Micronecta griseola Horvath, 1899 - a new species of the family Corixidae (Heteroptera) for the fauna of the Middle Urals

Micronecta (Micronecta) griseola Horvath, 1899 is a representative of water bugs of the family Corixidae. It is expanding its range eastwards according to our observations in Russia. In the last decade, the species has become more common in Western Siberia. The article presents the first records of M. griseola from the territory of the Middle Urals (Russia). The distribution of the species and the features of its biology are considered.

Water bugs (Hemipera: Heteroptera: Nepomorpha & Gerromorpha) of Chile: phylogenetic and biogeographic considerations, and a catalog of the fauna

The Chilean fauna of water bugs comprises seven species of semi-aquatic bugs (Heteroptera: Gerromorpha), representing five genera, three tribes, four subfamilies and four families; and 27 species and one subspecies of aquatic bugs (Heteroptera: Nepomorpha), representing four subgenera, eight genera, three tribes, seven subfamilies, and five families. We compare the fauna with neighboring countries and find that several otherwise widespread and abundant taxa are missing in Chile, but that Chepuvelia usingeri China, 1963 (Macroveliidae), Microvelia chilena Drake & Hussey, 1955 (Veliidae), Limnocoris dubiosus Montandon, 1898 (Naucoridae), Nerthra (Nerthra) parvula (Signoret, 1863), N. (N.) undosa Nieser & Chen, 1992, N. (Rhinodermacoris) praecipua Todd, 1957 (Gelastocoridae), and Sigara (Tropocorixa) termasensis (Hungerford, 1928a) (Corixidae) are endemic to the country. To this list, we add †Nerthra (Nerthra) subantarctica Faúndez & Ashworth, 2015, even though the species is only known from a subfossil. We can also inform that while water bugs are found in the archipelagoes of southern Chile, no species has been reported from the Juan Fernandez Islands, Easter Island and other off-shore islands. Several of the Chilean species are without any close extant relatives, such as C. usingeri and Aquarius chilensis (Berg, 1881) (Gerridae), or with relatives in Oceania (N. praecipua), suggesting that historical events such as dispersal and extinction have had a major influence on the composition of the Chilean fauna.

Alternative prey influence the predation of mosquito larvae by three water bug species (Heteroptera: Nepidae)

The indirect interactions among multiple prey sharing a common predator characterize apparent competition. In conservation biological control involving mosquitoes and controphic prey against generalist insect predators, apparent competition may be a crucial factor determining the extent of success. The possible influence of apparent competition on mosquito prey consumption by three water bugs (Heteroptera: Nepidae): Ranatra elongata, Ranatra filiformis, and Laccotrephes griseus was assessed under laboratory conditions. Tadpoles (Duttaphrynus melanostictus), chironomid larvae, snails (Racesina luteola) and fish fingerlings (Labeo rohita) were considered as alternative prey under two prey or multi prey conditions against instar IV larvae of Culex quinquefasciatus as target prey. Under two prey conditions all the predators exhibited a preference (significant Manly’s α) for mosquito larvae, against fish fingerlings by R. filiformis. In the presence of multiple prey, mosquito larvae were selected by the predators. Using the ratio of mosquito selectivity in two prey and multi-prey conditions as a measure of apparent competition, chironomid larvae had greatest effect in suppressing mosquito selectivity for R. elongata, and fish fingerlings for R. filiformis and L. griseus. It seems that the prey preference of R. elongata, R. filiformis and L. griseus may differentially evoke apparent competition among the prey. In the aquatic community where these predators and prey coexist, mosquito larvae may benefit from apparent competition that reduces their vulnerability to predators. The identity of the alternative prey appears to be an important factor for shielding the vulnerability of mosquito prey to the generalist insect predators.

Contributions to the knowledge of water bugs in Mindoro Island, Philippines, with a species checklist of Nepomorpha and Gerromorpha (Insecta, Hemiptera, Heteroptera)

This survey aims to provide an updated species checklist of aquatic and semi-aquatic bugs in the intra-Philippine biogeographic Region of Mindoro. An assessment survey of water bugs (Hemiptera, Heteroptera) was conducted mostly by manual collection in selected areas of Oriental Mindoro from 2017 to 2018, in which some of the collecting activities were undertaken by graduate students of Ateneo de Manila University. Twenty-nine aquatic and semi-aquatic heteropteran species were documented and some are known island-endemic species or subspecies, including Enithares martini mindoroensis Nieser & Zettel, 1999, Hydrotrephes stereoides mindoroensis Zettel, 2003, Aphelocheirus freitagi Zettel & Pangantihon, 2010, Rhagovelia mindoroensis Zettel, 1994, Rhagovelia raddai Zettel, 1994, Rhagovelia potamophila Zettel, 1996 and Strongylovelia mindoroensis Lansbury & Zettel, 1997, which were found in new areas in the Region. In addition, there are also new records for the Island that have already been documented in other parts of the Philippines, such as the Philippine-endemic Ochterus magnus Gapud & San Valentin, 1977 and Hebrus philippinus Zettel, 2006 and the widely-distributed backswimmers Anisops nigrolineatus Lundblad, 1933 and Anisops rhomboides Nieser & Chen, 1999. Several undescribed specimens and potentially new species are also discussed in this paper. Further surveys in the other parts of Mindoro and in the other regions of the Philippines, are encouraged to produce a comprehensive baseline data of heteropteran species richness in the country.

Toxic Effects of Fine Plant Powder Impregnated With Avermectins on Mosquito Larvae and Nontarget Aquatic Invertebrates

The toxic effects of an avermectin-impregnated fine plant powder (AIFP) against larval Aedes aegypti L. (Diptera: Culicidae), Culex modestus Ficalbi (Diptera: Culicidae), and Anopheles messeae Falleroni (Diptera: Culicidae), as well as selected nontarget aquatic invertebrates, were studied under laboratory conditions. The possibility of trophic transfer of avermectins (AVMs) through the food chain and their toxic effects on predaceous species fed AIFP-treated mosquito larvae was also evaluated. Among mosquitoes, Anopheles messeae were the most sensitive to AIFP, while Cx. modestus exhibited the least sensitivity to this formulation. Among nontarget aquatic invertebrates, the greatest toxicity of AIFP was observed for benthic species (larval Chironomus sp. Meigen (Diptera: Chironomidae), whereas predators (dragonflies, water beetles, and water bugs) exhibited the lowest AIFP sensitivity. AIFP sensitivity of the clam shrimp Lynceus brachyurus O. F. Muller (Diplostraca: Lynceidae), the phantom midge Chaoborus crystallinus De Geer (Diptera: Chaoboridae), and the mayfly Caenis robusta Eaton (Ephemeroptera: Caenidae) was intermediate and similar to the sensitivity of the mosquito Cx. modestus. However, these nontarget species were more resistant than An. messeae and Ae. aegypti. Solid-phase extraction of mosquito larvae treated with AIFP and subsequent high-performance liquid chromatography (HPLC) analysis of the extracts revealed an AVM concentration of up to 2.1 ± 0.3 μg/g. Feeding the creeping water bug Ilyocoris cimicoides L. (Hemiptera: Naucoridae) on the AIFP-treated mosquito larvae resulted in 51% mortality of the predaceous species. But no toxicity was observed for Aeshna mixta Latreille (Odonata: Aeshnidae) dragonfly larvae fed those mosquito larvae. The results of this work showed that this AVM formulation can be effective against mosquito larvae.

Insect evolution toward aquatic habitats; reassessment of antennal sensilla in the water bug families Ochteridae, Gelastocoridae and Aphelocheiridae (Hemiptera: Heteroptera: Nepomorpha)

The first comparative morphology study on antennal sensilla of Ochteridae, Gelastocoridae and Aphelocheiridae, carried out with the use of a scanning electron microscope, is provided. Our research hypothesis was: the antennal sensilla of the studied families reflect their different adaptations for use in aquatic habitats, while maintaining a common set of sensilla similar to other water bugs (Nepomorpha). Therefore, the number and placement of antennal sensilla of several species in the mentioned families were studied using scanning electron microscopy. Nine main types of mechano- chemo- and thermo-hygroreceptive sensilla were confirmed on their surface, including sensilla trichodea, chaetica, club-like, campaniformia, basiconica, coeloconica, plate-like, ampullacea and sensilla placodea multilobated. While seven of these were already documented in other species, two of them (sensilla plate-like and placodea multilobated) were yet to be documented on the antennae of Nepomorpha. All families display differences in the shape and length of antennae as well as among sensilla types. These findings support our hypothesis regarding differences in sensillar structures among families adapted differently to suitable niches. Differences between these families and previously studied nepomorphan taxa (Nepoidea) were also documented. However, the general set of sensilla observed on the antennae of the studied species is very similar to the one documented in Nepoidea. Therefore, we confirmed our assumptions regarding similarities in antennal sensilla between the studied families and other nepomorphan insects.