Diversity of ants (Hymenoptera: Formicidae) in the University of Kerala Campus, Thiruvananthapuram, India

Survey conducted on the ant diversity in the Kerala University Campus revealed a total 64 species under six subfamilies. Species belonging to the Myrmicinae dominated (51.5%) followed by Formicinae (20.6%), Ponerinae (13.2%), Dolichoderinae (4.4%), Pseudomyrmicinae (4.4%) and Dorylinae (1.5%). Endemic species Camponotus invidus Forel, 1892 , Cardiocondyla parvinoda Forel, 1902, Carebara spinata Bharti & Kumar, 2013 and Tetramorium rossi (Bolton, 1976) were recorded in the campus. Anoplolepis gracilipes (Smith, 1857), Paratrechina longicornis (Latreille, 1802), Monomorium carbonarium Smith 1858, Solenopsis geminate (Fabricius, 1804), Strumigenys membranifera Emery, 1869, Tetramorium bicarinatum (Nylander, 1846) and Hypoponera ragusai (Emery, 1894) (introduced species) were found in the campus. The results showed that the campus is rich in ant diversity. The sites with human interference showed less diversity. A potential new species in the genus Lepisiota was recorded. Trichomyrmex abberans, Carebara spinata, Crematogaster anthracina, Crematogaster biroi and Nylanderia indica are new records.

Population dynamics and pathogens of the invasive yellow crazy ant (Anoplolepis gracilipes) in Arnhem Land, Australia

<p>Though many populations of introduced species have been observed to collapse, the reasons behind these declines are seldom investigated. Anoplolepis gracilipes is considered among one of the top six most economically and ecologically damaging invasive ant species in the world. However, introduced populations of A. gracilipes have been observed to decline. My overall aims in this thesis were to document A. gracilipes population declines, to investigate the possibility that pathogens were playing a role in the observed population declines, and to identify putative pathogens infecting A. gracilipes as potential candidates for biocontrol agents. I documented the observed A. gracilipes population declines that were the driving force for this project. I detailed large-scale reductions in the spatial extent of four populations with before and after survey data. I also presented data on three populations that were recorded as present, but disappeared before they could be spatially delimited. I speculated on the possible reasons for these declines and explained why I do not think other explanations are likely. I then investigated the hypothesis that a pathogen or parasite is affecting A. gracilipes queens in declining Arnhem Land populations. I did this in three ways: 1) based on preliminary findings, I looked at the effect of an artificial fungal infection on A. gracilipes reproduction. I compared reproductive output between control colonies and those treated with either a fungal entomopathogen (Metarhizium anisopliae) or fungicidal antibiotics. There was no correlation between either treatment and the number of eggs, larvae, pupae or males a colony produced after 70 days. I found queen number had no effect on colony reproductive output, suggesting that queens are able to adjust their egg-laying rate in the presence of other queens. I found no evidence that M. anisopliae affected reproductive output at the tested concentrations; 2) I explored the hypothesis that a pathogen that kills or affects the reproductive output of A. gracilipes queens is the mechanism or reason behind the population declines. I measured queen number per nest, egg-laying rate, fecundity and fat content and compared them between sites in different stages of decline or expansion (population types, consisting of low, medium and high-density populations). I discovered that 23% of queens had melanized nodules, a cellular immune response in insects, in their ovaries or fat bodies. The presence of nodules was correlated with a 22% decrease in the number of oocytes per ovary; however, nodule presence was not associated with population type, suggesting that though there are clearly pathogens or parasites capable of penetrating the cuticle of A. gracilipes, they are unlikely to be responsible for the observed population declines; 3) I compared microbial communities (bacteria and viruses) between queens from different population types. I found viral sequences that match to the Dicistroviridae family of viruses in low and medium-density populations. I found no differences in bacterial community structure between population types. The presence of sequences similar to the entomopathogens Rhabdochlamydia and Serratia marcescens, as well as the reproductive parasite Cardinium in A. gracilipes, deserves further investigation. Though introduced species’ populations have been observed to decline, this is one of the first studies to quantitatively examine, document, and investigate a mechanism behind such a decline. Understanding the mechanisms by which an invader declines may have important implications for invasive ant management worldwide.</p>

Population dynamics and pathogens of the invasive yellow crazy ant (Anoplolepis gracilipes) in Arnhem Land, Australia

<p>Though many populations of introduced species have been observed to collapse, the reasons behind these declines are seldom investigated. Anoplolepis gracilipes is considered among one of the top six most economically and ecologically damaging invasive ant species in the world. However, introduced populations of A. gracilipes have been observed to decline. My overall aims in this thesis were to document A. gracilipes population declines, to investigate the possibility that pathogens were playing a role in the observed population declines, and to identify putative pathogens infecting A. gracilipes as potential candidates for biocontrol agents. I documented the observed A. gracilipes population declines that were the driving force for this project. I detailed large-scale reductions in the spatial extent of four populations with before and after survey data. I also presented data on three populations that were recorded as present, but disappeared before they could be spatially delimited. I speculated on the possible reasons for these declines and explained why I do not think other explanations are likely. I then investigated the hypothesis that a pathogen or parasite is affecting A. gracilipes queens in declining Arnhem Land populations. I did this in three ways: 1) based on preliminary findings, I looked at the effect of an artificial fungal infection on A. gracilipes reproduction. I compared reproductive output between control colonies and those treated with either a fungal entomopathogen (Metarhizium anisopliae) or fungicidal antibiotics. There was no correlation between either treatment and the number of eggs, larvae, pupae or males a colony produced after 70 days. I found queen number had no effect on colony reproductive output, suggesting that queens are able to adjust their egg-laying rate in the presence of other queens. I found no evidence that M. anisopliae affected reproductive output at the tested concentrations; 2) I explored the hypothesis that a pathogen that kills or affects the reproductive output of A. gracilipes queens is the mechanism or reason behind the population declines. I measured queen number per nest, egg-laying rate, fecundity and fat content and compared them between sites in different stages of decline or expansion (population types, consisting of low, medium and high-density populations). I discovered that 23% of queens had melanized nodules, a cellular immune response in insects, in their ovaries or fat bodies. The presence of nodules was correlated with a 22% decrease in the number of oocytes per ovary; however, nodule presence was not associated with population type, suggesting that though there are clearly pathogens or parasites capable of penetrating the cuticle of A. gracilipes, they are unlikely to be responsible for the observed population declines; 3) I compared microbial communities (bacteria and viruses) between queens from different population types. I found viral sequences that match to the Dicistroviridae family of viruses in low and medium-density populations. I found no differences in bacterial community structure between population types. The presence of sequences similar to the entomopathogens Rhabdochlamydia and Serratia marcescens, as well as the reproductive parasite Cardinium in A. gracilipes, deserves further investigation. Though introduced species’ populations have been observed to decline, this is one of the first studies to quantitatively examine, document, and investigate a mechanism behind such a decline. Understanding the mechanisms by which an invader declines may have important implications for invasive ant management worldwide.</p>

Biology, Ecology, and Management of the Invasive Longlegged Ant, Anoplolepis gracilipes

The longlegged ant ( Anoplolepis gracilipes) is one of the most damaging invasive tramp ants globally. It is generally found between latitudes 27°N and 27°S in Asia, although it has been introduced to other continents. Its native range remains debatable, but it is believed to be in Southeast Asia. Anoplolepis gracilipes invasion has many serious ecological consequences, especially for native invertebrate, vertebrate, and plant communities, altering ecosystem dynamics and functions. We examine and synthesize the literature about this species’ origin and distribution, impacts on biodiversity and ecosystems, biology and ecology, chemical control, and potential biocontrol agents. We highlight emerging research needs on the origin and invasion history of this species, its reproductive mode, its relationship with myrmecophiles, and its host–microbial interactions, and we discuss future research directions. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Keanekaragaman Semut Musuh Alami (Hymenoptera: Formicidae) pada Perkebunan Kelapa Sawit Rakyat di Kecamatan Timpeh Kabupaten Dharmasraya

Ekosistem perkebunan kelapa sawit terdiri dari berbagai jenis paku-pakuan, gulma, rerumputan dan serangga yang membentuk suatu ekosistem yang kompleks. Serangga dari golongan Formicidae merupakan aspek yang menarik untuk dikaji salah satunya yaitu semut. Pada ekosistem kelapa sawit, semut memiliki berbagai peran diantaranya sebagai penyerbuk, predator, pengurai dan herbivora. Penelitian ini dilaksanakan di perkebunan kelapa sawit rakyat di Nagari Panyubarangan dan Tabek, Kecamatan Timpeh, Kabupaten Dharmasraya, Sumatera Barat pada bulan September 2018 sampai Februari 2019. Penelitian ini bertujuan untuk mengetahui keanekaragaman semut pada ekosistem perkebunan kelapa sawit rakyat. Percobaan dilakukan dengan metode survei menggunakan metode Purposive Random Sampling. Pengambilan sampel menggunakan metode Hand Collecting, Bait Trap, dan Pitfall Trap. Identifikasi dilakukan di Laboratorium Taksonomi Hewan, Jurusan Biologi, Fakultas MIPA, Universitas Andalas, Padang. Analisis keanekaragaman menggunakan indeks Shannon-Wienner dan indeks kemerataan Simpson. Indeks keanekaragaman berkisar antara 1,83 sampai dengan 2,08. Total semut yang dikoleksi sebanyak 8.763 individu yang terdiri dari 14 genus, dan 29 spesies. Spesies yang paling dominan adalah Anoplolepis gracilipes diikuti Crematogaster borneensis dan Monomorium floricola dengan Indeks Nilai Penting yakni 0,57. Masing-masing spesies semut tersebut berperan sebagai predator beberapa hama kelapa sawit.

Parasitism disruption by ants of Anagyrus lopezi (Hymenoptera: Encyrtidae), parasitoid of cassava mealybug

Fanani MZ, Rauf A, Maryana N, Nurmansyah A, Hindayana D. 2020. Parasitism disruption by ants of Anagyrus lopezi (Hymenoptera: Encyrtidae), parasitoid of cassava mealybug. Biodiversitas 21: 2337-2343. Parasitoid, Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced into Indonesia in 2014 to control the invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). Among ants associated with honeydew-producing hemipterans, there are three common species in Indonesia i.e., Anoplolepis gracilipes (Smith), Dolichoderus thoracicus (Smith), and Oecophylla smaragdina (Fabricius) (Hymenoptera: Formicidae). The objective of this research was to investigate the relative influence of the three ant species on the parasitism of A. lopezi under laboratory conditions. Experiments were carried out by allowing a number of ants and parasitoids to forage on mealybugs-infested waterleaf (Talinum triangulare (Jaqc.) Willd.). The average time spent by individual parasitoid foraging was significantly longer (27.39 minutes) on ant-excluded plants compared to ant-attended plants (2.47- 4.68 minutes). Accordingly, parasitoid spent less time in finding hosts on ant-excluded plants, while spent a longer time in handling hosts. More oviposition activities by parasitoids on mealybug were occurred on ant-excluded plants compared to those on ant-attended plants. As a result, the percentage of parasitism and the number of wasps that emerged from the hosts on ant-excluded plants were almost 2 - 3 folds higher than those on ant-attended plants.