Protective Geometry and Reproductive Anatomy as Candidate Determinants of Clutch Size Variation in Pentatomid Bugs.

AbstractMany animals lay their eggs in clusters. Eggs on the periphery of clusters can be at higher risk of mortality. We asked whether the most commonly occurring clutch sizes in pentatomid bugs could result from geometrical arrangements that maximize the proportion of eggs in the cluster's interior. Although the most common clutch sizes do not correspond with geometric optimality, stink bugs do tend to lay clusters of eggs in shapes that protect increasing proportions of their offspring as clutch sizes increase. We also considered whether ovariole number, an aspect of reproductive anatomy that may be a fixed trait across many pentatomids, could explain observed distributions of clutch sizes. The most common clutch sizes across many species correspond with multiples of ovariole number. However, there are species with the same number of ovarioles that lay clutches of widely varying size, among which multiples of ovariole number are not overrepresented. In pentatomid bugs, reproductive anatomy appears to be more important than egg mass geometry in determining clutch size uniformity. In addition, our analysis demonstrates that groups of animals with little variation in ovariole number may nonetheless lay a broad range of clutch shapes and sizes.

A new method to obtain isofemale lines for monitoring Chilo suppressalis resistance to Bt toxin.

Cost-effective Bt resistance monitoring programmes exist to manage insect resistance to Bt crops. F2 screening is widely used in detecting rare resistant alleles. One way to establish numerous isofemale lines for F2 bioassays is acquiring many field-trapped copulated females. However, it is difficult to obtain sufficient Chilo suppressalis isofemale lines because females have low mating rates and fecundity. We developed a new method to establish C. suppressalis isofemale lines with field-collected egg masses. No significant difference in detection ability was observed in the F2 screen between the old and new methods. Moreover, the new method is economical, convenient and efficient.

Observational evidence of egg guarding in wild European squid.

It is accepted that loliginids, like other squid, deposit their eggs in crevices on the seabed and then abandon them. In this work, we present observational evidence of egg guarding behavior in wild European squid, Loligo vulgaris. While monitoring a squid spawning crevice at night in Spain, a large mass of squid eggs was located and filmed 17 times during 42 days, until hatching. A male and a female of L. vulgaris were filmed in front of the crevice. The same male was filmed guarding the eggs on consecutive days. In the presence of the divers, male and female alternated their approaches to the crevice repeatedly touching and flushing the egg clusters. This guarding behavior differs from the reproductive habits assumed for the European squid and could represent the first evidence of egg guarding by a male in cephalopods.

An effective trap for spotted lanternfly egg masses.

Spotted lanternfly (SLF) (Lycorma delicatula (White)), an invasive planthopper discovered in Pennsylvania, USA in 2014, continues to spread and is now present in 14 states with substantial infestations present in seven states. Population projections using adult SLF trapping or visual counts are not reliable due to the transient, migratory behavior of the adults which make population forecasts difficult. Another approach to population monitoring is utilization of the stationary egg mass stage, but counting small cryptic egg masses throughout the canopy of large trees in dense woodlots is arduous and prone to error. After several field seasons testing various trapping configurations and materials, we have identified an efficient, simple, low-cost trap termed a 'lamp shade trap' that is attached to the lower trunk area of an SLF host tree. SLF females readily enter the trap and lay eggs on the thin, flexible trap surface. A vertical trap orientation was superior, and the most productive woodlots yielded an average of 47 and 54 egg masses per trap, and several traps had over 100 egg masses. There were 1,943 egg masses tallied from 105 traps placed at six locations in two states. Egg mass counts in the area above and below the traps and on nearby control trees yielded very few egg masses in comparison. Selection of trees 15 to 20 cm in diameter for trap placement is most efficient, yielding good egg mass abundance while minimizing the amount of trap material used. The lamp shade trap has potential as an effective tool to identify SLF in new areas, gauge SLF population levels in woodlots and can also be used to collect and monitor egg masses for research purposes.

Characterizing location of spotted lanternfly egg masses in wooded habitat during early invasion stages.

The spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae), is an invasive planthopper from Asia that is estimated to have spread 17 km/yr since it's initial detection in Pennsylvania in 2014. Lycorma delicatula is a pest to the agricultural and forestry industries in the Mid-Atlantic region of the United States, in part due to its highly polyphagous nature. Current detection relies on visual observations, unbaited traps, or eDNA surveillance in its primary hosts, including grape and hardwoods. These approaches narrow the surveillance area by concentrating on known host plants but could be further refined to narrow the search parameters from the 100+ known host plants. Because L. delicatula appears to have a strong population buildup in wooded areas, we evaluated the relationship between egg mass presence and habitat characteristics in wooded habitats adjacent to vineyards in New Jersey at six farms within the first two years of L. delicatula detection. Habitat characteristics included distance from wood edge, and presence of a critical host plant Ailanthus altissima, and presence of Vitis spp. within 4.5 m. We identified a significant relationship between egg mass presence and Vitis spp. with an 88% probability of finding an egg mass close to a wild grapevine, dropping to 9% where grapes were absent. During the early invasion stages when this research was conducted, a two-year delay from initial detection in wooded habitats to nymphal presence in the vineyard was observed.

Females of Halyomorpha halys (Hemiptera: Pentatomidae) Experience a Facultative Reproductive Diapause in Northern Greece.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is a native pest of East Asia that overwinters as an adult in natural and human-made structures. Adult emergence from overwintering sites starts in spring, whereas females produce offspring in early summer on host plants, where most feeding occurs. In this study, we investigated the reproductive physiology of overwintering females of H. halys in Northern Greece, by determining the duration of the preoviposition period and fecundity of individuals that were left to overwinter in natural conditions and were subsequently transferred to chambers with standard conditions monthly, from December 2020 to March 2021. According to our results, overwintering H. halys females do not initiate egg laying once they emerge from overwintering sites, but rather need some additional time to exit diapause and mature reproductively. The mean preoviposition period of overwintering females that were transferred from their overwintering sites to the chambers in December 2020 was 29.0 days, which was significantly longer by 8.3 days than that of females that overwintered until March 2021, and by 13.2 days than the control (26 °C, 60% RH and a 16:8 h light: dark photoperiod). No significant difference among the average number of eggs per egg mass laid by overwintering individuals brought in the chambers in different time intervals and the laboratory colony was observed. However, females that were left to overwinter until March laid a significantly higher number of eggs in total, compared to the ones whose overwintering was disrupted in February. Based on our findings, overwintering females of H. halys experience a facultative reproductive diapause in Northern Greece. Our study was the first to determine the occurrence of diapause of H. halys in N. Greece and our findings could be very valuable for assessing the damage of this pest to early-season crops and designing successful management practices.

Benthic litter in the continental slope of the Gulf of Naples (central-western Mediterranean Sea) hosts limited fouling communities but facilitates molluscan spawning.

Seafloor pollution by benthic litter is an emerging phenomenon, although debris colonization by biota remains largely unexplored. We characterized the litter of the continental slope (~400-600 m) of the Gulf of Naples (Mediterranean) and investigated its fouling biota through integrative taxonomic approaches. Plastic pieces (82 %) with land-based origin (96 %) and limited sizes (10-20 cm) were the items most commonly encountered, suggesting a transfer to deep waters through floating and sinking. The majority of the items were not fouled, and the debris hosted an impoverished biota, leading to hypothesize that benthic litter supports wide communities only in shallow waters. Higher colonization rates were observed for gastropod and cephalopod eggs with no preference for materials and sizes, suggesting that even small pieces of soft plastic provide a spawning habitat for molluscs and affect species' connectivity in the deep-sea ecosystem. Holistic approaches are necessary to evaluate interactions between litter and biota.

Implementing Mass Rearing of Trissolcus japonicus (Hymenoptera: Scelionidae) on Cold-Stored Host Eggs.

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), a pest of Asian origin, has been causing severe damage to Italian agriculture. The application of classical biological control by the release of Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), an exotic egg parasitoid, appears to be one promising solution. In Italy, releases of T. japonicus in the field were authorized in 2020. In this study, some parameters that could influence the rearing of T. japonicus in insectaries were investigated. A significantly higher production of progeny was observed on host eggs stored at 6 °C (86.5%) compared to -24 °C (48.8%) for up to two months prior to exposure to parasitism. There were no significant differences in progeny production from single females in a vial provided with only one egg mass (83.2%) or 10 females inside a cage with 6 egg masses (83.9%). The exposure of parasitoids to refrigerated (6 °C) egg masses of H. halys for 72 h led to a significantly higher production of progeny (62.1%) compared to shorter exposures for 48 (44.0%) or 24 h (37.1%). A decline in production of progeny by the same female was detected between the first (62.1%) and the second parasitization (41.3%). Adult parasitoids stored at 16 °C for up to 90 days had an 87.1% survival rate, but a significant decrease in progeny production was detected. These parameters could be adjusted when rearing T. japonicus for specific aims such as the production of individuals for field release or colony maintenance.

Azinphos-methyl causes in Planorbarius corneus toxic effects on reproduction, offspring survival and B-esterases depending on the exposure time.

This work aimed to study in the freshwater gastropod Planorbarius corneus the effects of acute (2 days) and subchronic (14 days) exposures to an environmental concentration of the organophosphate azinphos-methyl on different reproductive parameters, offspring survival and B-esterase activities in gonads and in the whole organism soft tissue. The acute exposure inhibited only carboxylesterase activity in both tissues while the subchronic exposure also inhibited cholinesterase activity, decreased the number of hatched-eggs and increased offspring lethality (92%). On the other hand, B-esterases in gonads were more effective biomarkers than B-esterases in the whole organism due their inhibition appeared earlier in time (cholinesterase activity) and their activity remained inhibited for a longer time (carboxylesterase activity) when recovery studies were performed. We concluded that B-esterases and reproductive parameters can be used as effect biomarkers of aquatic contamination with azinphos-methyl. Our studies showed that a 14 days exposure to an environmental concentration of azinphos-methyl produced severe signs of toxicity in adult organisms, egg masses and juveniles that could cause negative effects at the population level in contaminated environments.

Effects of copper on the survival, hatching, and reproduction of a pulmonate snail (Physa acuta).

Acute and chronic bioassays provide essential basis for establishment of environmental quality standards. The effects of Cu on a pulmonate snail, Physa acuta, were investigated at a number of sublethal and lethal endpoints. Cu exposure suppressed movement and triggered an escape response in P. acuta at low and high concentrations, respectively, exerting acute toxic effects on adult snails exposed to a 96 h LC50 of 23.8 µg L-1. Following 16 d exposure of Cu to the egg masses, successful hatching decreased with increasing Cu concentration. High Cu concentrations (12.5 and 25 µg L-1) resulted in inhibition of eye and shell development at the veliger stage, and a deformed shell, abnormal eyes, and different morphological shapes with lesions and hemorrhages were observed after 9 days of exposure. A large number of eggs exposed to 2.5-25 µg L-1 Cu remained in the veliger and hippo stages for 2-7 days, with no further development. Results from reproduction tests showed that adult snails exposed to various Cu treatments produced more than three broods, with the total number of eggs ranging from 770 to 1,289, revealing little difference between the control and Cu-treated groups (p > 0.05). However, snails exposed to 12.5 and 25 µg L-1 Cu produced polynuclear eggs in one egg capsule. The hatching success rate and shell length of the filial generation were significantly reduced in a dose-dependent manner (p < 0.05). The shell length of newly hatched snails was shorter in the reproduction test than in the hatching test, indicating inherent Cu toxicity in the filial generation from the exposed parent strain. The present study provides essential data regarding Cu toxicity in pulmonate snail P. acuta.

Isolation, cloning, and characterization of a cuticle collagen gene, Mi-col-5, in Meloidogyne incognita.

Cuticle collagens form a major part of the nematode cuticle and are responsible for maintaining the overall shape of the animal and its protection from the external environment. Although substantial research on cuticle collagen genes has been carried out in Caenorhabditis elegans, their isolation and characterization in plant parasitic nematodes have been limited to a few genes only. In this study, a cuticle collagen gene, Mi-col-5, was isolated from root-knot nematode, Meloidogyne incognita. A partial segment of 402 bp was first cloned and analyzed on Gbrowse followed by subsequent cloning of the 1047 bp long full cDNA specifying the open reading frame. The deduced amino acid sequence showed 92% sequence identity with that of Mj-col-5. However, a transmembrane helix was predicted in Mi-col-5 which was not present in Mj-col-5. The conserved pattern of cysteine residues in Mi-col-5 suggested that it belonged to group 2 of nematode cuticle collagens but with a longer carboxy terminal region as was the case with Mj-col-5. Domain prediction revealed the presence of a nematode cuticle collagen N terminal domain and a pfam collagen domain along with collagen triple helix repeats. A phylogenetic tree based on the amino acid sequences showed evolutionary relationship of Mi-col-5 with cuticle collagens genes of other nematodes. 3D models for Mi-col-5 were predicted with the best confidence score of -2.78. Expression of Mi-col-5 transcript was found to be maximum in egg masses followed by adult females and J2s suggesting its role in the early stages of the development of the nematode during its life cycle.

Hatching Response of Meloidogyne incognita acrita to Electric Shock.

The influence of electric shock on hatch of Meloidogyne incognita acrita from egg masses taken from roots of 'Acala SJ-I' cotton (Gossypium hirsutum L.) was studied. Egg masses in tap water were individually placed between the tips of needle electrodes 1 mm apart and exposed to potentials of l, 10, 20, and 60 vdc/mm at 1, 1, 1, and 86 milliamperes dc, respectively, for periods of 2 and 60 seconds. Hatched larvae were counted at five-day intervals for 60 days. Of the eight treatment combinations used, six gave a greater egg hatch than the control. The largest hatch, 520 percent greater than the control, resulted from exposure to 1 vdc/mm for 60 seconds; 60 vdc/mm for 2 and 60 sec decreased egg hatch 11 and 94 percent of the untreated control. Hatched larvae from all treatments except the 60 vdc/mm, 60-second exposure were infective and reproduced on young cotton plants in a glasshouse.

On the occurrence of egg masses of the diamond-shaped squid Thysanoteuthis rhombus Troschel, 1857 in the subtropical eastern Atlantic (Canary Islands). A potential commercial species?

Data on opportunistic sightings of diamond-shaped squid Thysanoteuthis rhombus egg masses in the Canary Islands (Atlantic Ocean) are presented. A total of 16 egg masses of this species were recorded and photographed from 2000 to 2010 around the western islands of the archipelago (El Hierro, Tenerife and La Gomera). These data reveal the existence of an important spawning area for diamond-shaped squid around the Canary Islands, in subtropical east Atlantic waters. We provide preliminary data for the potential development of an artisanal fishery focused on this species, and a discussion on its potential impacts on the marine ecosystem.

Effects of varying concentrations of the crude aqueous and ethanolic extracts of Dalbergia sissoo plant parts on Biomphalaria pfeifferi egg masses.

This study evaluated, using replicated laboratory bioassays, the toxicities of the crude aqueous and ethanolic extracts of Dalbergia sissoo Roxb. 1832 (family Leguminosae) fruits, leaves, roots and stem bark against egg masses of Biomphalaria pfeifferi (Krauss, 1848), the snail intermediate host of Schistosoma mansoni (Sambon, 1907) in Nigeria. Viable 0-24 hr-old embryonated egg masses were separately exposed to five different concentrations (7.81-2000 mg/l) of extracts for 24 hrs, washed in dechlorinated tap water and incubated at room temperature for a maximum of 4 weeks. The LC(50) and LC(90) values of test extracts for egg masses were calculated by probit analysis. The activities of the tested extracts were concentration-dependent. However, only the ethanolic extract of the fruits demonstrated significant activity (24 hr-LC(90) value < 100 mg/l: 89.29 mg/l). Mortalities of eggs were manifested at the gastrula/exogastrula and or the prehatch snail stage of development. The percentage of dead embryos at the prehatch snail stage decreased while the deaths of embryos at the gastrula/exogastrula stage increased, with increasing concentration of extract. Lethality of the ethanolic extract of D. sissoo fruits to embryonated egg masses of B. pfeifferi is an added advantage to its potential development for use as a plant molluscicide, as the overall efficacy of a molluscicide is greatly enhanced if it also shows significant toxicity towards snail eggs.

Obtención de masas ovígeras del caracol lancetilla, Strombus pugilis (Mesogastropoda: Strombidae) en condiciones de laboratorio / Obtaining of egg masses of the snail, Strombus pugilis (Mesogastropoda: Strombidae) under laboratory conditions

The survival, reproduction and embryonic development of Strombus pugilis, were determined during a period of ten months under laboratory conditions. Seven progenitors were collected in Contoy Island, Quintana Roo, Mexico and later transferred to the laboratory, where they were placed in aquarium with 80 1 of sea water and fed with "pellets". A total of 30 egg masses were collected, one on September and the other on April. The estimated total length of one egg mass was 11.24 m; the mean number of embryos obtained per 2 cm was 264, obtaining an estimated total of 157 500 embryos in the egg mass. The means of the physical-chemical parameters during the study were: salinity 37.6 +/- 0.5% per hundred, pH 7.5 +/- 0.5 and temperature 28 +/- 0.2 degrees C. The maintenance and water recirculation system used to sustain the breading stock is excellent both for reproduction of the organism and for obtaining egg masses under controlled conditions.