scholarly journals Keep your enemies closer: enhancing biological control through individual movement rules to retain natural enemies inside the field

Web Ecology ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Thomas Delattre ◽  
Blanche Collard ◽  
Claire Lavigne

Abstract. Biological control of pests aims at lowering population levels of pest species by favouring natural enemies, in order to reduce the use of pesticides. The movement behaviour of natural enemies is decisive in the success of biological control: when low habitat quality hinders the diffusion of natural enemies from the border, the density of natural enemies may frequently be heterogeneous inside agricultural plots. We hypothesise that the specific relationship between habitat quality and movement behaviour may allow the improvement of biological control by means of a careful allocation of habitat qualities inside and around the plot. We used three tested individual-based movement models, with different levels of complexity ranging from simple cell-to-cell movements to complex strategies including the sinuosity of the path, boundary crossings, perceptual range, and directional persistence. We used the models to explore how the manipulation of habitat quality may allow significant improvements to the residence time of natural enemies inside the field. We suggest that existing field designs are generally inadequate to retain natural enemies. Mechanistic explanations leading to the highest and lowest residence times are used to draw specific management recommendations.

2018 ◽  
Vol 10 (7) ◽  
pp. 167 ◽  
Author(s):  
Angélica Massarolli ◽  
Ana Regina Lucena Hoffmann ◽  
Bruna Magda Favetti ◽  
Alessandra Regina Butnariu

Studies on natural enemies are important to find new species and to develop management strategies to preserve them to help control pests in biological control programs. For the state of Mato Grosso, Brazil, which comprises the Amazon, Cerrado, and Pantanal biomes, few studies have been conducted on the diversity of these parasitoids, possible endemic and/or new species, as well as their potential as natural enemies. Thus, the present study was aimed at describing the diversity of parasitoids of the families Ichneumonidae (Hymenoptera) and Tachinidae (Diptera) associated with pest lepidopterans in soybean crops. Weekly sampling of pest lepidopterans was carried out during four soybean seasons (2009/2010, 2010/2011, 2011/2012 and 2012/2013). Parasitoid larvae were observed in the main lepidopteran pest species of soybean during the four soybean seasons. Three genera of the Ichneumonidae family, belonging to the genera Microcharops Roman, Ophionellus Westwood, and Podogaster Brullé. Six genera of the Tachinidae family occur in the state of Mato Grosso in soybean fields. The following genera were recorded: Archytas spp. Jaennicke, Phorocera spp. Robineau-Desvoidy, Gymnocarcelia spp. Townsend, Lespesia spp. Robineau-Desvoidy, Eucelatoria spp. Townsend, Chetogena spp. Rondani. These parasitoids were found parasitizing caterpillars of the Noctuidae (Lepidoptera), in species that had not yet been reported as hosts for the Neotropical region. Further studies are needed on the beneficial entomofauna and their preservation in agricultural environments.


Author(s):  
Joakim Pålsson ◽  
Mario Porcel ◽  
Teun Dekker ◽  
Marco Tasin

AbstractThe widespread use of pesticides along with the simplification of the landscape has had undesirable effects on agroecosystems, such as the loss of biodiversity and the associated ecosystem service biological control. How current production systems can be remodelled to allow for a re-establishment of biological pest control, while preserving productivity, is a major challenge. Here, we tested whether a combination of tools could augment or synergize biological control of insect pests in apple (Malus domestica), comprised of a tortricid pest complex, a geometrid pest complex and the rosy apple aphid. The tools aimed at disrupting mating behaviour of multiple pest species (multispecies mating disruption, “Disrupt”, MMD), attracting natural enemies (a blend of herbivory-induced volatiles, “Attract”, A), or providing refuge and rewards for a diverse insect community (perennial flower strip, “Reward”, R) over a 3-year period. Suction samples were consistently richer in generalist predators but not in parasitoids when multiple tools including MMD + A + R or MMD + A were employed. In addition, lepidopteran pest levels were significantly lower in these plots than in MMD or MMD + R at the end of the 3-year experiment. This was, however, not reflected in survival of artificially established aphid colonies. Our data indicates that multiple, complementary tools can greatly enhance natural enemy level, but also that long-term implementation is needed to fully realize the augmentatory or synergistic potential of complementary components and restore biological control as an ecosystem service of practical relevance.


2004 ◽  
Vol 39 (3) ◽  
pp. 433-443 ◽  
Author(s):  
Michael P. Seagraves ◽  
Robert M. McPherson ◽  
John R. Ruberson

The red imported fire ant, Solenopsis invicta Buren, reportedly contributes to the biological control of key soybean pests. However, S. invicta may negatively affect ground-dwelling natural enemies such as ground beetles and earwigs. Information on the interactions between natural enemies is important for anticipating the success of biological control in agroecosystems with multiple interacting entomophagous species. Ground arthropods were monitored in soybean using pitfall traps in the 2000 and 2001 growing seasons to determine their response to selected fire ant controls. Three treatments were examined: an untreated check, Amdro™ (hydramethylnon) bait (ant-specific), and Lorsban™ (chlorpyriphos) (broad spectrum) plus Amdro. Fire ant captures in pitfall traps were lower in the Amdro and in the Amdro plus Lorsban treatments compared to the untreated control. Reduced fire ant density plus chemical treatment impacted the abundance of certain ground predators. Spiders, primarily Lycosidae, were significantly more abundant in the untreated control plots on some sampling dates; whereas, the earwig Labidura riparia Pallas was more abundant in the Lorsban and Amdro plots, presumably due to the removal of fire ants and other natural enemies. Ground beetles (Carabidae) were not different between treatments on any sampling dates. This study supports the assumption that spiders are compatible with fire ants as natural enemies and that earwigs are not compatible with fire ants. Numbers of lesser cornstalk borer, Elasmopalpus lignosellus Zeller, were not affected by the suppression of fire ant predation or the chemical treatments in 2000, the only year when they were captured. Crickets (Gryllidae), mole crickets (Gryllotalpridae), click beetles (Elateridae), scarab beetles (Scarabaeidae), and false darkling beetles (Melandryidae) also were not different between the fire ant suppression treatments.


Author(s):  
Patricia J. Vittum

This chapter assesses biological control strategies that can reduce turfgrass insect pest populations. Biological control refers to the suppression of pest populations through the activity of living organisms or their by-products. Although a majority of this book is devoted to understanding turfgrass pests, most organisms associated with turfgrass are not pests but instead may be considered beneficial because they reduce thatch, help recycle soil nutrients, or are natural enemies of pest species. Pest outbreaks can sometimes be traced to the absence of natural control agents in the turf environment. Vertebrate and invertebrate predators, insect parasitoids, and microbial pathogens may act as natural enemies of turfgrass pests. Although the effect of one species of natural enemy may be minor, the combined effects of predators, parasitoids, and pathogens can cause considerable reductions in pest populations. Additional agents can be considered as biological controls. These include fungal endophytes (which confer host-plant resistance to some insects), botanicals (botanically derived insecticides), and synthetic compounds that mimic the activity of insect-produced compounds, such as growth hormones and pheromones.


2016 ◽  
Author(s):  
◽  
Kathryn Suzanne Ingerslew

Predators are typically evaluated for their potential effectiveness as natural biological control agents by examining traits related to their consumptive relationship with an herbivore. For example, voracious predators with a high prey attack rate or predators that specialize in consuming a particular pest species are considered ideal for biological control. However, there is a growing body of research demonstrating that predators also influence herbivore population size through non-consumptive interactions. Non-consumptive interactions include changes in prey behavior, morphology, or life-history traits in response to the presence of a predator that allow prey to survive a predator encounter but result in declines in prey fitness due to reduced availability of resources or expending energy that would have been otherwise used for growth or reproduction. The existence of non-consumptive effects is significant because it raises the possibility that a non-lethal organism (i.e. non-enemy) in the environment can also contribute to herbivore suppression if an herbivore inaccurately perceives an organism as a threat and engages in a defensive response. The goal of my dissertation research was to determine whether non-enemies contribute to natural biological control and enhance herbivore suppression beyond levels accomplished by consumptive natural enemies alone. Previous work in our lab demonstrated that pea aphids Acyrthosiphon pisum (Harris) respond to the non-enemy wasp Aphidius colemani Viereck by stopping feeding and dropping off of their host plant, resulting in a decline in pea aphid abundance even though pea aphids are not a host for A. colemani. My work evaluated whether this behavioral suppression of pea aphid populations by the non-enemy wasp is complementary with pea aphid suppression by the consumptive enemy Aphidius ervi Haliday. I investigated 1) the mechanisms responsible for and the magnitude of the non-consumptive effects of A. colemani and A. ervi on pea aphid populations, 2) the contributions of non-consumptive interactions to short-term and long-term suppression of aphid populations in the presence of consumptive natural enemies, and 3) the feasibility of increasing plant diversity in the field to enhance pea aphid suppression by facilitating behavioral non-consumptive interactions. I found that pea aphids respond to interactions with both wasp species, but they more frequently engaged in defensive behaviors such as dropping in the presence of the enemy A. ervi than the non-enemy A. colemani. The behavioral response of the pea aphid to the presence of the non-enemy was strong enough for A. colemani to suppress pea aphid populations in the short term, but this suppression was not maintained over the long term. When the non-enemy A. colemani was combined with the consumptive enemy A. ervi, there was some evidence for antagonism between the wasps over the short term. However, the non-enemy and enemy were complementary in their suppression of pea aphid populations over the long term, with more consistent and stable suppression when both wasps were present. I also demonstrated that increasing plant diversity in a field setting enhances suppression of pea aphid populations by promoting interactions between pea aphids and non-enemies. My work demonstrates that non-lethal organisms, or non-enemies, in the environment have an important role to play in influencing herbivore abundance, and that the addition of non-enemies to a community of lethal predators and parasitoids can lead to greater and more consistent suppression of herbivores in the long term.


EDIS ◽  
2017 ◽  
Vol 2017 (6) ◽  
Author(s):  
James P. Cuda ◽  
Patricia Prade ◽  
Carey R. Minteer-Killian

In the late 1970s, Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), was targeted for classical biological control in Florida because its invasive properties (see Host Plants) are consistent with escape from natural enemies (Williams 1954), and there are no native Schinus spp. in North America. The lack of native close relatives should minimize the risk of damage to non-target plants from introduced biological control agents (Pemberton 2000). [...]


2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Hosam M. K. H. El-Gepaly

AbstractSorghum panicles offer a very rich microenvironment for many insect pest species and their natural enemies. Thirty arthropod species belonging to 28 families, pertaining to 9 orders were obtained from sorghum panicles planted in Sohag Governorate, Egypt, during the 3 successive seasons of 2016–2018. Out of these species were 14 pests, 16 predators, and 3 parasitoids. Lepidopteran and hemipteran pests were the most dominant species-infested sorghum-panicles during the mature stages of the panicles. Three microlepidopteran pests, the noctuid, Eublemma (Autoba) gayneri (Roth.); the pyralid, Cryptoblabes gnidiella Millière, and the cosmopterigid, Pyroderces simplex Walsingham, were recorded as major pest species infesting sorghum panicles in Sohag Governorate. The dipteran parasitoid species, Nemorilla floralis (Fallen) (Tachinidae) emerged from the pupae of the E. gayneri and C. gnidiella, while the hymenopteran parasitoid, Brachymeria aegyptiaca (Chalcididae) was obtained from the pupae of all the studied microlepidopteran pests. Spiders, coccinellids, and Orius spp. were the dominant predators collected form panicles. Post-harvest, larvae, and pupae of lepidopteran pests, especially P. simplex recorded (147, 96, and 79 larvae) and (47, 30, and 73 pupae)/10 panicles in 2016, 2017, and 2018 seasons, respectively.


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