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Integrated Pest Management (IPM) has made significant strides as an ecological and sustainable approach to managing insect pests in agriculture. However, despite widespread promotion in textbooks and publications, the adoption of ‘green’ tactics – whether biological, physical, biotechnological, or agronomic – has not met expectations in practice. Why is the adoption so limited, even with numerous effective individual strategies available? This is a challenging question, but researchers have started to provide some insights. In 2015, a consortium of scientists from the European network ENDURE (www.endure-network.eu) proposed eight principles for IPM. A central point they emphasized is the need for IPM practitioners to embrace the inherent complexity of developing sustainable crop protection strategies. Notably, in 2017, awareness of these complexities led to the emergence of a new conceptual framework for a more holistic and modern IPM science. This framework aimed to optimize the synergy between different IPM tactics, moving towards a truly integrated approach in practice. More recently, it has been argued that the current pest management science often overlooks the complexities of farming systems, and it is not geared towards a whole-sale transformation or redesign of current-day farming systems. Through bibliometric analyses, the authors demonstrated that many studies are conducted under simplified conditions – primarily in laboratories – where pest management tactics are routinely viewed as single-factor solutions instead of being treated in integrated manner i.e., as per the very definition of IPM. The lack of studies under complex, “real-world” conditions e.g. semi-field or open-field experi-ments, hinders our understanding of how different IPM strategies interact – whether synergistically, antagonistically, or neutrally. As a result, the technological readiness level of these ‘green’ tactics remains low and actionable information is infrequently generated. This slows their adoption by stakeholders who must manage the inherent complexities of real-world agricultural systems. It is the time to return to the original intent of IPM – true integration – by prioritizing integrated studies that better reflect the complexity of field conditions and even involve farmers.

Plant-herbivore interactions dominate food web links in terrestrial settings, thereby shaping ecosystem structure and functioning. Within a given plant, both primary and secondary metabolites mediate the interplay between above- and below-ground herbivores. Here, we investigate how root feeding by larvae of the turnip moth Agrotis segetum (Lepidoptera: Noctuidae) affects development and feeding behavior of an above-ground sap-feeder i.e., the large cotton aphid Acyrthosiphon gossypii (Hemiptera: Aphididae) on cotton. We further draw upon transcriptomics, metabolomics and in-vitro bioassays to elucidate how plant metabolites mediate these interactions. Root feeding reduces A. gossypii adult survival and fecundity by 35.1%. Aphids on A. segetum-infested cotton spend 7% longer probing cells than on un-infested plants. Root and stem herbivory by A. segetum larvae alters gene transcripts and metabolites in leaves, inducing biosynthesis of three flavonoids i.e., dihydromyricetin, phloridzin and dihydroquercetin. In-vitro bioassays show that the latter two compounds markedly decrease A. gossypii adult survival and fecundity. Below-ground herbivory thus elicits biosynthesis and systemic translocation of phloridzin and dihydroquercetin, with antagonistic effects on above-ground sap-feeders. Our study sheds light on the underlying mechanisms of herbivore-triggered plant defenses in cotton and reveals the interplay between herbivore guilds across ecological realms. We discuss the implications of these findings for pest management.

Many lepidopteran species rely upon active flight to migrate over long distances, thus pursuing ephemeral resources, colonizing new habitats, or escaping adverse meteorological conditions. Though their biology and ecology are often well studied, there is only scant information on their wingbeat frequency (WBF), a key aerodynamic determinant of insect flight. In this study, we assessed interspecific and seasonal variability in WBF for 85 different migratory species of Lepidoptera (11 families) under the laboratory conditions of 25 ± 1°C and 75 ± 5% RH. WBF of migrant individuals ranged between 6.7 and 84.5 Hz and substantial interspecific differences were recorded, with members of the Bombycidae exhibiting the highest mean WBFs (i.e., 55.1 ± 1.0 Hz) and Saturniidae the lowest (8.5 ± 0.2 Hz). At a species level, seasonal variation was observed in WBF for Mythimna separata(Walker) (Lepidoptera: Noctuidae), Scotogramma trifoliiRottemberg (Lepidoptera: Noctuidae), and Helicoverpa armigera(Hübner) (Lepidoptera: Noctuidae). Our findings add to the scientific knowledge on flight biology of migratory insects, facilitate (automatic) monitoring and population forecasting, and can have broader implications for insect pest management or biodiversity conservation.

Yellow passionfruit (Passiflora edulis f. flavicarpa O. Deg.) is a tropical fruit crop that is meeting increasing demand both in local and international markets in South America. The lance fly, Dasiops inedulis (Diptera: Lonchaeidae), affects P. edulis floral buds and flowers, and is thought to cause important yield losses in this crop. In Colombia, D. inedulis are commonly controlled through calendar-based applications of chemically synthesized insecticides, and no scientific criteria exist to guide pest management. In the present study, we simulated D. inedulis injury to passionfruit plants, over the course of three production cycles. We assessed the effect of seven different categories of flower bud removal (from 0% to 79.9%) on passionfruit yield and fruit quality parameters. Removal rates above 20% caused a significant reduction in the number of flowers, while yield levels were lowest at 50–79.9% bud removal. With increasing rates of flower bud removal, we observed higher initial production of buds and lower levels of natural abortion of floral and fruiting structures. For the three consecutive harvests, maximum yield levels were 7.57 ± 5.51 kg (mean ± SD; with 0–9.9% damage), and minimum yield was 2.37 ± 2.15 kg (60–69.9% damage) per plant. For fruit quality parameters, D. inedulis injury did not affect fruit pulp weight or the content of soluble solids (Brix). Our work provides insights into the impact of D. inedulis on yellow passionfruit production, and constitutes a basis for future integrated pest management programs for this pest.

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is both heteroecious and holocyclic, seasonally alternating between buckthorn (Rhamnus spp.), (the primary, overwintering host) and soybean, Glycine max (L.) Merr. (the secondary host). Recently, a classical biological control program for this invasive pest has been implemented in North America using the Asian aphidiine braconid wasp Binodoxys communis Gahan. Two critical, related questions regarding the overwintering biology of B. communis are 1) does the parasitoid maintain fidelity to A. glycines throughout the aphid life cycle and follow it to its primary host; and, if it does, 2) is parasitoid migration facilitated by phoretic movement within buckthorn-specific winged aphids? In the laboratory, we compared B. communis parasitism on several different autumnal morphs of A. glycines: winged gynoparae (fall migrants) and their oviparous offspring on buckthorn, fourth-instar alatoid nymphs that would form either gynoparae or summer migrants on soybean, and third-instar gynoparous alatoid nymphs on soybean. We also introduced gynoparae and B. communis onto caged buckthorn plants in southeastern Minnesota to examine autumnal parasitism under natural conditions. In both the laboratory and field, parasitism rates of oviparae were much higher than those of gynoparae. In addition, B. communis rarely completed development on fourth-instar alatoid nymphs. Although wasps successfully developed on third-instar gynoparous nymphs, these hosts mummified before forming wings. These results suggest that although at least one buckthorn-specific morph of A. glycines seems suitable for B. communis parasitism, it is unlikely that alate-mediated dispersal of immature parasitoids is an adaptive strategy to locate Rhamnus in this species.

The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is one of the most important pests in tropical and subtropical agriculture and is a key pest in greenhouse production worldwide. Current management of B. tabaci relies upon frequent applications of insecticides. Insecticide use not only directly affects pest populations through acute toxicity but also has indirect (sublethal) effects on pest physiology or behavior. In this study, we described sublethal effects of imidacloprid on adult feeding, immature development, adult fecundity, and F1 development of B. tabaci. Honeydew excretion of adults feeding on leaves treated with LC20 and LC40 concentration was significantly lower than that on untreated leaf discs. Egg production of B. tabaci adults subject to LC20 and LC40 concentrations also was less than untreated individuals. Upon transfer to untreated leaves, honeydew excretion and egg production recovered well within 24 and 48 h, respectively. Exposure to LC20 and LC40 concentrations significantly affected developmental time of B. tabaci eggs and nymphs, whereas it did not affect adult molting rate. We did not find sublethal effects on longevity and fecundity of B. tabaci adults when exposed to LC20 and LC40 concentrations for 24 h, and on egg hatching rate, nymphal mortality, and molting rate of the subsequent F1 generation. Exposure to imidacloprid at LC40 concentration significantly decreased the number of females in the F1 generation. Imidacloprid negatively affects development and reproduction of exposed individuals, and sex ratio of subsequent (F1) generation of B. tabaci, which probably disrupts B. tabaci population dynamics, slows population increase, and reduces infestation levels. Therefore, it is necessary to consider potential impact from imidacloprid for integrated management of the pest.

The green lacewing Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) is a common natural enemy of various insect pests in China and is frequently employed for augmentation biological control. Adults of this species perform migration flights after emergence, the nature of which affects its value for biological control program. In this manuscript, we report characteristics of C. sinica migratory populations captured during 2008-2009 using a light trap at Beihuang Island (Bohai Gulf), 40-60 km from mainland China, and their relationships with flight performance. In total, 1,452 migratory C. sinica adults were caught for these 2 yr. Throughout the sampling period, migratory populations consisted of >50% female individuals, most of which were in preoviposition period and had low degrees of ovarian development. During autumn, most migratory females were unmated. C. sinica females began oviposition since 7 d after emergence. Flight mill tests showed that 5-d-old females in preoviposition period flew over the longest distance (i.e., 4.50 ± 1.31 km) over 8 h and mating status did not affect flight performance. For 3-d-old individuals, males flew over larger distances than females, and unmated individuals exhibited stronger flight capability than mated ones. Hence, gender, mating status, and age all determine C. sinica flight performance. Based upon those findings, we can indicate that C. sinica migratory populations appear adapted to long-distance flights. This research should help understand C. sinica population dynamics and aid its incorporation within integrated pest management (IPM) packages for several crops.

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a key insect pest of cotton in Xinjiang cotton-planting region of northwest China. In this region, cotton is grown on average ~1.65 million ha (1.53~1.80 million ha) annually in largely monoculture agricultural landscapes, similarly to cropping systems in the United States or Australia. Under such cropping regimes, naturally occurring refuges (with non-Bt crops) may be insufficient to prevent H. armigera resistance development to Bt toxins. Therefore, we assessed frequency of alleles conferring resistance to Cry1Ac toxin of F1 and F2 offspring of H. armigera isofemale lines from two distinct localities in the region during 2005-2009. More specifically, a total of 224 isofemale lines was collected from Korla County (˜70% Bt cotton adoption) and 402 lines from Shache County (˜5% Bt cotton planting). Subsequent offspring was screened on Cry1Ac artificial diet. From 2005 to 2009, resistance gene frequency in Korla fluctuated between 0.0000 and 0.0040, while being 0.0000-0.0008 in individuals collected from Shache, and there were no significant increases in both counties from 2005 to 2009. Relative average development rates (RADRs) of larvae in F1 tests showed significant increases from Korla, but not in Shache. RADR of F1 larvae is significantly correlated with RADR of F2 offspring, indicating genetic variation in response to toxin in field H. armigera population. Although the occurrence of Cry1Ac resistance alleles was low in Xinjiang cotton-planting region of China, particular attention should be given to H. armigera resistance development in Korla County.

Microplitis mediator Haliday (Hymenoptera: Braconidae) is an important larval endoparasitoid of various lepidopteran pests, including Helicoverpa armigera (Hübner). In China, H. armigera is a key pest of cotton and is currently the focus of several biological control efforts that use M. mediator as principal natural enemy of this pest. To improve the success of biological control efforts, behavioral studies are needed that shed light on the interaction between M. mediator and H. armigera. In this study, we determined M. mediator response to volatile compounds from undamaged, mechanically injured, or H. armigera--damaged plants and identified attractive volatiles. In Y-tube olfactometer assays, we found that mechanically damaged plants and/or plants treated with H. armigera oral secretions did not attract wasps. However, volatiles from H. armigera–damaged plants elicited a strong attraction of both M. mediator sexes. Headspace extracts from H. armigera–damaged cotton were analyzed by coupled gas chromatography–electroantennographic detection (GC-EAD), and a total of seven different compounds were found to elicit electroantennogram (EAG) responses, including an unknown compound. Six different EAD-active volatiles were identified from caterpillar-damaged cotton plants, of which 3, 7-dimethyl-1, 3, 6-octatriene and (Z)-3-hexenyl acetate were the principal compounds. Olfactometer assays indicated that individual synthetic compounds of 3, 7-dimethyl-1, 3, 6-octatriene, (Z)-3-hexenyl acetate, and nonanal were attractive to M. mediator. Field cage studies showed that parasitism of H. armigera larvae by M. mediator was higher on cotton plants to which 3,7-dimethyl-1,3, 6-octatriene was applied. Our results show that the combination of terpenoids and green leaf volatiles may not only facilitate host, mate, or food location but may also increase H. armigera parasitism by M. mediator.

In the north central United States, populations of the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, and natural enemies with soybean aphid abundance across Iowa, Michigan, Minnesota, and Wisconsin, representing the range of conditions where soybean aphid outbreaks have occurred since its introduction. We sampled soybean aphid and its natural enemies, quantified vegetation land cover and measured soybean nutrients (potassium [K] and nitrogen [N]) in 26 soybean sites in 2005 and 2006. Multiple regression models found that aphid abundance was negatively associated with leaf K content in 2005, whereas it was negatively associated with habitat diversity (Simpson’s index) and positively associated with leaf N content in 2006. These variables accounted for 25 and 27% of aphid variability in 2005 and 2006, respectively, suggesting that other sources of variability are also important. In addition, K content of soybean plants decreased with increasing prevalence of corn-soybean cropland in 2005, suggesting that landscapes that have a high intensification of agriculture (as indexed by increasing corn and soybean) are more likely to have higher aphid numbers. Soybean aphid natural enemies, 26 species of predators and parasitoids, was positively related to aphid abundance; however, enemy-to-aphid abundance ratios were inversely related to aphid density, suggesting that soybean aphids are able to escape control by resident natural enemies. Overall, soybean aphid abundance was most associated with soybean leaf chemistry and landscape heterogeneity. Agronomic options that can ameliorate K deficiency and maintaining heterogeneity in the landscape may reduce aphid risk.