of cabbage resistance and colour upon the diamondback moth and its parasitoid Oomyzus sokolowskii

Host plant resistance and biological control are vital integrated pest management tools against the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), but to date no study has investigated this system including the DBM parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae). We examined oviposition and development of P. xylostella exposed to two commercial cabbage cultivars (green ‘Chato de quintal’ and red ‘Roxo’) and possible effects upon O. sokolowskii. Under free‐choice tests, DBM females laid significantly more eggs on plants of the green cabbage, even though several population growth parameters showed that DBM developed better on the red cabbage. Furthermore, a laboratory free‐choice test with artificially green‐ and red‐painted kale leaf discs demonstrated a similar oviposition preference pattern, with green colour being preferred over red colour. The preference was apparently visually mediated; olfactometer tests showed similar attraction of moths to both green and red cultivars in choice and non‐choice tests. Host plant cultivar had no statistically significant effect on female parasitoid behaviour towards DBM larvae, nor on parasitoid numbers or longevity. Moreover, wasps parasitizing DBM larvae reared on the green cultivar developed more quickly and in larger numbers per parasitized larva. Thus, feeding on green cabbage rather than red does not hinder, and potentially even enhances, control of DBM by O. sokolowskii. On a practical level, these results suggest that intercalating green cabbage cultivars as a trap crop might help protect more profitable red cultivars in growing fields.     

Direct and indirect effects of a thrips‐transmitted Tospovirus on the preference and fitness of its vector,Frankliniella fusca

Phytoviruses including tospoviruses are known to affect the behavior and fitness of their vectors both positively and negatively. In this study, we investigated the effects of Tomato spotted wilt virus (TSWV) (family Bunyaviridae, genus Tospovirus) infection on the fitness and feeding ability of tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) using peanut, Arachis hypogaea L. (Fabaceae), as a host. Potentially viruliferous F. fusca laid more eggs than non‐viruliferous F. fusca. In contrast, fewer potentially viruliferous F. fusca developed into adults and required a longer developmental time than non‐viruliferous F. fusca, indicating a direct negative effect of the virus on thrips fitness. In addition, no‐choice feeding tests indicated that non‐viruliferous F. fusca fed more rapidly than potentially viruliferous F. fusca. Typically, phytovirus infections are known to enhance the availability of vital nutrients such as free amino acids in infected host plants and to affect other important physiological processes negatively. Free amino acids are known to play a vital role in egg production and development. Further investigations in this study revealed that leaflets of infected plants had ca. 15 times more free amino acids than non‐infected leaflets. TSWV‐infected leaflets were used to rear potentially viruliferous thrips. Higher amino acid levels in TSWV‐infected leaflets than in non‐infected leaflets could have contributed to increased oviposition by potentially viruliferous F. fusca compared to non‐viruliferous F. fusca. Taken together, these results suggest that increased concentrations of free amino acids in TSWV‐infected plants might serve as an incentive for thrips feeding on otherwise unsuitable hosts, thereby facilitating TSWV acquisition and transmission.     

Stage‐dependent responses to emergent habitat heterogeneity: consequences for a predatory insect population in a coffee agroecosystem

Interactions among members of biological communities can create spatial patterns that effectively generate habitat heterogeneity for other members in the community, and this heterogeneity might be crucial for their persistence. For example, stage‐dependent vulnerability of a predatory lady beetle to aggression of the ant, Azteca instabilis, creates two habitat types that are utilized differently by the immature and adult life stages of the beetle. Due to a mutualistic association between A. instabilis and the hemipteran Coccus viridis – which is A. orbigera main prey in the area – only plants around ant nests have high C. viridis populations. Here, we report on a series of surveys at three different scales aimed at detecting how the presence and clustered distribution of ant nests affect the distribution of the different life stages of this predatory lady beetle in a coffee farm in Chiapas, Mexico. Both beetle adults and larvae were more abundant in areas with ant nests, but adults were restricted to the peripheries of highest ant activity and outside the reach of coffee bushes containing the highest densities of lady beetle larvae. The abundance of adult beetles located around trees with ants increased with the size of the ant nest clusters but the relationship is not significant for larvae. Thus, we suggest that A. orbigera undergoes an ontogenetic niche shift, not through shifting prey species, but through stage‐specific vulnerability differences against a competitor that renders areas of abundant prey populations inaccessible for adults but not for larvae. Together with evidence presented elsewhere, this study shows how an important predator is not only dependent on the existence of two qualitatively distinct habitat types, but also on the spatial distribution of these habitats. We suggest that this dependency arises due to the different responses that the predator's life stages have to this emergent spatial pattern.     

Impact of crimson clover dying mulch on two eggplant insect herbivores

Eggplant Solanum melongena L., is often colonized by two early season insect defoliators. The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), and flea beetles Epitrix spp., emerge from their overwintering sites in early spring and seek out emerging host plants such as eggplant. During the 2009 and 2010 growing season, field studies were conducted to investigate the impact of inter‐planting eggplant into a crimson clover (CC), Trifolium incarnatum L., winter cover crop on populations of flea beetles, CPB and their associated arthropod predators. The experiment consisted also of two levels of insecticide usage such as an application of azadirachtins plus pyrethrins followed by several applications of spinosad or no insecticide sprays as subplot treatments. During both study years, significantly fewer (adults, larvae and egg masses) were found on eggplant inter‐planted into CC than in bare‐ground (BG) eggplant plots. Although flea beetle abundance was greater in BG eggplant during 2010, they appeared to be less influenced by the presence of CC than were CPB. Additionally, there was no apparent impact of insecticide treatment on CPB populations on eggplant inter‐planted into CC. However, there was a decline in CPB following treatments with insecticides in BG eggplant plots. This suggests that a winter cover crop such as CC can be used to help manage CPB in eggplant, however, using this tactic in tandem with insecticide sprays may not result in greater CPB management.     

Susceptibility of cold hardy grapes to Drosophila suzukii (Diptera: Drosophilidae)

Drosophila suzukii (Diptera: Drosophilidae), known commonly as spotted wing drosophila, is a vinegar fly originating from South‐East Asia and a major pest to many soft‐skinned fruits. Due to the species recent arrival in North America in 2008, many fruit varieties are yet untested for susceptibility to infestation. While previous work has focused on Vitis vinifera, this study aimed to determine grape susceptibility of cold hardy varieties based on hybrids of V. labrusca, V. riparia and V. vinifera. Field sampling was conducted in Southern Wisconsin (USA) vineyards to establish adult and larval abundance and determine whether the number of adults caught in traps correlates with fruit infestation. Host susceptibility was further assessed through no‐choice bioassays of both intact and damaged fruits. The field study found D. suzukii adults present in all varieties, low larval abundance and no correlation between adult abundance and larval presence. Peak adult abundance occurred mid‐season between veraison and harvest, while larval infestation rates were highest near harvest. In laboratory no‐choice tests, significantly more eggs, larvae and adults occurred in damaged than undamaged grapes. In damaged grapes, larvae and adult abundance was comparable between varieties and to the highly susceptible control of undamaged raspberry; however, D. suzukii developed significantly faster in raspberry than grapes. Fruit characteristics (°Brix, titratable acidity, pH) in grapes were uncorrelated with D. suzukii performance. Together, these findings suggest that cold hardy grapes are overall resistant to D. suzukii if intact and highly susceptible if damaged.     

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.     

Consumption of flea faeces and eggs by larvae of the cat flea,Ctenocephalides felis

The effects of the consumption of flea faeces and non-viable eggs on larval development in the cat flea Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) were investigated. Only 13.3% of larvae developed into adults when fed a diet of male or female flea faeces alone; however, 90% of larvae developed into adults when fed on flea faeces supplemented with non-viable flea eggs. When fed with non-viable eggs alone, larvae did not develop into adults. Nevertheless, non-viable eggs may provide critical supplemental nutrients, lacking in flea faeces and required for larval development. None of the larvae fed on flea faeces or non-viable eggs alone formed a cocoon. A diet of flea faeces alone significantly extended the second as well as third larval stadia compared to larvae fed on diets containing non-viable eggs. It is suggested that the cannibalism of fertile eggs may limit population growth in the cat flea.     

Toxicity of insecticidal soaps to the Asian citrus psyllid and two of its natural enemies

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an important pest of citrus because it transmits plant pathogens responsible for a serious disease of citrus known as huanglongbing. Conventional insecticides are frequently used to manage ACP. Insecticidal soaps (hereafter ‘soaps’) are an insect control option labelled for commercial use as well as for use by homeowners and organic growers. Soaps have been shown to be toxic to some insect pests and therefore might be an alternative to conventional pesticides for control of ACP, but the efficacy of soaps against ACP was largely unknown. Our objective was to test whether different concentrations of two insecticidal soaps, M‐Pede and Safer Insecticidal Soap Concentrate, caused mortality of ACP adults, nymphs and eggs. In addition, we tested whether these soaps were toxic to two natural enemies of ACP, adults of the lady beetle Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae). Direct sprays of M‐Pede or Safer Insecticidal Soap were acutely toxic to ACP adults (regardless of gender) and nymphs when applied in solutions of 0.8–2% in water. Insecticidal soaps were non‐toxic to eggs at rates of up to 2%. Residues of soap were less toxic to adult ACP than direct sprays, even when applied at concentrations of up to 4%. M‐Pede or Safer soap at high concentrations (for example, 2% v/v in water) may be an effective alternative to conventional pesticides to manage adult and nymphal ACP, although multiple applications may be needed if a target population includes eggs. A 2% concentration of either soap applied as a direct spray was non‐toxic to adult C. sanguinea but acutely toxic to adult T. radiata. Soaps therefore may be compatible with biological control of ACP by adult coccinellids but not the parasitoid T. radiata.     

Maternal behaviours may explain riffle‐scale variations in some stream insect populations

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Novel evidence suggests that a ‘Rickettsia felis‐like’ organism is an endosymbiont of the desert flea,Xenopsylla ramesis

Fleas are acknowledged vectors and reservoirs of various bacteria that present a wide range of pathogenicity. In this study, fleas collected from wild rodents from the Negev desert in southern Israel were tested for RickettsiaDNA by targeting the 16S rRNA (rrs) gene. Thirty‐eight Xenopsylla ramesis, 91 Synosternus cleopatrae and 15 Leptopsylla flea pools (a total of 568 fleas) were screened. RickettsiaDNA was detected in 100% of the X. ramesis and in one S. cleopatrae flea pools. None of L. algira flea pools was found positive. All positive flea pools were further characterized by sequencing of five additional genetic loci (gltA, ompB, ompA, htrA and fusA). The molecular identification of the positive samples showed all sequences to be closely related to the ‘Rickettsia felis‐like’ organisms (99–100% similarities in the six loci). To further investigate the association between ‘R. felis‐like’ and X. ramesis fleas, ten additional single X. ramesis adult fleas collected from the wild and five laboratory‐maintained X. ramesis imago, five larva pools (2–18 larvae per pool) and two egg pools (18 eggs per pool) were tested for the presence of ‘R. felis‐like’ DNA. All samples were found positive by a specific ompAPCR assay, confirming the close association of this Rickettsia species with X. ramesis in all its life stages. These results suggest a symbiotic association between ‘Rickettsia felis‐like’ and X. ramesis fleas.     

Generalist dung attraction response in a New Zealand dung beetle that evolved with an absence of mammalian herbivores

1. Dung beetles (Scarabaeidae: Scarabaeinae) are integral parts of many ecosystems because of their role in decomposition of dung; particularly mammal dung, which forms the diet of both larvae and adults. 2. New Zealand dung beetles are unusual as they are flightless and evolved on islands with a highly depauperate mammal fauna and thus without the usual dung resource used by dung beetles elsewhere. The diet of New Zealand dung beetles is unknown. 3. We hypothesised (1) that the endemic dung beetle Saphobius edwardsi would be attracted to a broad range of food types, and (2) that S. edwardsi would be able to survive and reproduce on a range of dung types and puriri (Vitex lucens) humus. 4. Laboratory choice tests identified that S. edwardsi was attracted to a range of mammal, bird, invertebrate, and reptile dung types, but not to non‐dung food sources. Five‐month no‐choice tests found that beetle survival rates were lower for beetles fed with humus compared with those fed on mammal, bird, or invertebrate dung. None of the beetles reproduced. 5. This study suggests S. edwardsi have a strong preference for dung, and are likely to be broad dung generalists in their feeding behaviour.     

Antixenosis and larval and adult dispersal in the Mediterranean corn borer,Sesamia nonagrioides,in relation to Bt maize

Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae) is a key pest of maize [Zea mays L. (Poaceae)] and a main target of Bt maize in the Mediterranean area. To choose the most suitable non‐Bt refuge strategy for preventing or delaying resistance development in this maize borer, we examined its biology and behaviour. No antixenotic effects were found on numbers of eggs and egg batches per plant in choice (Bt vs. non‐Bt plants) and no‐choice assays. However, a greater ratio of young larvae dispersed from Bt than from non‐Bt plants. In addition, larvae that hatched on Bt plants tended to disperse more than those that hatched on non‐Bt plants, particularly during young growth stages. Many adults, especially females, could fly at least up to 400 m, as was found in a dispersal study with rubidium‐marked adults. The stimulation of larval dispersal by the Bt trait and the dispersal capacity of adults might compromise the efficacy of seed mixtures as an insecticide resistance management strategy.