S P E C I A L I S S U E – I N S E C T- P L A N T I N T E R A C T I O N S : H O S T S E L E C T I O N , H E R B I V O R Y, A N D P L A N T R E S I S TA N C E
DOI: 10.1111/eea.12524
Insect-plant interactions: host selection, herbivory, and plant resistance – an introduction Peter A. Follett* USDA-ARS, U.S. Pacific Basin Agricultural Research Center, 64 Nowelo St., Hilo, HI 96720, USA
In nature, most plants are fed upon by insects. Some herbivorous insects are very particular in their choice of food plants, whereas others are more generalist feeders. Plants are not passive bystanders, however, as they have evolved resistance to most potential insect attackers. The world is mostly green. Domesticated crops are also inherently resistant to most insects (Painter, 1951), although we are sensitive to any insect damage that reduces yield, quality and profits to the farmer, and certain insects can indeed devastate their crop host leaving nothing to harvest. The ancestors of modern-day crop plants coevolved with insects and through natural selection accumulated many physical and chemical traits that formed a core defense against attackers (Pedigo, 1999). Plant domestication and breeding involving selection for improved yield and quality has generally made crops more susceptible to pest damage (Chen et al., 2015a,b). The 11 papers in this issue explore various aspects of plant insect interactions and current methods and technology for improving crop resistance, reflecting the current state of the art. Puncture resistance due to fruit hardness can provide protection from insect oviposition and can be related to maturity stage. In Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), infestation appears to vary depending on the physical properties of the fruit. Drosophila suzukii is notorious for its serrated ovipositor which allows it to oviposit in relatively hard unripe, undamaged fruit unlike most other Drosophila spp. which prefer soft rotting fruit. Lasa et al. (2017) demonstrate that D. suzukii readily attacks guava in the early ripe stage despite the high force required to penetrate the guava epidermis. Takahara & Takahashi (2017) explore associative learning in D. suzukii using artificial substrates with various colors and firmness. Insect learning as it applies to host plant selection and the role of olfactory and visual cues is a fertile area for further research (Bernays & Chapman, 1994) i.e., can insects learn to associate visual and/or olfactory cues with host suitability?
*Correspondence: E-mail:
[email protected]
Thrips feeding (Thysanoptera: Thripidae) can cause stunted growth and delayed maturity in cotton and peanut, and thrips may transmit Tomato spotted wilt virus to peanut. Knight et al. (2017) examine whether conservation tillage using cover crops and reflective particle films may provide protection against thrips. Physical and chemical traits of cotton such as dense leaf hairs and gossypol may negatively affect thrips in cotton. The pre-adapted traits providing protection from insect pests still exist in the plant genome and finding and exploiting these traits forms the basis of host plant resistance. Miyazaki et al. (2017) have been studying thrips abundance and damage in a range of diploid Gossypium genotypes that vary in leaf hairiness, hardness, and shape to better understand the basis for their resistance to herbivory by thrips. Plant breeders may consider effects on yield without studying potential pleiotropic effects of resistance traits on flowering, pollination, and pollinators. Through the use of fig plant hybrids Ghana et al. (2017) show the importance of timing of stigma growth to pollinator [Kradibia spp. (Hymenoptera: Agaonidae)] attraction and success. Modern advances in genetic engineering and genomics have opened up unlimited possibilities for inserting specific traits for host plant resistance into crops and for teasing apart complex host plant resistant traits (Gordon & Waterhouse, 2007; Prado et al., 2014). Widespread planting of transgenic crops, such as those expressing Bacillus thuringiensis Berliner (Bt) endotoxins, creates strong selection pressure on pest populations to overcome the resistance factor. Yang et al. (2017) are gathering data on performance of susceptible (SS) and heterozygote (RS) sugarcane borer larvae [Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae)] moving among multiple plant resistance types to determine the durability of seed mixes of Bt sugarcane. What we learn from studies of deployment strategies in Bt crops, such as seed mixtures, refuges, and expression level, can assist in improving the durability of other types of host plant resistance as well. Host plant resistance is a major tactic for managing brown planthopper, Nilaparvata lugens St al (Hemiptera: Delphacidae), in rice. Using marker-assisted selection,
© 2017 The Netherlands Entomological Society Entomologia Experimentalis et Applicata 162: 1–3, 2017
1
2 Follett
Shabanimofrad et al. (2017) are mapping quantitative trait loci for host selection in brown planthopper-resistant cultivars so that these complex resistance traits can be moved into susceptible cultivars. Advances in DNA-marker genotyping and high-throughput technology-assisted breeding will aid in the isolation of resistance genes through map-based cloning, allow comparative genomic studies between crops, and help characterize genotypes with novel resistance mechanisms. Host evasion is a type of ecological resistance that relies on environmental conditions more than genetics. Planting of early maturing varieties, reduced tillage practices, and harvest of fruit at a non-preferred stage are examples of ways to avoid pest damage. Joseph (2017) is studying the effects of planting date, temperature, and moisture on feeding injury by the collembolan Protaphorura fimata (Gisin) (Collembola: Onychiuridae), a serious pest of lettuce in coastal California, USA. Studies by Hanavan & Bosque-Perez (2017) with pea weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), in conventional and no-till peas suggest that lower weevil abundance in no-till treatments is due to reduced plant apparency and crop availability during the peak colonization period. Plant volatiles emitted in the air close to the plant surface may act as repellents for insects and affect host selection. Intercropping with highly aromatic plants may imitate this type of non-preference resistance and act as a deterrent to host-locating insects. Carvalho et al. (2017) demonstrate how intercropping with basil and coriander can help protect tomato from Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) whitefly attack and reduce herbivory. Induced resistance occurs when damaged plants become less preferred for oviposition or less suitable for insect development, and these effects may be related to pest density and other factors. Plant feedback and compensation are underappreciated processes that reduce the effects of herbivory. McNutt et al. (2017) demonstrate that reduced adult preference and larval performance in Leptinotarsa juncta (Germar) (Coleoptera: Chrysomelidae), a close relative of Colorado potato beetle, on damaged Solanum carolinense L. (Solanaceae) is related to larval density and elevated plant trypsin proteinase inhibitor expression. The mechanisms of host plant resistance traits can be broadly grouped as antixenosis (non-preference), antibiosis, and tolerance. The physiological basis for these traits is often not understood, and this is one reason host plant resistance is not pursued as a pest control tactic in many crops. Also, pesticides have been an inexpensive replacement for the natural plant defenses that have been lost (Eigenbrode & Trumble, 1994). For certain crops where
pesticides are not practical or cost effective such as cereals and grains host plant resistance is the primary tactic for pest control (Maxwell & Jennings, 1980). All things considered, plant resistance has many advantages as a component of integrated pest management systems including selectivity against the pest, durability, compatibility with other tactics, and environmental safety. Entomologia Experimentalis et Applicata publishes high quality papers that explore the physiological, ecological, and morphological inter-relationships between phytophagous insects and their crop and food plants, and welcomes your submissions in this dynamic area of research.
References Bernays EA & Chapman RF (1994) Host Plant Selection by Phytophagous Insects. Chapman and Hall, New York, NY, USA. Carvalho MG, Bortolotto OC & Ventura MU (2017) Aromatic plants affect the selection of host tomato plants by Bemisia tabaci biotype B. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12534. Chen YH, Gols R & Benrey B (2015a) Crop domestication and its impact on naturally selected trophic interactions. Annual Review of Entomology 60: 35–58. Chen YH, Gols R, Stratton CA, Brevik KA & Benrey B (2015b) Complex tritrophic interactions in response to crop domestication: predictions from the wild. Entomologia Experimentalis et Applicata 157: 40–59. Eigenbrode SD & Trumble JT (1994) Host plant resistance to insects in integrated pests management in vegetable crops. Journal of Agricultural Entomology 11: 201–224. Ghana S, Suleman N & Compton SG (2017) Style length variation in male and female figs: development, inheritance and control of pollinator oviposition. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12533. Gordon KHJ & Waterhouse PM (2007) RNAi for insect proof plants. Nature Biotechnology 25: 1231–1232. Hanavan RP & Bosque-Perez NA (2017) Influence of no-tillage practices and later planting date on the pea leaf weevil, Sitona lineatus, in pea, Pisum sativum. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12517. Joseph SV (2017) Influence of plant age, temperature, and moisture on Protaphorura fimata feeding injury on lettuce in the Salinas Valley of California, USA. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12518. Knight IA, Rains GC, Culbreath AK & Toews MD (2017) Thrips counts and disease incidence in response to reflective particle films and conservation tillage in cotton and peanut cropping systems. Entomologia Experimentalis et Applicata 162. doi:10. 1111/eea.12523. Lasa R, Tadeo E, Dinorın LA, Lima I & Williams T (2017) Fruit firmness, superficial damage, and location modulate infestation by Drosophila suzukii and Zaprionus indianus: the case of guava in Veracruz, Mexico. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12519.
Insect-plant interactions: an introduction 3
Maxwell FG & Jennings PR (1980) Breeding Plants Resistant to Insects. Wiley, New York, NY, USA. McNutt DW, Samuelson K & Underwood N (2017) Pathways for plant-mediated negative feedback to insect herbivores: accounting for non-linear effects of larval density on plant quality and quantity. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12515. Miyazaki J, Stiller WN & Wilson LJ (2017) Sources of plant resistance to thrips: a potential core component in cotton IPM. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea. 12501. Painter RH (1951) Insect Resistance in Crop Plants. MacMillan, New York, NY, USA. Pedigo LP (1999) Entomology and Pest Management, 3rd edn. Prentice Hall, Upper Saddle River, NJ, USA.
Prado JR, Segers G, Voelker T, Carson D, Dobert R et al. (2014) Genetically engineered crops: from idea to product. Annual Review of Plant Biology 65: 769–790. Shabanimofrad M, Rafii MY, Ashkani S, Hanafi MM, Adam NA et al. (2017) Mapping of QTLs conferring resistance in rice to brown planthopper, Nilaparvata lugens. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12520. Takahara B & Takahashi KH (2017) Associative learning of color and firmness of oviposition substrates in Drosophila suzukii. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12521. Yang G, Niu Y, Head GP, Price PA & Huang F (2017) Performance of Cry1Ab-susceptible and -heterozygous resistant populations of sugarcane borer in sequential feedings on non-Bt and Bt maize plant tissue. Entomologia Experimentalis et Applicata 162. doi:10.1111/eea.12502.
