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Global biodiversity decline is continuing largely unabated. The International Union for Conservation of Nature (IUCN) Red List of Threatened Species (hereafter, Red List) provides us with the gold standard for assessments, but taxonomic coverage, especially for invertebrates and fungi, remains very low. Many players contribute to the Red List knowledge base, especially IUCN Red List partners, IUCN-led assessment projects, and the Specialist Groups and Red List Authorities (RLA) of the IUCN Species Survival Commission. However, it is vital that we develop the next generation of contributors and bring in new, diverse voices to build capacity and to sustain the huge assessment effort required to fill data gaps. Here, we discuss a recently established partner network to build additional capacity for species assessments, by linking academia directly into the assessment processes run by Specialist Groups and RLAs. We aim to increase Red List “literacy” amongst potential future conservationists and help students to increase publication output, form professional networks, and develop writing and research skills. Professors can build Red List learning into their teaching and offer Red Listing opportunities to students as assignments or research projects that directly contribute to the Red List. We discuss the opportunities presented by the approach, especially for underrepresented species groups, and the challenges that remain.

A newly discovered species of Masteria L. Koch, 1873 collected under rock debris near the entrance of Pelpel cave from Pangasinan, Luzon island, Philippines, Masteria urdujae sp. nov. is described. It is the first masteriine species described from Northern Luzon and the third for the country. M. urdujae has six eyes, typical of the genus. It is currently the smallest of the recorded Indomalayan masteriine species. Keywords: Masteria, Mygalomorphae, Pangasinan, Philippines, Taxonomy

Despite the fact that massive outbreaks of the coconut scale insect pest, Aspidiotus rigidus Reyne (Hemiptera: Diaspididae) are inflicting significant economic losses to the Philippines&rsquo, coconut industry, little is known about the population and dispersal history of this invasive pest in the country. Here, we examined the genetic diversity, structure and demographic history of A. rigidus sampled from localities with reported outbreaks from 2014 to 2017. We analyzed the genetic structure of the outbreak populations using mitochondrial COI and nuclear EF-1&alpha, markers. Both markers and all methods of population genetic structure analyses indicate clear differentiation among the A. rigidus populations separating the north from the southern regions of the Philippines. Very low or no genetic differentiation was observed within and amongst the populations per geographic region indicating two unrelated outbreak events of the pest originating from two genetically uniform populations isolated in each respective region. Historical data supports the resurgence of an established A. rigidus population in the south which could have been driven by sudden climatic changes or human-induced habitat imbalance. Our study provides valuable information on the genetic differentiation of the two A. rigidus groups that would be useful for developing and implementing biological control strategies against this pest in the Philippines.

Very little is known about the arthropods associated with the wild ancestors of agricultural crops. Given that wild relatives of crop plants are subjected to human pressures of habitat loss and transgene flow, baseline levels of arthropod biodiversity and community composition are urgently needed to detect declines associated with anthropogenic disturbance. Here, we sampled arthropod abundance and community composition on the wild ancestor of cultivated rice, Oryza rufipogon Griffiths, in the Mekong Delta of Vietnam to ask: 1) Do arthropods associated with O. rufipogon fluctuate temporally and spatially in terms of community composition, diversity, and abundance? 2) What is the abundance and diversity of lepidopteran and hemipteran species associated with O. rufipogon across sites and seasons? We found a total of 578 arthropod taxa, distributed across 178 families in 17 orders. Rarefied species richness and arthropod abundance did not vary across the sampled stands of O. rufipogon , but did vary across the years. Arthropod abundance and metrics dependent upon abundance generally declined over the observation period, suggesting that the sampling effects or other unobservable factors may have contributed to the decline in the arthropod community. Overall, predators dominated the community composition, followed by detritivores and herbivores. Predatory and herbivorous taxa were the most speciose guilds. We found 45 unique taxa of Lepidoptera, many of which were previously undescribed on rice. Given that wild relatives such as Oryza rufipogon support a diverse arthropod community, this study provides a baseline evaluation of the arthropod community in this important native habitat.

Insect pest management depends on simple, rapid, and reliable sampling methods that should also be standardized and optimized. We tested structured inventory, community characterization, and sampling optimization approaches on the invertebrate fauna of Philippine irrigated rice, undisrupted by pesticides, using seven field methods and species richness models. Canopy and floodwater invertebrates were intensively and repetitively sampled from 600 quadrats (∼0.1-m(2) planar area) over dry and wet cropping seasons in one field at the International Rice Research Institute in the Philippines. In the canopy, pooled counts from D-Vac and plant dissections (PD) on the same rice hills ("absolute methodology") were compared with three other methods (i.e., FARMCOP, Blower-Vac, sweep-net), while, in the floodwater, the area collector ("absolute methodology") was compared with three other methods (i.e., FARMCOP, Blower-Vac, strainer-net). Overall, 25 and 50% of the observed richness of canopy and floodwater taxa, respectively, were caught by all four methods. Estimated inventory completeness for the canopy and floodwater averaged 82 and 98%, respectively, after all methods were pooled. To maximize observed richness, optimization results for the canopy recommended allocating the highest sampling effort to D-Vac and PD, followed by the Blower-Vac, whereas the area collector should be assigned the highest sampling effort in the floodwater, followed by the strainer-net or Blower-Vac. Our results suggest that structured inventory and species richness models are useful tools for setting optimization criteria and stopping rules for sampling crop-invertebrate assemblages based on inventory completeness and for enabling more informative biodiversity comparisons.

ABSTBACT Although it is well established that biodiversity plays an important role in pest control, there is limited knowledge on how the origins of agriculture may shape arthropod biodiversity. Arthropod food webs likely have coevolved with wild crop relatives before domestication, but not all arthropod taxa may be able to inhabit cultivated habitats. We sampled wild and cultivated rice fields in the Mekong Delta of Vietnam to determine how season (dry versus wet) and rice cultivation influenced arthropod diversity and community composition. We found that cultivated rice fields supported ≈50% fewer taxa than wild rice fields, and that there were widespread losses in taxonomic richness within all of the major orders. Wild rice fields supported 173 unique taxa that were not found in any cultivated rice fields, whereas cultivated rice (Oryza sativa L.) supported only 23 unique taxa. Furthermore, wild and cultivated rice supported different arthropod communities. Predators and parasitoids were the most abundant in wild rice during the dry season. Herbivore densities were similar in wild and cultivated rice, but were reduced in wild rice (Oryza rugipogon L.) during the wet season. Neither season nor habitat influenced the densities of detritivores, but aquatic predators were more abundant during the dry season. This study provides empirical evidence that large-scale losses of species richness and changes in arthropod community structure are associated with the cultivation of domesticated rice.

Summary 1. Fallowing, a type of rotation where no crop is grown, deprives insect pests of food. In tropical irrigated rice, it is not known whether fallow periods deplete natural enemy populations and reduce their pest control effectiveness in post-fallow crops. We tested the null hypothesis that small-scale synchronous cropping (embedded in asynchronously planted rice landscapes) does not significantly increase pest densities during post-fallow periods in the presence of a large, diverse natural enemy complex undisrupted by insecticides. We tested this null hypothesis by comparing the invertebrate fauna before and after fallowing. 2. In six molluscicide-only fields at the International Rice Research Institute (IRRI) in southern Luzon and at Zaragoza in central Luzon, Philippines, canopy and floodwater invertebrates were vacuum-sampled over two cropping seasons, dry and wet. 3. Thirty-three of the ubiquitous common taxa dominated the samples in both seasons at each site. Most species were natural enemies of rice pests and recyclers of organic matter in the floodwater and waterlogged sediments; some were rice pests. 4. Fallowing depleted populations of more ubiquitous taxa at Zaragoza (four natural enemies, one detritivore) than at IRRI (one herbivore, one natural enemy). At both sites, only green leafhoppers, Nephotettix virescens and Nephotettix nigropictus, had consistently higher post-fallow densities than pre-fallow densities. 5. At both sites, fallowing did not affect rice-invertebrate faunas differently between seasons with regard to community structure, trajectories and accumulation rates of guild members. 6. Synthesis and applications. In tropical irrigated rice fields, small-scale synchronous fallowing combined with low-pesticide inputs and pest-resistant rice varieties did not induce pest outbreaks or notably diminish populations of natural enemies when embedded in asynchronous cropping on larger, regional scales. Our results suggest that small-scale synchronous fallowing, when embedded in asynchronously planted landscapes, does little harm to biological regulation of the invertebrate faunal community and may be adopted as part of integrated pest management when it serves other

The orb-web garden spider Argiope aemula (Walckenaer, 1841) is a sit-and-wait predator. It is argued that it can anticipate its future prey environment by detecting the presence of prey and adjusting their web building behavior accordingly. Therefore this study therefore investigates the influence of the different prey sizes and density of the capture area and mesh height of the webs constructed by the spider. In the laboratory, the spiders were given prey with different size and densities to determine their influence on the web architecture. Results show that spider individuals can increase or decrease the sizes of webs, capture area, and mesh height in response to prey size and density. Starved spiders constructed significantly larger webs than well-fed spiders. In the absence of potential prey, the spiders constructed larger capture area. In the presence of small prey, spiders significantly constructed very narrow- meshed webs or tightly spaced capture spirals than the presence of larger prey but larger than in no prey regime. Similarly, the food deprived spiders spun small-spaced mesh height than well-fed spiders. The results of the present study demonstrate that spiders can manipulate their web architecture in response to different prey sizes and food availability (densities).

Field data suggest that ants may be important predators of mantises which, in turn, may be important predators of jumping spiders (Salticidae). Using a tropical fauna from the Philippines as a case study, the reactions of mantises to ants, myrmecomorphic salticids (i.e. jumping spiders that resemble ants) and ordinary salticids (i.e. jumping spiders that do not resemble ants) were investigated in the laboratory. Three mantis species (Loxomantis sp., Orthodera sp., and Statilia sp.) were tested with ten ant species, five species of Myrmarachne (i.e. myrmecomorphic salticids), and 23 ordinary salticid species. Two categories of the myrmecomorphic salticids were recognized: (1) ‘typical Myrmarachne’ (four species with a strong resemblance to ants) and (2) Myrmarachne bakeri (a species with less strong resemblance to ants). Ants readily killed mantises in the laboratory, confirming that, for the mantises studied, ants are dangerous. In alternate-day testing, the mantises routinely preyed on the ordinary salticids, but avoided ants. The mantises reacted to myrmecomorphic salticids similarly to how they reacted to ants (i.e. myrmecomorphic salticids appear to be, for mantises, Batesian mimics of ants). Although myrmecomorphic salticids were rarely eaten, M. bakeri was eaten more often than typical Myrmarachne. Because the mantises had no prior experience with ants, ant mimics or ordinary salticids, our findings suggest that mantises have an innate aversion to attacking ants and that this aversion is generalized to myrmecomorphic salticids even in the absence of prior experience with ants. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 23–32.

The rice white stemborer (WSB) Scirpophaga innotata (Walker) supplanted the closely related rice yellow stemborer (YSB) S. incertulas (Walker) in irrigated, double-rice culture in both Koronadal, South Cotabato, Philippines and Java, Indonesia. In Java, WSB became a serious pest but not in Koronadal where damage levels remained unchanged. The species shift and subsequent outbreaks are seen as independent events. The former occurred just after the El Nino droughts in 1982 – 1983 which suggests that climatic factors triggered the demise of YSB which does not aestivate. A contributing factor may have also been the crop failures from pest outbreaks that occurred during the same period creating long fallows which would have allowed WSB larvae selectively to survive. WSB larvae have been known to diapause for up to 10 – 12 months and consequently is able to survive climatically driven long fallows. Diapause is terminated by rainfall >10 mm after larvae have rested for a minimum of 4 months. Supportive ...

Although the rice white stemborer (WSB) Scirpophaga innotata (Walker) has been an epidemic pest in other locations in the Philippines and Indonesia, its population has remained at chronic pest levels in Koronadal, southern Mindanao, Philippines. Field studies were undertaken to determine the role of egg parasitoids and general predators in suppressing WSB numbers. The results revealed greater mortality levels on WSB than in any other location where beneficials have been assessed. Four hymenopteran parasitoids (Tetrasticus schoenobii Ferriere [Eulophidae], Telenomus rowani (Gahan) [Scelionidae], Telenomus dignus (Gahan), and Trichogramma japonicum Ashmead [Trichogrammatidae]) combined to parasitise 65% of eggs in the second 1990 – 1991 rice crop. Multiple parasitism occurred in 61% of parasitised egg masses. Egg predation averaged 44% principally by the tettigoniids Conocephalus longipennis (de Haan) and C. maculatus (Leth.). Generalist predators steadily built up over the rice crop. A contributin...

Ants prey on salticids, and encounters with weaver ants (Oecophylla smaragdina(Fabri- cius 1775)) appear to be especially dangerous for many salticids. In the Philippines, Myrmarachne assimilis Banks 1930 is a salticid that mimics Oecophylla smaragdina. We tested for the abilities of four categories of salticids, plus M. assimilis, to survive in the proximity of weaver ants. The four categories were: (1) myrmecomorphic (ant-like species other than M. assimilis); (2) myrmecophagic (ant-eating species); (3) myrmecophilic (a species that is either myrmecophagic nor myrmecophagic, but is known to associate with ants) and (4) ordinary (species that are neither ant-like nor ant-eating, and are not known to associate with ants). The hypothesis investigated here is that M. assimilis has, compared with other salticids, es- pecially pronounced ability to survive in close proximity with this particular ant species. The individual salticids used in our experiments had not had previous contact with weaver ants or any other ants. When confined with groups of 10 weaver ants, the myrmecomorphic, myrmecophagic and myrmecophilic species survived significantly more often than ordinary salticids, but Myrmarachne assimilissurvived significantly more often than all other categories. When kept with groups of 20 ants, there was a proportional decrease in the number of salticids that survived within each salticid category. However, few salticids survived when confined with groups of 40 ants, regardless of category.

Cleora contiguata bigladiata is recollected from its type locality 48 years after its original description in 1953. Meanwhile, C. decisaria and C. determinata are recorded in Mt. Makiling for the first time. The latter species is also a new country record. These additional locality data are added to the updated checklist of Cleora from the Philippines.

Using a tropical fauna from the Philippines as a case study, ant‐salticid predator‐prey relationships were investigated. In the field, 41 observations of ant predation on salticids were made, and the actual attack on the salticid was seen in four. In the laboratory, five of the ant genera observed in the field were tested with four categories of salticids: (1) four myrmecophagic (i.e., ant‐eating) species, (2) six myrmecomorphic (i.e., ant‐like) species, (3) an ant‐associate species (i.e., a species that is neither myrmecophagic nor myrmecomorphic, but known to associate with ants), and (4) 14 ordinary species (i.e., species that are neither ant‐eating nor ant‐like, and are not known to associate with ants). In these tests the highest survival rates were observed in the myrmecophagic salticids, followed by the myrmecomorphic salticids, the ant‐associate species, and finally the ordinary species.

Optimal sample size methodology, which has been used by plant and marine ecologists for decades, is applied in this study to whole-community invertebrate data in the form of a case study. Wiegert’s method, based on maximizing the precision of biomass or catch data for the least cost in sampling or processing time, was conducted on guilds, habitat associations, and entire communities of tropical rice invertebrates at three crop stages (vegetative, reproductive, ripening) using five circular quadrats (35, 45, 55, 65, 80 cm in diameter) and a petrol-driven suction apparatus. Analysis of invertebrate samples and comparisons of different quadrat sizes showed that: (1) invertebrate abundance was a better predictor of processing time than was either species richness or species evenness for two of three crop stages; (2) average processing time per sample increased with crop age; and (3) size recommendations for one crop stage did not correspond to another for the same invertebrate group; however, after averaging over crop stages, one optimal quadrat size emerged for three out of six faunal groups. Unexpectedly, the optimal (and most practical) quadrat size determined for rice-invertebrate communities (35 cm diameter) was smaller than the majority (90%) of published studies have previously used, leading us to conclude that the majority of researchers (including the present authors) have used larger quadrats than were needed to obtain the same precision. Results of this case study underscore the need for researchers to conduct efficiency tests of their sampling program before starting large field trials and to resist the temptation of using published quadrat sizes whose optimality characteristics have not been field tested.

Soil sampling over a two-year period in Claveria, Northern Mindanao, Philippines, revealed the presence of five white grub species (Coleoptera: Scarabaeidae) in the deforested, infertile, and highly eroded grassland environment being converted to small farms. Population dynamics data point to Leucopholis irrorata (Chevrolat), Holotrichia mindanaoana Brenske, and H. flachi Brenske being biennial with Adoretus luridus Blanchard and Anomala humeralis Burmeister being annual species. The three biennial species are synchronized to even-numbered years. Small subpopulations of the biennial species show evidence of annual or allochronic cycles. L. irrorata has an annual cycle in other areas of the Philippines on sugarcane but takes two years to develop in Claveria probably due to infertile soils and a longer feeding period. Other subpopulations of young larvae and emerged adults occurring in the late rainy season were 'attempts' at multiple generations or delayed development, but were considered suicidal due to t...

Parental care, especially as it relates to our understanding of sociality, is a topic that has received considerable recent attention in research on spiders (Aviles, 1997). Predatory strategies, including foraging decisions, prey preferences and predatory versatility, have also been emphasized in the recent literature. The present paper is concerned with both of these areas, parental care and predatory strategies. Scytodes sp. indet. is a versatile predator that captures prey either in its web or away from webs, and prey capture may be either by ambush or by active pursuit regardless of whether in the presence and absence of webs. The web is a sparsely woven sheet across a concave upper leaf surface, with a three-dimensional tubular nest linked to the sheet via a small opening. Leaves may be green and living or brown and dead. In the field, a wide range of insects and spiders is taken, but jumping spiders (Salticidae) are the dominant prey. Predatory attacks are by spitting, with large prey being spat at repeatedly before being subdued. After spitting, the scytodid wraps prey in silk before feeding. Eggs are enclosed in a silk egg sac. The female uses her chelicerae to hold her eggs until hatching. After hatching, there is an extended mother–offspring association, with juveniles tending to remain in their mother's web until after the third moult. Females take prey to their juveniles and either feed alongside the juveniles or leave the juveniles to feed alone.

Rank-abundance curves, indices of community structure, and surrogate-based methods of biodiversity assessment were applied to invertebrate time-series data collected from a farmer's irrigated rice ( Oryza sativa L.) field on Luzon Island, Philippines. Canopy and floodwater invertebrates were vacuum- and strainer-sampled, respectively, at roughly weekly intervals after rice seedlings were transplanted up to harvest for a total of 8 sampling dates. The cumulative samples included 202 taxa and 9,570 individuals for the plant canopy and 180 taxa and 84,905 individuals for the floodwater. Rank-abundance curves revealed the following findings: (1) a 10,000-fold range in invertebrate abundance with many abundant taxa remaining abundant over all crop stages; (2) lower evenness (equitability) of invertebrate abundances in the floodwater than the plant canopy, due in large part to the numerical dominance (75%) of 2 crustaceans [ Heterocypris luzonensis Neale, Eucyclops serrulatus (Fischer)]; (3) the preponderance of natural enemies as the largest guild in number of taxa in both the canopy and floodwater, followed by herbivores, detritivores, and tourists (nonpredatory taxa with no known interaction except as prey to rice field predators); and (4) herbivore- and detritivore-dominated faunas typified early crop periods in the canopy and floodwater, respectively, followed by predator-dominated faunas in both systems at mid- and late-crop stages. Rates of community turnover generally increased with crop age in both the canopy and floodwater faunas with the former increasing faster than the latter. Of the 82 terrestrial taxa that were tested as surrogates of all canopy taxa, mymarid wasps ( Anagrus sp.) gave the best fit to the data; however, this taxon's sensitivity to single sampling dates made it and the other canopy taxa unsuitable surrogates of all canopy taxa. Conversely, of the 24 floodwater taxa tested, hydrophilid beetles and 4 other taxa (ostracods, gastropods, corixids and chironomids) passed our sensitivity test and were judged as acceptable surrogates for all floodwater taxa in this dry season rice ecosystem. We propose guidelines linking biodiversity concepts (rank-abundance curves, guilds, community metrics) and assessment methods (surrogate taxa) to agroecology for the purpose of enhancing understanding of tropical rice ecosystems for research and training programs.

In Los Banos in the Philippines (Laguna, Luzon), Scytodes sp. indet. is a web-building spitting spider (Scytodidae) that preys primarily on jumping spiders (Salticidae) and Portia labiata is an aggressive-mimic jumping spider that preys especially frequently on Scytodes. Tactics by which three species of Portia (P. africana, P. fimbriata, and P. labiata) and, for Portia labiata, three disjunct populations (Sri Lanka and, in the Philippines, Sagada and Los Banos) capture this especially dangerous prey are compared. Local adaptation to Scytodes by the Los Banos P. labiata is discussed. The Los Banos P. labiata uniquely made consistent use of tactics (soft plucking with palps and signal–detour–leap sequences) that were apparently responsible for greater prey-capture success and more effective avoidance of being spat on. Inter- and intraspecific differences were evident despite having used Portia that were reared in the laboratory with no prioir experience with scytodids.

Siler sp., Euophrys sp. 1 and 2, and six species of Chalcotropis feed on ants in nature. Capture techniques and preferences of each species were studied in the laboratory using a wide variety of ants and other insects. Siler sp. usually attacked ants, but not other insects, from directly behind. Euophrys sp. 1 and 2 consistently attacked ants, but not other insects, head on. Chalcotropis attacked large ants head on, but there was no particular orientation of attacks on small ants or on other prey regardless of size. All species tended to stab ants, but not other prey, several times before holding on. In three types of prey‐preference tests, each of the nine salticid species took dolichoderine, formicine, myrmicine, ponerine, and pseudomyrmecine ants in preference to a variety of other insects (aphids, bugs, caterpillars, cockroaches, crickets, flies, gnats, lacewings, mantises, may flies, midges, mosquitoes, moths, plant and leafhoppers, plant lice, and termites). Testing with laboratory‐reared s...

Prey‐preference behaviour of three species of araneophagic salticid (P. labiata from the Philippines and Sri Lanka, P. africana from Kenya and Uganda, and P. schultzi from Kenya) is studied in the laboratory for the first time. “Well‐fed” (7 day fast) and “starved” (14 day fast) males and females of each species have a pronounced preference for web‐building spiders over insects, and a less pronounced preference for salticid spiders over insects. Also, well‐fed and starved males and females of these species prefer web‐building spiders to salticids. Preferences for taxonomic type of prey are the same regardless of whether living, active prey or dead, motionless lures are used, suggesting that all these araneophagic salticids can distinguish between the different taxonomic categories of prey without reference to their different movement patterns. For each species, females—relative to males—preferred larger prey. When extra‐starved (21 day fast), males and females of all species appeared to take prey...

Arthropods constituting 51 families of 13 orders were collected from leaf litter during the early stages of decomposition. These groups were classified into their respective trophic categories based on mouthpart inference. These categories are as follows: chewing detritivores (15 families) > chewing predators (6 families) > chewing herbivores and sucking herbivores (5 families) > sucking predators (3 families) > chewing parasites and chewing omnivores (2 families). A simplified food web of the arthropods in leaf litter is also presented. Keywords - arthropod community, foodweb, leaf litter, trophic categories

The above-water food webs of arthropod communities in irrigated rice fields on Luzon Island, Philippines, were studied over the growing season at five sites (Los Baños, Cabanatuan, Bayombong, Kiangan, Banaue) ranging in elevation from 22 m to 1524 m. Arthropod populations were vacuum-sampled at roughly weekly intervals from the date after seedlings were transplanted to flowering at each site. Site- and time-specific webs were constructed from a 687-taxa cumulative Philippines web and time-series of species present. Taxonomic composition, food web structure, and arthropod phenology were broadly similar across different sites. Arthropod abundance was inversely associated with altitude across the five sites, but numbers of taxa and links and six food web statistics showed no obvious increasing or decreasing trend with altitude. The rise of taxa, links and mean food chain length over the growing season at each site reflected an increase in plant size with age and, at some sites, an orderly accumulation of newly arriving herbivore, predator, parasitoid and omnivore species. At each site, herbivores built up faster than predators and parasitoids, and predators arrived faster than parasitoids; the difference between the latest and earliest sampling dates of first arrivals, averaged over the five sites, was 38, 63 and 73 days for herbivores, predators and parasitoids, respectively. Site-to-site consistencies in food web properties and first arrivals suggest that such patterns may be influenced more by crop age than by geography or altitude. Sampled predator, parasitoid and omnivore taxa potentially encountered only a subset of their lifetime prey and predator species at any particular time in the rice field. Prey lists cumulated over time may underestimate the temporal specificity of predation by potential biological control agents. Research opportunities linking rice food webs and integrated pest management with East Indies biogeography are proposed.

Larval and adult predators comprise the largest component of the natural enemy fauna which attack the semi-aquatic rice caseworm Nymphula depunctalis (Guenee). Spiders, birds, and adult dragonflies/damselflies were the dominant predators of caseworm adults, while aquatic beetle larvae, aquatic bug nymphs and adults, and ants preyed on caseworm larvae. Egg parasitolds are unknown in nature and larval/pupal parasitoids are rare. A nuclear polyhedrosis virus, the only recorded pathogen, occurs but rarely. A ricefield pulmonate snail Lymnaea quadrasi (Mollendorff), which forages on algae, causes limited caseworm egg mortality in a passive and fortuitous manner. Water beetles—the dytiscid Cybister tripunctatus orientalis Gschwendtner and hydrophilid Sternolophus rufipes Fabricius—are voracious larval predators. Prey consumption by these water beetles is higher on older caseworm larvae whose larger size creates more movement while the larvae are crossing the water surface. Also, older caseworms are more prone to leave the protection of their cases while under attack. Younger caseworm larvae, however, tend to retract and remain motionless when attacked. The last instar dytiscid preyed on an average of 11.4 caseworm larvae per day while that of the hydrophilid preyed on 6.7 larvae per day.

The population dynamics of plant- and leafhoppers and associated predators and parasitoids at five rice sites in the Philippines, are compared. Twelve species of Auchenorrhyncha, nine Cicadellidae and three Delphacidae, were found in the samples. The order of abundance was Nephotettix virescens > Sogatella fucifera > Nephotettix nigropictus > Nilaparvata lugens. The dominant predators were mostly Heteroptera [Microvelia douglasi atrolineata (Veliidae) and Cyrtorhinus lividipennis (Miridae)] followed by spiders [Pardosa pseudoannulata (Lycosidae) and Callitrichia formosana (Linyphiidae)]. The delphacid and cicadellid populations were characterized by high initial densities, which reached a peak and were followed by a decline with low growth rates. Populations of heteropteran predators were similar, except that the peaks were at a later state and growth rates were higher. Predator diversity and evenness were significantly lower in Los Banos and Cabanatuan. The results are discussed in relation to implications to plant- and leafhopper management.

The arthropod community associated with irrigated rice grown in five sites in Luzon Island, Philippines, was analysed using guild categories. Phytophages and predators were predominant in all sites. The phytophage species were mainly Homoptera and dominated by Nephotettix virescens (Distant), N. nigropictus (Stål) (Cicadellidae), and Nilaparvata lugens (Stål) and Sogatella furcifera (Horváth) (Delphacidae). Predators were mainly Heteroptera with Microvelia douglasi atrolineata Bergoth (Veliidae), Mesovelia vittigera (Horváth) (Mesoveliidae), and Cyrtorhinus lividipennis Reuter (Miridae) as the most abundant species. Spiders were the next dominant group with Pardosa pseudoannulata (Böesenberg & Strand) and three species of Tetragnatha the most common. Differences in species diversity between the sites were easily differentiated using diversity indices. The relative differences in arthropod abundance, species richness and diversity may be attributed to the median temperatures, cropping patterns, and diversity in crop stages and germplasm in the sites. Predator-Homoptera correlations were significant in all cases. High positive correlations were obtained for veliids, spiders and Cyrtorhinus lividipennis, in most sites.

Four mechanisms within the resource concentration hypothesis influence Ostrinia furnacalis (Guenee) densities. Fewer ovipositing moths were attracted to (1) low density maize (

Rice Oryza sativa L. habitats were evaluated for their propensity to sustain rice tungro virus during the fallow period. Leafhopper vectors and associated natural enemies were sampled by a D-Vac suction machine from rice crops, nurseries, and fallow fields in Malaysia between December 1983 and May 1984. Leersia hexandra Sw. vegetation in wet, fallow rice fields harbored significantly higher densities of Recilia dorsalis (Motschulsky). Nephotettix virescens (Distant) was relatively abundant in second-stage rice nurseries. Nephotettix nigropictus (Stal) and N. malayanus Ishihara et Kawase were only moderately abundant or absent in the habitats sampled. Nephotettix parvus Ishihara et Kawase, a reported vector, was not caught. Spiders, in particular hunting spiders and orbweb weavers, numerically comprised the major natural enemy guilds in all habitats except in direct-seeded rice and single-stage nurseries, where predatory insects were more abundant. Egg parasitoids were the only parasitoid guild in all habitats except in L. hexandra vegetation where low numbers of nymphal-adult parasitoids were recovered as well. Oryza sativa, Fimbristylis miliacea (L.) Vahl and L. hexandra were the most commonly encountered tungro hosts. All habitats with rice potentially perpetuate tungro, particularly ratoon and volunteer rice which carry tungro and vectors to the next season crop and nurseries which are more susceptible to vectors and tungro infection. Fimbristylis miliacea may act as a tungro reservoir when rice is absent but cannot support vectors. Leersia hexandra harbors high densities of vectors but its role as a tungro host is more limited. Elimination of fallows with rice or tungro hosts is recommended as a preventive practice. However, weedy habitats without tungro hosts are beneficial as they harbor a variety of natural enemies of tungro vectors. Such vegetation should be tolerated where possible. Resistant varieties or selective insecticides should be used to prevent tungro infection in the nursery stage without destroying the diverse natural enemy complex.

Endotoxins from Bacillus thuringiensis (Bt) produced in transgenic pest-resistant Bt crops are generally not toxic to predatory and parasitic arthropods. However, elimination of Bt-susceptible prey and hosts in Bt crops could reduce predator and parasitoid abundance and thereby disrupt biological control of other herbivorous pests. Here we report results of a field study evaluating the effects of Bt sprays on non-target terrestrial herbivore and natural enemy assemblages from three rice (Oryza sativa L.) fields on Luzon Island, Philippines. Because of restrictions on field-testing of transgenic rice, Bt sprays were used to remove foliage-feeding lepidopteran larvae that would be targeted by Bt rice. Data from a 546-taxa Philippines-wide food web, matched abundance plots, species accumulation curves, time-series analysis, and ecostatistical tests for species richness and ranked abundance were used to compare different subsets of non-target herbivores, predators, and parasitoids in Bt sprayed and water-sprayed (control) plots. For whole communities of terrestrial predators and parasitoids, Bt sprays altered parasitoid richness in 3 of 3 sites and predator richness in 1 of 3 sites, as measured by rarefaction (in half of these cases, richness was greater in Bt plots), while Spearman tests on ranked abundances showed that correlations, although significantly positive between all treatment pairs, were stronger for predators than for parasitoids, suggesting that parasitoid complexes may have been more sensitive than predators to the effects of Bt sprays. Species accumulation curves and time-series analyses of population trends revealed no evidence that Bt sprays altered the overall buildup of predator or parasitoid communities or population trajectories of non-target herbivores (planthoppers and leafhoppers) nor was evidence found for bottom-up effects in total abundances of non-target species identified in the food web from the addition of spores in the Bt spray formulation. When the same methods were applied to natural enemies (predators and parasitoids) of foliage-feeding lepidopteran and non-lepidopteran (homopteran, hemipteran and dipteran) herbivores, significant differences between treatments were detected in 7 of 12 cases. However, no treatment differences were found in mean abundances of these natural enemies, either in time-series plots or in total (seasonal) abundance. Analysis of guild-level trajectories revealed population behavior and treatment differences that could not be predicted in whole-community studies of predators and parasitoids. A more conclusive test of the impact of Bt rice will require field experiments with transgenic plants, conducted in a range of Asian environments, and over multiple cropping seasons.

Summary 1. Data from a 645-taxa Philippines-wide food web and multiple regression models were used to predict population fluctuations of insect pests in a rice field. Independent variables of pest models included the biomass of rice plants in the field, the abundance of each pest, and the abundances of five highly correlated enemies of the pest, all as functions of time. 2. To test the ability of the models to reveal effects of insecticide spraying, a rice field at the International Rice Research Institute (IRRI) in the Philippines was divided into deltamethrin-sprayed and unsprayed plots. Data on the abundance of seven pest species (Nephotettix virescens, Recilia dorsalis, Sogatella furcifera, Nilaparvata lugens, Hydrellia philippina, Ne. nigropictus and Cofana spectra) and their natural enemies (predators and parasitoids) were collected during the dry season of 1990. 3. Spraying insecticide disorganized the population dynamics of insect species feeding in the IRRI field. Multiple regression models were less able in the sprayed plot than in the unsprayed plot to forecast the population fluctuations of pest species on the basis of various numbers and combinations of independent variables. For example, current pest abundance, by itself, was a significant predictor of future pest abundance for four of the seven pests (Ne. virescens, R. dorsalis, S. furcifera, H. philippina) in the unsprayed plot, but significant fits were found for only two pests (R. dorsalis, H. philippina) in the insecticide-sprayed plot. 4. In the unsprayed plot, independent variables were significant predictors of future pest abundance in four of seven initial models compared to one of seven models in the sprayed plot. Step-wise removal of independent variables in the models enhanced their forecasting power in both the sprayed and unsprayed plots, but significant models in the unsprayed plot nearly always outnumbered those in the sprayed plot. 5. In the unsprayed plot, Ne. virescens retained five of seven independent variables as significant predictors, compared to four for S. furcifera, three for C. spectra, and one for the remaining four pests. Classical models that contain one or two species as independent variables may not be sufficient to forecast future abundances of some Philippine rice pests in unsprayed and sprayed plots. 6. In general, models that included interaction terms and either the presence or absence of sprays among the independent variables did not improve the forecasting power of models in either the sprayed or unsprayed plot. 7. The methods developed here for studying the impact of spraying on the organization of arthropod communities in rice fields could be applied to other interventions

Experiments were conducted to determine the influence of a toxin-producing fungus on a rhizobial population in yeast-mannitol medium and in a tropical soil. The fungus, which was isolated from a highly weathered soil (Tropeptic Eutrustox), was identified as a Metarhizum sp. The density of rhizobial populations established in yeast-mannitol medium in the absence of the fungus was 10 5 times higher than that established in its presence. However, the fungus did not exert similar antagonistic influence on the rhizobial population incubated with it in the sterilized test soil. Rhizobial growth activity in yeast-mannitol medium was also insensitive to the presence of the fungus when the medium was amended with 1% (wt/vol) kaolinite or montmorillonite. The results suggest that clay minerals may be responsible for protecting rhizobia against toxin-producing fungi in soil.

Nitrogen-fixing activity and populations of nitrogen-fixing bacteria associated with two varieties of rice grown in dryland and wetland conditions were measured at various growth stages during the dry season. Acetylene reduction activities were measured both in the field and for the hydroponically grown rice, which was transferred from the field to water culture 1 day before assay. The activities measured by both methods were higher in wetland than in dryland rice. The population of nitrogen-fixing heterotrophic bacteria associated with rhizosphere soil, root, and basal shoots was determined by the most probable number method with semisolid glucose-yeast extract and semisolid malate-yeast extract media. The number of nitrogen-fixing bacteria was higher in wetland conditions than in dryland conditions. The difference between two conditions was most pronounced in the population associated with the basal shoot. The glucose medium gave higher counts than did the malate medium. Colonies were picked from tryptic soy agar plates, and their nitrogen-fixing activity was tested on a semisolid glucose-yeast extract medium. The incidence of nitrogen-fixing bacteria among aerobic heterotrophic bacteria in association with rhizosphere soil, root, and basal shoots was much lower in dryland rice than in wetland rice.