Presence Of Parasitoids Research Articles

Uji Alat Augmentasi dan Konservasi Parasitoid Telur Kepik Hijau (Nezara viridula L.) pada Tanaman Kedelai (Glycine max L.)

Soybean pod damage caused by N. viridula reached 61.37% of the total pods and 61.67% of the total seeds attacked. Efforts were made, namely the application of chemical insecticides made from active chlorpyrifos which can reduce the population of N. viridula to reach 57.4% and the insecticides made from deltamerin which are reducing the population by 51.6%. Control is needed that can reduce the negative effects caused by chemical insecticides, one of which is mechanical control. Mechanical control can be done one of them with augmentation and conservation tools. the research is by taking the eggs of N. viridula in the field and laying the eggs in an augmentation and conservation tool with several treatments of different filter cloth diameters, 0.1 mm; 0.3 mm; 0.2 mm; and 0.6 mm. Observations were made by looking at and counting the number of parasitoids that were able to pass through the filter cloth and those that did not pass through the filter cloth, followed by identification of the species of the parasitoid that was obtained. The results showed that the parasitoids were able to escape in all treatments but with varying amounts. The difference in number can be influenced by the presence of parasitoids in the field and the level of parasitoid parasitation. Likewise with Trichogramma sp also able to pass on all treatments. Therefore, the most suitable treatment is treatment with a 0.1 mm diameter filter cloth. The identified parasites were T. rowani and T. podisi

Prior adaptation of parasitoids improves biological control of symbiont-protected pests.

There is increasing demand for sustainable pest management to reduce harmful effects of pesticides on the environment and human health. For pest aphids, biological control with parasitoid wasps provides a welcome alternative, particularly in greenhouses. However, aphids are frequently infected with the heritable bacterial endosymbiont Hamiltonella defensa, which increases resistance to parasitoids and thereby hampers biological control. Using the black bean aphid (Aphis fabae) and its main parasitoid Lysiphlebus fabarum, we tested whether prior adaptation of parasitoids can improve the control of symbiont‐protected pests. We had parasitoid lines adapted to two different strains of H. defensa by experimental evolution, as well as parasitoids evolved on H. defensa‐free aphids. We compared their ability to control caged aphid populations comprising 60% unprotected and 40% H. defensa‐protected aphids, with both H. defensa strains present in the populations. Parasitoids that were not adapted to H. defensa had virtually no effect on aphid population dynamics compared to parasitoid‐free controls, but one of the adapted lines and a mixture of both adapted lines controlled aphids successfully, strongly benefitting plant growth. Selection by parasitoids altered aphid population composition in a very specific manner. Aphid populations became dominated by H. defensa‐protected aphids in the presence of parasitoids, and each adapted parasitoid line selected for the H. defensa strain it was not adapted to. This study shows, for the first time, that prior adaptation of parasitoids improves biological control of symbiont‐protected pests, but the high specificity of parasitoid counter‐resistance may represent a challenge for its implementation.

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Host density and parasitoid presence interact and shape the outcome of a tritrophic interaction on seeds of wild lima bean

The interaction between the seed beetle Zabrotes subfasciatus and its parasitoid Stenocorse bruchivora, was investigated on seeds of two populations of wild lima bean, Phaseolus lunatus. By manipulating the number of beetle larvae per seed and the presence of parasitoids, we determined how factors related to beetle larvae density, the seed in which they feed and the parasitoid, may interact and affect host and parasitoid survival. Results showed that an increase in larval beetle density had a negative impact on beetle performance. This effect cascaded up to parasitoids, high larval density strongly reduced parasitoid emergence. Also, parasitoid presence resulted in faster beetle development and lower female weight. An interactive effect between larval host density and parasitoid presence affected the number of insects that emerged from the seeds. Beetle performance was better in the bean population with the largest seeds, while parasitoid emergence was the lowest in these seeds. This study shows that the impact of parasitoids on seed beetles is contingent on the interaction between density-mediated (direct mortality) and trait-mediated (e.g. non-consumptive) effects. Indirect trait-mediated effects of natural enemies are likely prevalent across insect communities, understanding their role in driving host-parasitoid interactions can have important implications for biological control.

Impact of a shared sugar food source on biological control of Tuta absoluta by the parasitoid Necremnus tutae

Honeydew is a sugar-rich food source produced by sap-feeding insects, notably by major pests such as aphids and whiteflies. It is an important alternative food source for the adult stage of various key natural enemies (e.g., parasitoids), but it may be used also as food by agricultural pests. Necremnus tutae is an idiobiont parasitoid, and it is the most abundant larval parasitoid associated with the South American tomato pinworm, Tuta absoluta, in recently invaded European areas. The impact of N. tutae on T. absoluta populations was evaluated under greenhouse conditions with and without the presence of a honeydew producer, the aphid Macrosiphum euphorbiae. In addition, laboratory experiments were performed to evaluate the longevity of N. tutae and T. absoluta adults when fed with water, honey or honeydew produced by the aphid. In the greenhouse, N. tutae effectively reduced T. absoluta population by the end of the experiment, and this independently of the presence of the aphid; still the presence of M. euphorbiae led to delayed and reduced T. absoluta population peak when controlled by the parasitoid (there was a fourfold increase in parasitoid density in presence of aphid). The longevity of both N. tutae and T. absoluta females increased in the presence of honeydew (when compared to water only) under laboratory conditions; it hinted that honeydew could be used by an herbivore as T. absoluta. The interactions between the two phytophagous species showed contrasting effects, and this mostly independently of parasitoid presence. Tuta absoluta had no impact on aphid population dynamics. By contrast, the production of T. absoluta larvae was higher in the first part of the experiment as the adults lived longer (feeding on aphid honeydew) and produced more larvae. In the second part of the experiment, there were fewer T. absoluta larvae in the presence of the aphid, likely owing to resource competition and/or negative plant-mediated indirect interactions. We demonstrated that honeydew producers could impact parasitoid-host population dynamics both through direct and indirect interactions and that potential positive effects of a sugar food source toward a pest can be nullified in the long term by other negative effects occurring simultaneously.

Landscape structure and parasitoid diversity as measures of sustainable landscape

Complexity and structure of a landscape influence the presence of insect parasitoids in agricultural landscapes. Landscape structures are often formed from semi-natural habitat fragmentation, which can reduce the richness and abundance of insect parasitoid and affect their ability to suppress pest population. This study was aimed to study the effect of landscape structure on the diversity and abundance of insect parasitoids in long beans fields. In six agricultural regions, landscape parameters were calculated, i.e class area (CA), a number of patches (NumP), and mean patch size (MPS). Insect samplings were conducted using transect methods and direct collection. Results of landscape complexity did not affect the species richness of parasitoid, but it did affect the species composition. The results showed that the higher the CA of the tree, the higher the percentage of parasitization, but the higher the CA of agriculture, the lower the percentage of parasitization. This shows that there are landscape parameter indicators that can be used as a key to see the presence of parasitoids so that they can provide an indication of sustainability. Therefore, landscape structure must consider the importance of landscape management habitats for the conservation of natural enemies especially insect parasitoid as a biological control agent to create sustainable landscapes.

A molecular tool to identify Anastatus parasitoids of the brown marmorated stink bug

AbstractGlobally, Anastatus species (Hymenoptera: Eupelmidae) are associated with the invasive agricultural pest Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). In Europe, the polyphagous Anastatus bifasciatus (Geoffroy) is the most prevalent native egg parasitoid on H. halys eggs and is currently being tested as a candidate for augmentative biological control. Anastatus bifasciatus frequently displays behavior without oviposition, and induces additional host mortality through oviposition damage and host feeding that is not measured with offspring emergence. This exacerbates accurate assessment of parasitism and host impact, which is crucial for efficacy evaluation as well as for pre‐ and post‐release risk assessment. To address this, a general Anastatus primer set amplifying a 318‐bp fragment within the barcoding region of the cytochrome oxidase I (COI) gene was developed. When challenged with DNA of three Anastatus species —A. bifasciatus, Anastatus japonicus Ashmead, and Anastatus sp.—, five scelionid parasitoid species that might be encountered in the same host environments and 11 pentatomid host species, only Anastatus DNA was successfully amplified. When applied to eggs of the target host, H. halys, and an exemplary non‐target host, Dendrolimus pini L. (Lepidoptera: Lasiocampidae), subjected to host feeding, no Anastatus amplicons were produced. Eggs of the two host species containing A. bifasciatus parasitoid stages, from 1‐h‐old eggs to pupae, and emerged eggs yielded Anastatus fragments. Confirmation of parasitoid presence with dissections and subsequent PCRs with the developed primer pair resulted in 95% success for 1‐h‐old parasitoid eggs. For both host species, field‐exposed sentinel emerged eggs stored dry for 6 months, 100% of the specimens produced Anastatus amplicons. This DNA‐based screening method can be used in combination with conventional methods to better interpret host‐parasitoid and parasitoid‐parasitoid interactions. It will help address ecological questions related to an environmentally friendly approach for the control of H. halys in invaded areas.

The Contribution of Surrounding Margins in the Promotion of Natural Enemies in Mediterranean Apple Orchards.

(1) Habitat management can enhance beneficial arthropod populations and provide ecosystem services such as biological control. However, the implementation of ecological infrastructures inside orchards has a number of practical limitations. Therefore, planting/growing insectary plants in the margins of orchards should be considered as an alternative approach. (2) Here, we assessed the efficacy of a flower margin composed by four insectary plant species (Achillea millefolium, Lobularia maritima, Moricandia arvensis and Sinapis alba), which was placed on an edge of four Mediterranean apple orchards to attract natural enemies of two apple tree aphids (Dysaphis plantaginea and Eriosoma lanigerum). We also characterized the natural enemies present in the aphid colonies. (3) Our results show that the implementation of a flower margin at the edge of apple orchards attracts predators (Syrphidae, Thysanoptera, Araneae, Heteroptera, Coleoptera) and parasitoids. Parasitoids are the main natural enemies present in aphid colonies in our area. (4) The implementation of the flower margins successfully recruited natural enemy populations, and the presence of parasitoids in the surroundings of the orchards increased the parasitism of D. plantaginea colonies.

Nest site choice by the intertidal spider Desis formidabilis (Araneae: Desidae) and nest utilisation by its hymenopteran egg parasitoid

1. Echthrodesis lamorali Masner, 1968 is the only known parasitoid of the eggs of the intertidal rocky shore spider Desis formidabilis O.P. Cambridge 1890 and is endemic to a small area of South Africa.2. The abundance of spider nests and parasitoid presence were assessed in relation to their in‐ and between‐shore location at multiple sites within the distribution of E. lamorali along the Cape Peninsula (Western Cape, South Africa).3. Desis formidabilis nests were more abundant in the mid‐shore zone than higher up or lower down the shore. Spider population sizes also differed between collection sites, with higher numbers recorded on the cooler western coast of the peninsula.4. Evidence of parasitoid activity was recorded in 43.31% of the 127 nests and 13.85% of the 592 egg sacs they contained.5. Where parasitoids gained entry to a spider egg sac, oviposition took place into all of the eggs present.6. Incidence of wasp activity was positively correlated with spider nest concentration, not with height up the shore, suggesting that both the host and parasitoid are tolerant of salt‐water inundation.7. These results should assist managers of the Table Mountain National Park, in which the full distribution of E. lamorali falls, to better understand this component of rocky shore community dynamics.

Influence of the margin vegetation on the conservation of aphid biological control in apple orchards

The influence of three margin strip treatments (wildflower strips, grass strips and spontaneous vegetation) adjacent to apple orchards on the biological control of Dysaphis plantaginea Passerini (Hemiptera: Aphididae) was compared during two consecutive years. The wildflower strips provided the highest amount of floral resources. Within the margin strips, hoverflies responded positively to higher resource provisioning whereas ladybird abundance did not differ between strip treatments. Within the orchards, the presence of parasitoids, hoverflies, and ladybirds in aphid colonies and the predation of sentinel aphids were not significantly affected by the adjacent strip treatments. The number of natural enemies observed in aphid colonies was mainly driven by aphid number. Aphid numbers were higher close to the margin strips suggesting that aphid colonization from orchard edges may counteract the positive effect of wildflower strips on natural enemy abundance and on a reduction of aphid infestation. The results confirm the positive influence of floral resource provisioning by wildflower strips on the conservation of aphid natural enemies, but also suggest that effects of wildflower strips on aphid regulation inside orchards are not very strong compared with spontaneous vegetation naturally occurring in the margins.

Does urbanization explain differences in interactions between an insect herbivore and its natural enemies and mutualists?

Urbanization can alter the composition of arthropod communities. However, little is known about how urbanization affects ecological interactions. Using experimental colonies of the black bean aphid Aphis fabae Scopoli reared on Vicia faba L, we asked if patterns of predator-prey, host-parasitoid and ant-aphid mutualisms varied along an urbanization gradient across a large town in southern England. We recorded the presence of naturally occurring predators, parasitoid wasps and mutualistic ants together with aphid abundance. We examined how biotic (green areas and plant richness) and abiotic features (impervious surfaces and distance to town center) affected (1) aphid colony size, (2) the likelihood of finding predators, mutualistic ants and aphid mummies (indicating the presence of parasitoids), and (3) how the interplay among these factors affected patterns of parasitoid attack, predator abundance, mutualistic interactions and aphid abundance. Aphid abundance was best explained by the number of mutualistic ants attending the colonies. Aphid predators responded negatively to both the proportion of impervious surfaces and to the number of mutualistic ants farming the colonies, and positively to aphid population size, whereas parasitized aphids were found in colonies with higher numbers of aphids and ants. The number of mutualistic ants attending was positively associated with aphid colony size and negatively with the number of aphid predators. Our findings suggest that for insect-natural enemy interactions, urbanization may affect some groups, while not influencing others, and that local effects (mutualists, host plant presence) will also be key determinants of how urban ecological communities are formed.

Defensive symbionts mediate species coexistence in phytophagous insects

Abstract Competition of two species for the same resource is expected to result in competitive exclusion of the inferior competitor. In natural communities, however, other antagonists and symbionts moderate competition. Thus, we have to go beyond studying pairwise interactions. Natural enemies may facilitate coexistence if they affect the superior competitor more strongly, or they can hinder coexistence via apparent competition. Less well studied is the role of symbionts, which may influence species coexistence in conjunction with enemies. Eukaryotes commonly harbour microbial endosymbionts that provide protection against natural enemies, but are costly in their absence. Such defensive symbionts could thus mediate coexistence of species competing for the same resource, both in the presence and in the absence of enemies, but as yet there is little evidence for this claim. We addressed this proposed role of defensive symbionts in replicated simple communities consisting of two aphid species sharing the same host plant and the same natural enemy, a parasitoid wasp. Both, one, or neither species were infected with a resistance‐conferring symbiont, and they competed in the absence as well as the presence of parasitoids. The symbiont had significant effects in the absence of parasitoids by lowering competitive ability especially in one species, but the effects were more dramatic in the presence of parasitoids. With both species protected by the symbiont, parasitoid densities remained low and both aphid species persisted. When neither species was protected, parasitoids drove both species to extinction. Surprisingly, the same outcome was observed when only one species was protected. The susceptible species supported high densities of parasitoids that also killed the resistant aphids via mechanisms other than parasitism, presumably by disturbing them to the point of starvation. This is an intriguing form of apparent competition. Our results demonstrate an important role of defensive symbionts in insect communities through modifying species interactions. This highlights the need for experimental data when studying species coexistence in competitive networks. Furthermore, the observation that a susceptible host can negatively affect a resistant host via a shared parasitoid is an instructive insight for biological control. A plain language summary is available for this article.

Population dynamics of Arthroschista hilaralis pest and its parasitoid diversity in various jabon (Anthocephalus cadamba) cropping patterns in South Sumatra, Indonesia

Utami S, Triwidodo H, Pudjianto, Rauf A, Haneda NF. 2018. Population dynamics of Arthroschista hilaralis pest and its parasitoid diversity in various jabon (Anthocephalus cadamba) cropping patterns in South Sumatra, Indonesia. Biodiversitas 19: 239-245. Jabon (Anthocephalus cadamba), a native tree species in Indonesia exhibit natural distribution, spreading over an enormous area in this region. In South Sumatra, jabon has long been cultivated in both communities and industrial plantation forests. Arthroschista hilaralis (Lepidoptera: Pyralidae) is the most damaging insect pest of jabon in South Sumatra. This study analyzed the population dynamics of A. hilaralis in jabon monoculture and two agroforestry systems, and assessed the diversity of the pest parasitoids and their parasitism level on A. hilaralis. Our results showed that planting systems, climatic factors, and the presence of parasitoids could significantly affect the population dynamics of A. hilaralis; its mean population density was highest in monocultures plantation during the rainy season compared with population densities in agroforestry systems. Three parasitoids species attacking A. hilaralis were found in these agroforestry systems, including Phanerotoma sp., Apanteles sp. and Brachymeria sp., while only one species (Apanteles sp.) was found in a monoculture. The rate of parasitization of A. hilaralis within agroforestry systems was higher than in monocultures, and the level of larval parasitization by Apanteles sp. in the agroforestry system was higher in instar 1 than in other larval stages.

With or without you: Effects of the concurrent range expansion of an herbivore and its natural enemy on native species interactions.

Global climatic changes may lead to the arrival of multiple range-expanding species from different trophic levels into new habitats, either simultaneously or in quick succession, potentially causing the introduction of manifold novel interactions into native food webs. Unraveling the complex biotic interactions between native and range-expanding species is critical to understand the impact of climate change on community ecology, but experimental evidence is lacking. In a series of laboratory experiments that simulated direct and indirect species interactions, we investigated the effects of the concurrent arrival of a range-expanding insect herbivore in Europe, Spodoptera littoralis, and its associated parasitoid Microplitis rufiventris, on the native herbivore Mamestra brassicae, and its associated parasitoid Microplitis mediator, when co-occurring on a native plant, Brassica rapa. Overall, direct interactions between the herbivores were beneficial for the exotic herbivore (higher pupal weight than the native herbivore), and negative for the native herbivore (higher mortality than the exotic herbivore). At the third trophic level, both parasitoids were unable to parasitize the herbivore they did not coexist with, but the presence of the exotic parasitoid still negatively affected the native herbivore (increased mortality) and the native parasitoid (decreased parasitism rate), through failed parasitism attempts and interference effects. Our results suggest different interaction scenarios depending on whether S. littoralis and its parasitoid arrive to the native tritrophic system separately or concurrently, as the negative effects associated with the presence of the parasitoid were dependent on the presence of the exotic herbivore. These findings illustrate the complexity and interconnectedness of multitrophic changes resulting from concurrent species arrival to new environments, and the need for integrating the ecological effects of such arrivals into the general theoretical framework of global invasion patterns driven by climatic change.

No evidence of an immune adjustment in response to a parasitoid threat in Lobesia botrana larvae

Immune function is a key determinant of an organism’s fitness, and natural insect populations are highly variable for this trait, mainly due to environmental heterogeneity and pathogen diversity. We previously reported a positive correlation between infection prevalence by parasitoids and host immunity in natural populations of the vineyard pest Lobesia botrana. Here, we tested whether this correlation reflects a plastic adjustment of host immunity in response to the local presence of parasites. To this end, we measured immunity of non-parasitized L. botrana larvae exposed, respectively, to one of the two most common species of parasitoids in vineyards, over 6days. Larvae were able to sense the parasitoid through visual, chemical, or mechanical cues, but contact larvae-parasitoid were excluded. Contrary to our hypothesis, we found that L. botrana larvae did not increase their immune defenses in the presence of parasitoids, despite their ability to sense a potential threat. Our results therefore suggest that the positive correlation between infection prevalence by parasitoids and L. botrana immunity among natural populations may result from micro-evolutionary changes resulting from long-term local selection pressures imposed by parasitoids in wild populations rather than plastic adjustments of immunity.

The invasive pest Drosophila suzukii uses trans-generational medication to resist parasitoid attack

Animal medication is a behavioral strategy to resist enemies based on the use of substances from the environment. While it has been observed in several animals, whether invasive species can use medication to resist new enemies during its expansion is unknown. Here, we show that the worldwide invasive pest Drosophila suzukii performs trans-generational prophylactic medication by adapting its oviposition behavior in the presence of enemies. We find that flies preferentially lay their eggs on media containing atropine – an entomotoxic alkaloid – in the presence of parasitoids. We further show that flies developing on atropine more efficiently resist parasitization by parasitoids. Finally, we find that developing in hosts reared on atropine strongly impacts the life-history traits of parasitoids. This protective behavior is reported for the first time in a pest and invasive species, and suggests that animal medication may be an important driver of population dynamics during invasions.

Tri‐trophic ecology of native parasitic nest flies of birds in Tobago

AbstractIntroduced parasites threaten host populations around the world. For example, introduced parasitic nest flies (Philornis downsi) have contributed to the decline of several species of Darwin's finches in the Galápagos Islands. Introduced parasites are thought to have severe effects on native hosts because the hosts do not have effective defenses against such parasites and/or because introduced parasites have escaped the native enemies that keep their own populations in check. Studying effects of parasites on native hosts is an essential step in testing these causal hypotheses. We conducted a field experiment to assess the virulence of a native species of Philornis (Philornis trinitensis), which parasitizes birds on the island of Tobago. We manipulated flies in nests of black‐faced grassquits (Tiaris bicolor), a close relative of Darwin's finches, as well as tropical mockingbirds (Mimus gilvus), a congener of the Galápagos mockingbird (Mimus parvulus). We predicted that P. trinitensis would be relatively avirulent because its native hosts in Tobago have had time to evolve effective defenses against it. We also noted the presence of parasitoids and other enemies of Philornis in Tobago nests. Surprisingly, effects of native P. trinitensis on Tobago birds were similar to the effects of introduced P. downsi on birds in the Galápagos. Flies reduced the reproductive success of grassquits, but not mockingbirds, which are also relatively unaffected by Philornis in the Galapagos. Thus, native Philornis flies are not less virulent than introduced flies. The prevalence of Philornis in Tobago was lower than the prevalence of Philornis in the Galápagos. Presumed enemies of Philornis (parasitoid wasps and ants) were relatively common in nests of birds in Tobago, but largely absent from nests in the Galápagos. We suggest that introduced P. downsi in the Galápagos is widespread, not because hosts lack defenses, but because it has left its enemies behind.

Uncovering Trophic Interactions in Arthropod Predators through DNA Shotgun-Sequencing of Gut Contents.

Characterizing trophic networks is fundamental to many questions in ecology, but this typically requires painstaking efforts, especially to identify the diet of small generalist predators. Several attempts have been devoted to develop suitable molecular tools to determine predatory trophic interactions through gut content analysis, and the challenge has been to achieve simultaneously high taxonomic breadth and resolution. General and practical methods are still needed, preferably independent of PCR amplification of barcodes, to recover a broader range of interactions. Here we applied shotgun-sequencing of the DNA from arthropod predator gut contents, extracted from four common coccinellid and dermapteran predators co-occurring in an agroecosystem in Brazil. By matching unassembled reads against six DNA reference databases obtained from public databases and newly assembled mitogenomes, and filtering for high overlap length and identity, we identified prey and other foreign DNA in the predator guts. Good taxonomic breadth and resolution was achieved (93% of prey identified to species or genus), but with low recovery of matching reads. Two to nine trophic interactions were found for these predators, some of which were only inferred by the presence of parasitoids and components of the microbiome known to be associated with aphid prey. Intraguild predation was also found, including among closely related ladybird species. Uncertainty arises from the lack of comprehensive reference databases and reliance on low numbers of matching reads accentuating the risk of false positives. We discuss caveats and some future prospects that could improve the use of direct DNA shotgun-sequencing to characterize arthropod trophic networks.

KAPPA FUNCTION AS A UNIFYING FRAMEWORK FOR DISCRETE POPULATION MODELING

AbstractThis paper develops a unified way to describe the various generalized discrete‐time nonlinear dynamical models with density dependence, Allee effects, and parasitoids. We show how the kappa function can be used to describe the probabilities involved in intra‐ or interspecific encounters, namely, (i) the probability of surviving to the next generation in the absence of parasitoids or Allee effects, (ii) the encounter probability associated with Allee effects, and (iii) the probability of escaping parasitism in the presence of parasitoids. Having introduced a phenomenological framework of modeling via the kappa function, we then provide a realistic mechanism through stochastic encounters, responsible for generating the kappa function to any of the three involved probabilities. The unified modeling through the kappa function yields insights into how abundances influence species interactions. It is now straightforward to use this unified modeling to analyze and investigate its consequences in species dynamics.

Euxesta spp. NUEVA PLAGA EN Zea mayz L. VARIEDAD rugosa: ASOCIACIÓN CON ATAQUES DE Heliothis zea EN SIEMBRAS DE PRIMAVERA Y VERANO

<p>The "corn silk fly" of maize (<em>Euxesta</em> spp. Loew, 1868) appeared in 2005 in Santa Fe (Argentina), causing damage to the ears. The attacks are related to temperature, crop growth stage and previous attack of other pests. For this new pest, we determined the species present, the damage on Bt sweet corn plantings in two seasons (August and February), the association of attacks with <em>Heliothis zea</em> (Boddie, 1850) and the presence of parasitoids. Larvae counts of <em>H. zea</em> and <em>Euxesta</em> spp. began in the phenological stage of R2 and ended in R5 and consisted of removing at random from each batch (three for each planting season) four ears. In laboratory we determined the percentage of damage on the ears and number of larvae of <em>Euxesta </em>spp. and <em>H. zea</em>, discriminated by size. Fly was identified as <em>E. eluta</em>, damage was greatest in the early spring planting corn. Attacks were correlated with <em>H. zea</em>.</p>