Search Results (13)

An essential first step to implement a control strategy against herbivorous insects is the monitoring of their populations. The efficacy of pheromone-based traps in capturing herbivorous insects can be enhanced by adding adjuvants and using slow-release dispensers to ensure long-lasting attractiveness. Here, we present datasets from a two-year field monitoring campaign of the invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), using clear sticky traps baited with its aggregation pheromone and a synergist, tested towards different dispensers and adjuvants. Bycatch data for native stink bugs (all Hemiptera: Pentatomidae) and leaf-footed bugs (Hemiptera: Coreidae) are also presented. The R code provided was used to organize data and generate weekly captures or weekly density of both H. halys and non-target species. The information provided in this article may contribute to the optimization of pest control strategies in agriculture. Full article

The study of qualitative morphological variation is essential for taxonomists and professionals involved in the identification and diagnosis of species of agricultural importance. This becomes particularly critical when quarantine decisions depend on the accurate identification of species belonging to highly diverse genera, poorly reviewed taxonomic groups, or sets of morphologically similar species that lack comprehensive identification keys. Geometric morphometrics has proven to be a powerful tool for resolving taxonomic uncertainties and distinguishing economically significant pest insects, even in the absence of formal taxonomic keys. In this study, we applied geometric morphometrics to analyze pronotum shape variation across 11 species of the genus Acanthocephala, representing nearly half of the currently recognized diversity in the genus, including several species of quarantine relevance to the United States. Our results indicate that principal component analysis accounted for 67% of the total shape variation and identified shape patterns that are useful for distinguishing between several species. Discriminate analysis further supported the differentiation among species, with significant differences confirmed through Mahalanobis distances. Although some species exhibited morphological overlaps, particularly among closely related taxa, most comparisons yielded statistically significant results. These findings demonstrate that the shape of the pronotum is a reliable and informative characteristic for species delimitation within the Acanthocephala group. We propose the use of geometric morphometrics as a reproducible, cost-effective, and robust method for species-level identification in taxonomically complex groups, which has valuable applications in quarantine inspection, pest monitoring, and agricultural biosecurity. Full article

Tomato (Solanum lycopersicum L.) is one of the most preferred hosts of polyphagous stink bugs (Hemiptera: Pentatomidae) and leaf-footed bugs (Hemiptera: Coreidae). These hemipterans can infest tomato fruits at all stages of fruit ripening. However, it is unclear whether there is any feeding preference for these true bugs among different ripening stages of tomato (green, breaker, pink, and red stages). Feeding and behavioral assays were performed to determine the feeding preference and damage potential of two common stink bugs—the brown marmorated stink bug (Halyomorpha halys (Stål)) and the southern green stink bug (Nezara viridula L.)—and a leaf-footed bug (Leptoglossus zonatus (Dallas)) among the various ripening stages of tomato. The results indicated that green is the most preferred ripening stage for N. viridula and L. zonatus, while pink tomatoes were found to be a more preferred feeding site for H. halys. Fully ripe red tomatoes were found to be the least preferred feeding site for all three insects. The findings of this study will be useful for developing fruit damage symptom-based monitoring programs and establishing economic threshold levels for these pests in tomatoes, as well as informing harvesting regimes. Full article

The leaffooted bug, Leptoglossus phyllopus (L.) (Hemiptera: Coreidae), probes and feeds on tissues of many plant species, including developing cotton bolls, causing seed damage and abscission. Insecticides are the primary tool for managing leaffooted bugs, but concerns about resistance and environmental harm highlight the need for alternative management strategies. One promising approach is using semiochemicals, such as plant- and insect-produced volatile organic compounds (VOCs), to trap or repel pests. Insect herbivores often use plant-produced VOCs to select suitable host plants for feeding and oviposition. Field observations of abundant adult leaffooted bugs on cotton bolls suggest that bugs aggregate at feeding sites. The goal of this study was to characterize VOCs from developing cotton bolls with and without leaffooted bug herbivory and evaluate how these VOCs affect adult bug foraging behavior. A portable dynamic headspace sampling method was used to collect VOCs from developing cotton bolls in the field, and VOC samples were analyzed using gas chromatography–mass spectrometry. Leaffooted bug herbivory induced volatile emissions from cotton bolls, with significant increases in the emissions of six compounds (benzaldehyde, α-pinene, β-pinene, β-myrcene, p-xylene, and (E)-β-caryophyllene). Dual-choice olfactometer assays revealed that adult leaffooted bugs were attracted to VOCs from damaged cotton bolls, as well as being attracted to synthetic benzaldehyde or α-pinene individually. In contrast, leaffooted bugs were repelled by the combination of synthetic benzaldehyde and α-pinene. These findings suggest that VOCs from cotton bolls are attractive to leaffooted bugs and could contribute to the development of attractive lures for integrated pest management. Full article

Trichopoda pennipes is a tachinid parasitoid of several significant heteropteran agricultural pests, including the southern green stink bug, Nezara viridula, and leaf-footed bug, Leptoglossus phyllopus. To be used successfully as a biological control agent, the fly must selectively parasitize the target host species. Differences in the host preference of T. pennipes were assessed by assembling the nuclear and mitochondrial genomes of 38 flies reared from field-collected N. viridula and L. phyllopus. High-quality de novo draft genomes of T. pennipes were assembled using long-read sequencing. The assembly totaled 672 MB distributed among 561 contigs, having an N50 of 11.9 MB and a GC of 31.7%, with the longest contig at 28 MB. The genome was assessed for completeness using BUSCO in the Insecta dataset, resulting in a score of 99.4%, and 97.4% of the genes were single copy-loci. The mitochondrial genomes of the 38 T. pennipes flies were sequenced and compared to identify possible host-determined sibling species. The assembled circular genomes ranged from 15,345 bp to 16,390 bp and encode 22 tRNAs, two rRNAs, and 13 protein-coding genes (PCGs). There were no differences in the architecture of these genomes. Phylogenetic analyses using sequence information from 13 PCGs and the two rRNAs individually or as a combined dataset resolved the parasitoids into two distinct lineages: T. pennipes that parasitized both N. viridula and L. phyllopus, and others that parasitized only L. phyllopus. Full article

A detailed description of the labial sensory organs of Leptoglossus occidentalis Heidemann, 1910 and L. zonatus (Dallas, 1852) (Hemiptera: Heteroptera: Coreidae) is presented. The detailed morphology, location, and distribution of different sensilla types on mouthparts were investigated and shown in micrographs taken with a scanning electron microscope. Nine types of aporous sensilla, and three uniporous sensilla were found. The possible functions of these sensilla as well as similarities and differences between the mouthparts of Leptoglossus and those of other terrestrial Heteroptera are discussed. The tip of the labium constitutes a functional “touch and taste area”, combining the chemosensitivity of uniporous sensilla P1–P3 and the mechanoreceptivity of A8 and A9 hair-like sensilla. A set of two cone-like chemosensilla types (9 + 2) was found on each lateral lobe of the labial tip. Literature analysis showed that such a set of cone-like sensory organs on the labial tip may be common in terrestrial Heteroptera. This observation confirms that the number and arrangement of sensilla is conservative and can be important in diagnosing taxa at various levels and in phylogenetic studies based on morphology. Full article

The leaffooted plant bug, Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae) is polyphagous and widely distributed in the Western Hemisphere. Although it has been recorded in California since around 1900, it has become a more common pest in almonds in the last decade. Other studies have shown that an established insect can become a pest when a new genotype is introduced. This study investigated the distribution of two lineages (strains) of L. zonatus in the Western Hemisphere. Specimens from the Leptoglossus collection in the national insect collection in Mexico were used to extract DNA and sequence the mitochondrial DNA cytochrome oxidase I (mtDNA COI) gene, for use in population genetic and phylogenetic analyses. New sequences from Mexico, Central and South America were combined with those available in GenBank, from California and Brazil. Two lineages (strains) of L. zonatus were uncovered. One lineage occurs in California, Mexico and Ecuador. The second lineage is more widespread and found in California, Mexico, Guatemala, Nicaragua, Bolivia and Brazil. The haplotype number and diversity, and nucleotide diversity, were found for samples from California, Mexico, and Brazil, for the two lineages, and for all 118 sequences combined. All sequences combined produced five haplotypes, and a haplotype diversity of 0.54. California and Brazil had 3 haplotypes each, with one haplotype shared (5 total). Haplotype diversity in California and in Brazil were 0.526 and 0.505, respectively. A haplotype network found that one haplotype was most abundant and widespread. The small number of haplotypes, a range expansion, and economic pest status of L. zonatus in California, all contribute to this insect being a potentially invasive insect pest. Full article

California currently produces about a quarter of the world’s pistachios. Pistachio nuts are susceptible to feeding by stink bugs and leaffooted bugs; therefore, the invasive presence of the highly polyphagous brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), is a concern to California pistachio growers. We aimed to assess the potential of H. halys to cause yield loss and nut damage to pistachios, which had not yet been assessed in the field. Over two years, terminal branch ends with pistachio clusters were enclosed in organdy cages from spring to fall and exposed to either H. halys, the native stink bug Chinavia hilaris Say (Hemiptera: Pentatomidae), or leaffooted bug Leptoglossus zonatus (Dallas) (Hemiptera: Coreidae), for 4–7-day feeding periods at different times of the season. We found that H. halys adults cause more epicarp lesions (external damage) when recorded at harvest time than the native species. They did not, however, cause more kernel necrosis (internal damage) than the two native species tested, which is a more relevant damage criterion for commercial production. There were no differences among insect species for any other recorded damage criteria. We conclude that H. halys could cause similar damage as the native species but note that H. halys population densities in California are still low and future damage levels will be dependent on this pest’s population density. Full article

The leaffooted bug, Leptoglossus zonatus (Heteroptera: Coreidae), has become a key pest of almonds, pistachios, and pomegranates in California. Adults and nymphs directly feed on nuts and fruits, which reduces crop yield and quality and can facilitate pathogen infections. Current monitoring strategies require growers to actively sample the tree canopy, with no economic thresholds being developed for this pest. To improve monitoring of L. zonatus, a three-year study was conducted to identify an optimal trap. A hanging cross-vane panel trap was identified as the best trap type in Year 1, and subsequent work in Years 1–3 focused on refining its use by modifying surface texture and color. Results indicated that coating trap surfaces with the lubricant fluon improved trap catching ability, and adults were most frequently recovered in yellow traps. A hanging cross-vane panel trap with these features could serve as the basis for the development of a new monitoring system for this pest in orchards, which could be improved further if semiochemical lures will be developed. Full article

In California’s San Joaquin Valley, feeding by the coreid pest, Leptoglossus zonatus, can cause considerable economic loss on almond and pistachio. This research was conducted to improve understanding of how winter temperatures affect mortality of overwintering adult L. zonatus and to develop a better understanding of the role pomegranate plays in the species’ life-history. We exposed 7410 field-collected adult L. zonatus to temperatures between −2 and −10 °C for a period of three, four, or six hours using insect incubators. At six hours of exposure, the, LD₅₀ and LD₉₅ occur at −5.8 and −9.7 °C, respectively. We classified L. zonatus as chill-intolerant. Temperatures cold enough to affect substantial mortality of overwintering L. zonatus rarely occur in the San Joaquin Valley. Whole aggregation destructive sampling from a pomegranate hedgerow in Fresno County was conducted to determine population dynamics. At late summer to early fall, aggregations consisted of >90% immature stages. By early to mid-winter, mean aggregation size decreased, consisting of only three to 12 late-instars and adults. During years one and two of the experiment, L. zonatus produced a generation on pomegranate, mostly between September and mid-November. Overwintering did not occur on pomegranate, rather the majority of adults emigrated to other overwintering locations by mid-winter. Full article

Leaffooted bugs (Leptoglossus spp; Hemiptera: Coreidae) are phytophagous insects native to the Western Hemisphere. In California, Leptoglossus clypealis and Leptoglossus zonatus are occasional pests on almonds. Early season feeding by L. clypealis and L. zonatus leads to almond drop, while late season feeding results in strikes on kernels, kernel necrosis, and shriveled kernels. A field cage study was conducted to assess feeding damage associated with L. clypealis and L. zonatus on four almond varieties, Nonpareil, Fritz, Monterey, and Carmel. The objectives were to determine whether leaffooted bugs caused significant almond drop, to pinpoint when the almond was vulnerable, and to determine the final damage at harvest. Branches with ~20 almonds were caged and used to compare almond drop and final damage in four treatments: (1) control branches, (2) mechanically punctured almonds, (3) adult Leptoglossus clypealis, and (4) adult Leptoglossus zonatus. Replicates were set up for eight weeks during two seasons. Early season feeding resulted in higher almond drop than late season, and L. zonatus resulted in greater drop than L. clypealis. The almond hull width of the four varieties in the study did not influence susceptibility to feeding damage. The final damage assessment at harvest found significant levels of kernel strikes, kernel necrosis, and shriveled almonds in bug feeding cages, with higher levels attributed to L. zonatus than L. clypealis. Further research is warranted to develop an Integrated Pest Management program with reduced risk controls for L. zonatus. Full article

Leptoglossus zonatus is a polyphagous pest found throughout much of the Western Hemisphere. In California, L. zonatus attacks almond, pistachio, pomegranate, and walnut crops, but the seasonal use of and economic damage to these crops varies. To better understand the seasonal changes of L. zonatus populations and to improve monitoring programs in California’s San Joaquin Valley, we caged overwintering adult males and females and then followed the resulting population dynamics over a one-year period. There were three generations over the one-year period, although eggs, nymphs, and adults overlapped among successive generations. From an initial 75 overwintering adult females, there were 1214 egg strands, 16,692 nymphs, and 4900 adults recorded during the one-year period. Depending on the generation, the number of nymphs per egg strand ranged from 11.3 to 14.3; the sex ratio was close to 1:1 with the exception of one female-biased cage; and nymph mortality ranged from 22.0% to 39.5%. Adult females isolated from each generation produced 2.4–5.1 egg strands per female that totaled 41.7–61.7 eggs per female with a 67.1–86.8% successful hatch rate. We find that the adult is the overwintering stage, as more adults (without food provisions) survived the winter compared to medium-sized or large-sized nymphs provided with both food and water. The results are discussed with respect to the development of L. zonatus control and monitoring programs for California’s multi-billion-dollar (US) nut crops. Full article

The leaf-footed bug Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae) is an important pest in the Americas. However, no preference of colors, sexual behavior nor aggregation pheromone has been reported, which can be used for detection, monitoring, and control purposes. In the laboratory we tested the attractiveness of white, violet, blue, green, yellow, and orange color to nymphs and adults (mated and unmated) and found that most adults and nymphs were attracted to and remained longer on blue and green colored cards than the other colors tested. We found that couples may remain in copula ≈185 min and mate ≈20 times in a 60 d period with a similar number of matings during the scotophase and the photophase. Sexual behavior consists of six patterns: grooming, abdomen movement, antenna movement, antennation, mounting, and mating. In a Y-tube olfactometer, 80 and 62.5% of the adults tested were attracted to a hexane-extract of the volatiles released by 40 males and 40 females, respectively. This is the first report of the biological evidence of an aggregation pheromone in this bug. Full article