Biological control, a globally-important ecosystem service, can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in natural, urban and agricultural environments. Following (few) historic cases that led to sizeable environmental up-sets, the discipline of arthropod biological control has—over the past decades—evolved and matured. Now, by deliberately taking into account the ecological risks associated with the planned introduction of insect natural enemies, immense environmental and societal benefits can be gained. In this study, we document and analyze a successful case of biological control against the cassava mealybug, Phenacoccus manihoti (Hemiptera: Pseudococcidae) which invaded Southeast Asia in 2008, where it caused substantial crop losses and triggered two- to three-fold surges in agricultural commodity prices. In 2009, the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) was released in Thailand and subsequently introduced into neighboring Asian countries. Drawing upon continental-scale insect surveys, multi-year population studies and (field-level) experimental assays, we show how A. lopezi attained intermediate to high parasitism rates across diverse agro-ecological contexts. Driving mealybug populations below non-damaging levels over a broad geographical area, A. lopezi allowed yield recoveries up to 10.0 t/ha and provided biological control services worth several hundred dollars per ha (at local farm-gate prices) in Asia’s four-million ha cassava crop. Our work provides lessons to invasion science and crop protection worldwide. Furthermore, it accentuates the importance of scientifically-guided biological control for insect pest management, and highlights its potentially large socio-economic benefits to agricultural sustainability in the face of a debilitating invasive pest. In times of unrelenting insect invasions, surging pesticide use and accelerating biodiversity loss across the globe, this study demonstrates how biological control—as a pure public good endeavor—constitutes a powerful, cost-effective and environmentally-responsible solution for invasive species mitigation.

Abstract. Fanani Z. M., Rauf A, Maryana N, Nurmansyah A, Hindayana D. 2019. Geographic distribution of the invasive mealybug Phenacoccus manihoti and its introduced parasitoid Anagyrus lopezi in parts of Indonesia. Biodiversitas 20: 3751-3757. Cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is an invasive pest detected for the first time in Indonesia in 2010. An exotic parasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced and released in 2014 to control the pest. Study was conducted with the objective to determine the geographic distribution of P. manihoti and spread of A. lopezi. Field surveys were conducted on cassava fields in various locations in Lampung, Java, and Nusa Tenggara. Our studies showed that P. manihoti was found to be widely distributed in Lampung, Banten, West Java, Central Java, East Java, West Nusa Tenggara and East Nusa Tenggara. In each location visited, symptoms of P. manihoti infestation as indicated by internode distortion and bunchy top were prominent. Three years following release, parasitoid A. lopezi has established and spread into several cassava growing areas, except East Nusa Tenggara. Parasitism rates varied from 1.50% in West Nusa Tenggara up to 59.18% in East Java. Logistic regression revealed that probability of severe damage by the cassava mealybug was significantly (P<0.05) increased with the increasing abundance of ants.

Abstract. 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.

Biological control constitutes one of the world’s prime ecosystems services, and can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in both natural and agricultural environments. Following (very few) widely-documented historic cases that led to sizeable environmental up-sets, the discipline of insect biological control has -over the past three decades- gone through much-needed reform. Now, by deliberately taking into account the ecological risks associated with insect biological control, immense environmental and societal benefits can be gained. In this study, we document and analyze a rare, successful case of biological control against the invasive mealybug, Phenacoccus manihoti (Hemiptera: Pseudococcidae) which invaded Southeast Asia in 2008, where it caused substantial crop losses and triggered 2- to 3-fold surges in agricultural commodity prices. In 2009, the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) was released in Thailand and subsequently introduced into neighboring Asian countries. Drawing upon continental-scale insect surveys, multi-year population studies and (field-level) experimental assays, we show how A. lopezi attained intermediate to high parasitism rates across diverse agro-ecological contexts. Driving mealybug populations below non-damaging levels at a continental scale, A. lopezi allowed yield recoveries up to 10.0 t/ha and provided biological control services worth several hundred dollars per ha (at local farm-gate prices) in Asia’s 4-million ha cassava crop. Our work provides lessons to invasion science and crop protection worldwide, heralds a new era for insect biological control, and highlights its potentially large socio-economic benefits to agricultural sustainability in the face of a debilitating invasive pest. In times of unrelenting insect invasions, surging pesticide use and accelerating (invertebrate) biodiversity loss across the globe, this study unequivocally demonstrates how biological control – as a pure public good – constitutes a powerful, cost-effective and environmentally-responsible solution for invasive species mitigation.

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Abstract. Fanani MZ, Rauf A, Maryana N, Nurmansyah A, Hindayana D. 2020. Parasitism of cassava mealybug by Anagyrus lopezi: Effects of varying host and parasitoid densities. Biodiversitas 21: 4973-4980. The solitary endoparasitoid Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced into Indonesia in 2014 to control the cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). The objectives of this study were to understand the influence of host and parasitoid densities on functional response and mutual interference of the parasitoid, by altering either the host or parasitoid density while keeping the other constant. The effects of host and parasitoid densities on parasitism, superparasitism, progeny production, and sex ratio were also assessed. Logistic regression was used to determine the shape of the functional response. Nonlinear least-squares regression was used to estimate the attack rate (a) and handling time (Th). Nicholson’s model and linear regression were used to determine per capita searching efficiency and interference coefficient, respectively. The logistic regression results suggested a Holling type II functional response to changing host densities, with an estimated attack rate (a) and handling time (Th) were 0.037 h-1 and 1.19 h, respectively. The estimated maximum number of mealybugs parasitized over 24-h period was 20.2 mealybugs. The wasp-mealybug ratio and offspring production increased significantly from 1:2 to 1:100 and from 1.35 to 10.45, respectively. However, the per capita number of parasitization decreased significantly from 14.20 to 4.37, with the increase in parasitoid density from 1 to 8. Searching efficiency of the parasitoid decreased significantly with increasing parasitoid density, with a mutual interference constant (m) of -0.52.

No abstract

Biological control constitutes one of the world’s prime ecosystems services, and can provide long-term and broad-scale suppression of invasive pests, weeds and pathogens in both natural and agricultural environments. Following (very few) widely-documented historic cases that led to sizeable environmental up-sets, the discipline of insect biological control has -over the past three decades- gone through much-needed reform. Now, by deliberately taking into account the ecological risks associated with insect biological control, immense environmental and societal benefits can be gained. In this study, we document and analyze a rare, successful case of biological control against the invasive mealybug, Phenacoccus manihoti (Hemiptera: Pseudococcidae) which invaded Southeast Asia in 2008, where it caused substantial crop losses and triggered 2- to 3-fold surges in agricultural commodity prices. In 2009, the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) was released in Thailand and subsequently introduced into neighboring Asian countries. Drawing upon continental-scale insect surveys, multi-year population studies and (field-level) experimental assays, we show how A. lopezi attained intermediate to high parasitism rates across diverse agro-ecological contexts. Driving mealybug populations below non-damaging levels at a continental scale, A. lopezi allowed yield recoveries up to 10.0 t/ha and provided biological control services worth several hundred dollars per ha (at local farm-gate prices) in Asia’s 4-million ha cassava crop. Our work provides lessons to invasion science and crop protection worldwide, heralds a new era for insect biological control, and highlights its potentially large socio-economic benefits to agricultural sustainability in the face of a debilitating invasive pest. In times of unrelenting insect invasions, surging pesticide use and accelerating (invertebrate) biodiversity loss across the globe, this study unequivocally demonstrates how biological control – as a pure public good – constitutes a powerful, cost-effective and environmentally-responsible solution for invasive species mitigation.