The pest status of insects in agricultural settings is human-defined based on behaviors that may negatively impact the yield of susceptible crops. As such, both the insect behavior and the affected crop play a part in determining pest status. One helpful means of understanding pest status involves using pest injury guilds, which distinguish different pest groups based on similar kinds of injury to comparable plant tissues. Pest injury guilds defined in the literature are reviewed and then applied to agriculturally significant Lepidoptera. More specialized Lepidoptera behaviors which are economically relevant, such as leaf-rolling or stem-boring, are examined within their respective injury guilds. In this review, fruit-piercing moths are discussed within the context of pest Lepidoptera behaviors and are highlighted due to their unique means of causing economic damage. Unlike other Lepidoptera in agricultural settings, fruit-piercing moths are harmful as adults rather than larvae, and directly injure fruits using a specially adapted proboscis.The ecology and systematics of fruitpiercing moths, as well as current control options, are also discussed.

Dermacentor variabilis Say is a tick species widely distributed in North America, where it is a common pest, and acts as vector for many tick-borne pathogens that affect both humans and livestock. In the United States, D. variabilis has a discontinuous geographic distribution. It is present eastwards of a line drawn from Montana to southernTexas, and a few disjoint populations western of the Rockies and in the intermountain region. It has been hypothesized that both groups may correspond to different species.The aim of this study was to investigate the population genetic structure of, and potential speciation within, D. variabilis.To do this, we generated a new data set based on nuclear markers (SNPs) discovered through next-generation sequencing.The results showed moderate population structure and supported the occurrence of gene flow between some genetic clusters. Maximum parsimony phylogenetic reconstruction showed a divergent monophyletic western clade and a generally eastern clade. Overall, the nuclear data set analyzed herein is congruent with previous findings based on mitochondrial markers, although it led to a higher level of resolution within the eastern clade. Additional lines of evidence are needed to determine whether eastern and western populations correspond to different species.

Heliothine eggs are commonly found on agricultural commodities and ornamental plants transported through domestic and international commerce. Tobacco budworm [Chloridea (Heliothis) virescens (F.)], Chloridea subflexa (Guenée), and the corn earworm [Helicoverpa zea (Boddie)] are indigenous pests of the American continent. Interceptions of the Old World bollworm [Helicoverpa armigera (Hübner)] at various ports of entry into the United States have been detected due to the invasion of this pest in South America, adding to the complexity and importance of decision making at plant inspection stations. The ability to distinguish the eggs of C. virescens from C. subflexa and Helicoverpa species is a critical component for conducting risk assessments by quarantine authorities, taxonomists, and crop consultants. We developed a simple, rapid (∼60 min), inexpensive ($0.06 per sample), and accurate (100% reliability) technique to distinguish C. virescens eggs from the possibility of being H. armigera based on the presence, number, and/or size of aeropyle holes on the primary ribs of eggs, near the micropylar rosette. In this location, aeropyles were easily visible at 40× magnification in 213 fresh and ethanol-preserved C. virescens eggs once treated with Hoyer's solution. A small number of C. subflexa had one or two aeropyles on a few of the primary ribs, whereas no aeropyles were found on 411 H. zea and 269 H. armigera eggs analyzed using optical, electron, and confocal microscopy. We conclude that in most cases multiple aeropyle holes positively identify H. virescens eggs from H. zea or H. armigera, and C. subflexa.This technique potentially will reduce the number of specimens that need to be sent for molecular identification thereby saving program time and resources.

Bark beetles have been recognized as the main insects that threaten forests worldwide. Several years of research related to evaluating the potential establishment of beetles have yielded widespread recognition of the usefulness of cluster analysis or species distribution models (SDMs) in predicting which species present a high risk of invasion. It is necessary to integrate current practices to quantitatively estimate the risk of establishment.This article analyzes global occurrence data of bark beetles using ‘SOM (self-organizing mapping) + MaxEnt’ to generate the list of high-risk species based on an SOM index and ranges of suitable distribution. All selected countries were clustered into nine clusters to discover which countries have similar bark beetles assemblages. A list of species considering potential threats that were absent from some countries was generated, and Hylurgus ligniperda and Scolytus multistriatus have a relatively high risk of establishment in China. Moreover, MaxEnt were used to analyze the potential geographic areas that species may be invaded. The results indicated that suitable regions of H. ligniperda are distributed in North America, Europe, the Middle East, Central Asia, and the southwest part of China. In addition, S. multistriatus has limited distribution on the Chinese mainland.The integration of SOM and MaxEnt provides a valuable reference for identifying potentially threatening invaders, and assessing the establishment risk for biological invasion, which provide the basis for forest management measures.

Historically, the South American locust, Schistocerca cancellata (Serville, 1838), has been considered the most serious agricultural pest in Argentina. An outbreak of a magnitude not recorded since 1954 started in 2015 through 2017 in northern Argentina and neighboring Paraguay and Bolivia. Schistocerca cancellata is widely considered as a true locust, with pronounced locust phase polyphenism, although the expression of its phenotypic plasticity has never been quantitatively tested under different density conditions. In this study, we explicitly quantified density-dependent reaction norms in behavior, coloration, and morphology in last instar nymphs of S. cancellata under isolated and crowded conditions. We also quantified density-dependent plasticity in adults (size) and in some life history traits. Our results showed that crowded nymphs were significantly more active and more attracted to congeners than isolated nymphs, and developed a much higher percentage of black pattern color. We also found that density had strong effects on body size and there was a sex-dependent pattern in both nymphs and adults, revealing that differences in size between males and females were less pronounced in crowded locusts. We have recorded for the isolated nymphs the presence of about 50% more hairs in the hind femora than in crowded nymphs. Finally, the mean duration of each nymphal instar and adult stage was significantly longer in isolated individuals. We have found strong resemblance with the desert locust, S. gregaria (Forskål, 1775) in several traits, and we conclude that S. cancellata exhibits an extreme form of density-dependent phenotypic plasticity in behavior, coloration, morphology, and life history traits.

Studying interactions between distantly related species is necessary to understand the complexity of food webs. Generalist predator interactions, such as intraguild predation (IGP) and competition, can alleviate predation pressure and weaken top–down control that predators have on lower trophic levels. Centipedes (Chilopoda) and carabid beetles (Coleoptera) are common deciduous forest floor generalist predators that may interact by competing for resources beneath rocks and logs on the forest floor, especially during dry periods when prey become confined to such microhabitats. We used laboratory and field studies to determine whether the carabid beetle, Pterostichus stygicus (Say), and the centipede, Scolopocryptops sexspinosus (Say) co-occur under artificial cover. Additionally, a laboratory mesocosm experiment was used to examine competitive interactions in intra- and interspecific trials. There was significant negative co-occurrence of beetles and centipedes beneath cover objects in the field and laboratory. Pairings of S. sexspinosus and P. stygicus within mesocosms resulted in high mortality of P. stygicus, and reciprocal but asymmetric IGP. Centipedes maintained weight within solitary, intra- and interspecific mesocosm treatments, however, beetles lost mass in all treatments. Scolopocryptops sexspinosus responded more favorably to intra- and interspecific competition than did P. stygicus. Analysis of the leaf litter mesofauna indicated that these predators consumed similar prey in laboratory mesocosms. Our results suggest that species with very different trophic morphology have the potential to compete for shared microhabitat and prey.

Heterogony was confirmed in the cynipid genus Cycloneuroterus Melika andTang in rearing experiments with DNA barcoding. These experiments involved Cycloneuroterus gilvusTang and Melika, which was previously only described from the sexual generation adult.The first rearing experiment was conducted using unidentified asexual generation females collected from Quercus gilva Blume, and gall formation by the sexual generation offspring was confirmed on folded or unfolded young leaves of Q. gilva.The second experiment was conducted using sexual generation males and females reared from the leaf galls collected from Q. gilva, and gall formation by the asexual generation offspring was observed on leaves of Q. gilva. Based on the morphological features of the sexual generation adults and galls, this species was identified as C. gilvus.The species identity of wasp specimens of sexual and asexual generations used in the rearing experiments was cross-checked using DNA barcoding with the partial sequences of the cytochrome c oxidase subunit I (COI) region (658 bp). The asexual generation adult and gall of C. gilvus are described based on these results.The importance of ‘closing the life cycle,’ in this case a demonstration of heterogony, in oak gall wasps (Cynipini) is discussed.

Koinobionts are parasitoids that allow their hosts to grow after infection, and they finally kill their host individuals at parasitoid-specific host stages. Since fatal accidents of host organisms directly result in the deaths of parasitizing koinobionts, a longer parasitization period in vulnerable hosts is likely to increase the mortality of the koinobionts. However, for hosts inhabiting concealed environments in their later developmental stages, koinobionts should begin parasitization in early-stage hosts to make use of the grown hosts. A koinobiont parasitoid, Aneurobracon philippinensis (Muesebeck), mainly uses a leaf-mining moth, Acrocercops transecta Meyrick (Lepidoptera: Gracillariidae) as a host. Due to the three-dimensional structure of the mines constructed by later instars of A. transecta, females of A. philippinensis seldomly oviposit into later instar hosts, whereas feeding on final instar hosts is essential for A. philippinensis larvae.This implies that oviposition targets in the wild are shifted to early instars, though the final instar is the ideal target to shorten the parasitization period. The dissection of wild host larvae demonstrated that no eggs were observed in the final instar, supporting the above expectation. Laboratory parasitization experiments revealed that A. philippinensis eggs hatched approximately 80 h after oviposition, and hatched larvae stayed in the first instar until the host larvae completed making cocoons.These results suggest that the first-instar period of the parasitoid larvae functions as an adjusting period to synchronize the parasitoid and host developmental stages and that koinobiosis plays an important role in utilizing the final instar of A. transecta as a resource.