No-choice Tests Research Articles

Chili pepper genotypes assay approach for resistance to Aphis gossypii (Hemiptera: Aphididae)

The cotton aphid (Aphis gossypii), is one of the most devastating insect pests for chili pepper that damages the crop and transmits several viruses. Thus far, there is no commercial chili cultivar with effective resistance to cotton aphids (CA). The present study aimed to develop a reliable and practical screening protocol in chili peppers for aphids resistance in the tropical areas. Three no-choice test methods i.e., seedling cage, detached leaf, and clip cage tests have been developed. The experiment was conducted in a randomized complete block design (RCBD) with four replications in a greenhouse at the Gunung Putri, Bogor, West Java, Indonesia. Seven chili pepper genotypes belong to the species Capsicum annuum L. provided by the Department of Agronomy and Horticulture, IPB University, Bogor, Indonesia were used in this study. Chili pepper resistance to aphids was observed through the number of aphids progeny, and aphids fecundity among the genotypes. Two chili genotypes consistently showed low infestation while other genotypes showed the highest infestation with three screening methods. All the methods have a high heritability value (90%–91%), indicating that the evaluated chili genotypes could be used to determine effective screening methods. The correlation between the detached leaf and clip cage tests was significant (r = 0.84, P ≤ 0.05). Therefore, the clip cage test could be used as a reliable and practical screening test for the assay of chili peppers resistance to CA infestation. These information will be helpful in the development of aphid resistant cultivars in the future.

Toxicity and Antifeedant Activity of Calotropis gigantea L. Leaf Extract Against Plutella xylostella L. (Lepidoptera: Plutellidae)

Many parts of the Calotropis gigantea plant are known to contain bioactive compounds, but leaves contain the most. This study aimed to determine the toxicity and antifeedant activity of C. gigantea leaves against Plutella xylostella. The study was carried out from November 2019 to July 2020. Toxicity was tested using the leaf dipping and spraying methods. Antifeedant activity was tested using a no-choice test and a choice test. Identification of the compound composition of the leaf extract of C. gigantea was carried out at the Integrated Research and Testing Laboratory, Gadjah Mada University. Extract toxicity data obtained were analyzed by Probit analysis. The results showed that the antifeedant activity of C. gigantea leaf extract a no-choice and with choice at each concentration had a significant effect on the consumption of P. xylostella larvae rations. The toxicity (LC50) of the leaf extract of C. gigantea to P. xylostella by the dipping method was 2,958 µgl-1 while the spraying application was 3.944 µgl-1. The composition of chemical compounds contained in the leaf extract of C. gigantea is saponins, alkaloids, flavonoids, tannins, phenols, terpenoids. With the composition of these chemical compounds, the leaf extract of C. gigantea has the potential as a source of vegetable insecticide compounds against P. xylostella.

Citric Acid As a Potential Molluscicide and Deterrent for the Invasive Slug Arion fasciatus

We investigated citric acid as a potential molluscicide and deterrent for the invasive slug species Arion fasciatus (Nilsson, 1823). To examine the efficacy of citric acid through ingestion or environmental exposure, slugs were given lettuce sprayed with 5% citric acid or 5% citric acid sprayed paper towels in no-choice tests. Slugs in choice tests were given both Romaine lettuce sprayed with 5% citric acid and DI water. We also investigated the impact of spraying Romaine lettuce seedlings with 5% citric acid to see if it impacts plant growth. No-choice tests revealed that environmental exposure to citric acid resulted in the eventual death of 64% of the slugs in the treatment group, while the ingestion of citric acid did not affect slug mortality. Choice tests revealed that citric acid significantly decreased Romaine lettuce herbivory. Romaine lettuce seedlings that were sprayed weekly for six weeks with 5% citric acid had a 31% lower biomass compared to the control, but no seedling deaths were observed. Overall, citric acid shows promise as a slug deterrent and molluscicide, though greenhouse and field trials are required to further elucidate its efficacy and impact on plants.

Antixenosis in cotton genotypes (Gossypium hirsutum var. marie galante) to Spodoptera frugiperda (Lepidoptera: Noctuidae) mediated by trichome and gossypol densities

Cotton (Gossypium hirsutum L.) is one of the most important crops in Brazil and pest incidence limits its yields. The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), native to tropical and subtropical America, spread and rapidly became an invasive pest worldwide. It is a polyphagous pest that feeds on up to 353 plant species including cotton. The objective of this study was to evaluate the antixenosis to S. frugiperda in 27 cotton genotypes, comparing varieties with non- commercial genotypes. The attractiveness was estimated in no-choice and free-choice tests, offering leaf discs of the 27 cotton genotypes to S. frugiperda, and counting the number of caterpillars feeding at 3, 5, 10, 15, and 30 minutes and 1, 2, 6, 12, and 24 hours after their release. The numbers of trichomes and gossypol glands per cm2 were measured on abaxial and adaxial surface. The free-choice test was performed in a randomized block design with the 27 genotypes (treatments) and 20 arenas (replicates). The no-choice assay was conducted as a completely randomized design with 18 genotypes and 20 replicates. The non-commercial genotypes PI0440, CE0467, PI0416, BA0512 and MA0425 presented antixenosis against S. frugiperda. In the free-choice test the cultivar BRS Buriti and the genotype PI0429 were the most attractive to S. frugiperda, while in no-choice test, the genotype PI0429 was the most attractive. High trichome density and gossypol glands did not influence the attractiveness of S. frugiperda in cotton genotypes, while the absence of trichomes was repellent to the caterpillars. There is polymorphism among cotton genotypes to attractiveness to the pest, and the genotypes with antixenosis can be used in future study in plant breeding program as donor source of resistance to S. frugiperda

Feeding behavior and development response of the perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) on multiple crop seeds combinations

• Effects of oilseed and cereal crops were studied on Nysius sp. • Multiple (MC)-and double (DC) seed combinations affected oviposition. • Higher number of eggs were laid on MC, with minimal nymph mortality. • The MC was ideal for normal development and positive adult performance. • Field distance maintain among crop fields is crucial for minimizing damages of Nysius sp. The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of several field crop species including perilla crop in Korea. Here, we investigated the oviposition, nymphal mortality, development, adult emergence, adult longevity, adult weight and female ratio of N. plebeius and N. hidakai on multiple (MC) and double (DC) combinations of five crop seed species: perilla [ Perilla frutescens (L.) Britton.], sesame ( Sesamum indicum L.), sorghum [ Sorghum bicolor (L.)], proso millet ( Panicum miliaceum L.), and foxtail millet ( Setaria italic L.) in no-choice test. The life-history variables of N. plebeius and N. hidakai were significantly influenced by the crop seed combinations. The most preferred crop seed combinations for oviposition were MC (perilla + sorghum + sesame + proso millet + foxtail millet), followed by DC (perilla + foxtail millet and perilla + sorghum), whereas the least preferred seed combination was DC (proso millet + foxtail millet). Both Nysius sp. were developed faster in MC (perilla + sorghum + sesame + proso millet + foxtail millet), with minimal nymphal mortality, higher adult emergence, longer adult longevity and heavier adult weight. The positive adult bug’s performance on the MC (perilla + sorghum + sesame + proso millet + foxtail millet) may be due to the nutrient contents and physicochemical components associated with the crop seeds. Further, the findings of this study are discussed in terms of bug's behavioral response to crop seed species combinations and management strategies of Nysius sp. as an alternative to chemical management.

Does the Presence of the Biological Control Agent, Hypena opulenta (Lepidoptera: Erebidae) on Swallow-Worts Deter Monarch Oviposition?

Invasive black and pale swallow-worts (Vincetoxicum nigrum (L.) Moench, and Vincetoxicum rossicum Kelopow), which are related to milkweeds, can act as ecological traps for monarch butterflies (Danaus plexippus L. (Lepidoptera: Nymphalidae)) as they lay eggs on them that fail to develop. A recently approved biological control agent against swallow-worts, Hypena opulenta Christoph, occupies the same feeding guild on swallow-worts as monarch larvae and could be perceived as a competitor to monarchs. We tested how the presence of this defoliating moth on swallow-worts may influence monarch host selection. In a two-year field experiment, we placed pale swallow-wort plants that were either infested with H. opulenta or noninfested as well as common milkweed (Asclepias syriaca L.), into monarch habitats to assess oviposition rates. In the laboratory, monarchs were either given a choice or not between milkweeds and black swallow-worts with or without H. opulenta. While monarchs strongly preferred common milkweed in the field, up to 25% of the eggs we observed were laid on pale swallow-wort, without preference for swallow-wort with (10.7%) or without (14.3%) H. opulenta. In laboratory choice and no-choice tests, monarchs did not lay any eggs on black swallow-wort, likely because of the long-term laboratory rearing on common milkweeds. Our results confirm that pale swallow-wort may act as an oviposition sink to monarchs in Michigan as well. Since the biological control program is still in its infancy, the nature of interactions between monarchs and H. opulenta may change as the biocontrol agent becomes more widespread.

The effect of pro-ecological procedures and plant injury on the content of free phenolic acids in winter wheat and on the feeding and development of Oulema melanopus

Under laboratory conditions we have investigated the effect of the application of pro-ecological procedures (effective microorganisms and biostimulant Asahi SL) and plant injury on the production of free phenolic acids in winter wheat and on the feeding and development of Oulema melanopus. Wheat plants before reaching the BBCH 32 stage (the beginning of stem elongation) were treated with effective microorganisms and the biostimulant Asahi SL. Then, for 2 days, some of the plants were injured by O. melanopus and some were uninjured. The influence of factors was investigated in conditions under which the cereal leaf beetle had the possibility to choose their food (no-choice test or choice test). It was found that wheat plants produce on average 0.172% DM of free phenolic acids. It has been shown that O. melanopus males and females preferred wheat previously uninjured. Also, irrespective of whether the plants were previously injured or uninjured, the females of that pest species always that caused areally more extensive leaf losses than the males. Treating plants with effective microorganisms and biostimulant Asahi SL is a secondary factor, as compared to previous wheat injury. Additionally, in choice tests, both males and females O. melanopus much preferred feeding on plants unprovided with preparations, whereas in no-choice tests, the application of pro-ecological procedures does not reduce egg laying by pests, does not adversely affect embryogenesis length and does not reduce hatching L1.

Live black soldier fly larvae (Hermetia illucens) provisioning is a promising environmental enrichment for pigs as indicated by feed- and enrichment-preference tests

Live black soldier fly larvae (BSFL) could function as environmental enrichment for pigs as they are edible, odorous, manipulable, and destructible, though the interest of pigs in live BSFL is unestablished. In this study, three trials were performed to assess this interest in order to verify the suitability of live BSFL as enrichment. Eight (Trial 1 & 2) and 16 (Trial 3) pairs of weaned pigs were included. In Trial 1, the relative motivation of pigs to consume live BSFL compared to corn, raisins and feed pellets was evaluated in no-choice and subsequent two-choice preference tests including all (combinations of) feed items. In Trial 2, the feed items in the no-choice and two-choice tests were provided in tubes that had to be rooted or pushed to access the feed items. In this trial BSFL, corn, feed pellets, and empty tubes were compared. In Trial 1 & 2 each day had two 15 min tests occurring six hours apart. In Trial 3 the long-term interest in live BSFL provided in the tubes for a 5-day period was compared to feed pellets provided in tubes, to jute sacks, and to rubber balls attached to chains. Tubes with live BSFL or pellets were refilled every morning. The relative interest was determined through intake of feed items and/or time spent interacting with the items, as measured by 1.5- or 1 min scan sampling. In Trial 3, the time spent on oral manipulation of pen mates was also scored through scan sampling. In all trials the interaction with and consumption of live BSFL was significantly higher compared to the other items, indicating a clear preference for live BSFL, and pigs remained engaged with BSFL as long as they were accessible. In Trial 3, interest in live BSFL decreased on day 5 compared to day 1, interest in jute sacks and feed pellets decreased on day 3 compared to day 1, and interest in rubber balls attached to chains was continuously low. Pigs also spent less time on oral manipulation of pen mates when having access to live BSFL, pellets, or jute sacks, compared to rubber balls attached to chains. Overall, pigs showed high and extended interest in live BSFL, confirming their suitability as edible environmental enrichment. Pigs were willing to work for access to live BSFL by rooting and pushing tubes, which can be employed when providing live BSFL as enrichment commercially.

Oviposition preference and two-sex life table of Plutella xylostella and its association with defensive enzymes in three Brassicaceae crops

The diamondback moth (Plutella xylostella) is a worldwide devastating pest specialized on Brassicaceae plants, including three main vegetables of China i.e., cabbage, Chinese cabbage, and radish. To develop a cost-effective control program, we compared the adult oviposition preference and life table parameters of P. xylostella on these three crops. In the no-choice and choice oviposition tests, P. xylostella females laid more eggs on Chinese cabbage than radish and cabbage. In addition, P. xylostella larvae consumed more leaves when feeding on Chinese cabbage compared with other plants. The age-stage two-sex life table indicated that the intrinsic rate of increase (r) of P. xylostella was higher on Chinese cabbage (0.233 d−1) than radish (0.203 d−1), and cabbage (0.135 d−1). The fecundity was the highest on Chinese cabbage, while developmental duration from egg to adult on Chinese cabbage was significantly shorter. Chinese cabbage leaves exhibited lower activities of defensive enzymes and significantly higher total protein content, which may account for the higher preference and performance of P. xylostella on Chinese cabbage. These results suggest that Chinese cabbage is highly susceptible to P. xylostella and needs more frequent monitoring and control strategies against this pest, although field trials are needed to confirm these findings.

Morpho-agronomy performance, seed nutrition content, and Aphis craccivora resistance of cowpea (Vigna unguiculata) genotypes

Abstract. Sas MGA, Wahyu Y, Syukur M, Hidayat P. 2021. Morpho-agronomy performance, seed nutrition content, and Aphis craccivora resistance of cowpea (Vigna unguiculata) genotypes. Biodiversitas 22: 4320-4326. Cowpea (Vigna unguiculata subsp. unguiculata) is an agricultural commodity that can be a source of vegetable protein and replace the need for soy as a food ingredient. The wide adaptability under sub-optimum conditions placed cowpeas as the choice to be developed. This study aimed to evaluate the cowpea genotype’s agronomic performance and resistance to Aphis craccivora to be proposed as superior genotypes. Observations were made on the morpho-agronomic characters, including the color of the young pods and dry seeds, the number of pods, the productivity of fresh pods and dried seeds, and the nutrition content. The resistance to Aphis craccivora was evaluated using a no-choice test whole plant for the resistance and tolerance evaluation. This study showed that the productivity of young pods (4.86-15.13 tons ha-1), dry seed productivity (0.83-2.71 tons ha-1). The protein content differed significantly among the 20 genotypes ranging from 19.24% to 24.45%. Aphid infestation significantly inhibited plant growth compared with non-infested plants. Infestation of Aphis craccivora decreased the dry weight of the plant by about 20% to 70%. Based on the aphid population, the 20 genotypes were classified into medium-high to very high aphid damage intensity.

How the seed coat affects the mother\u2019s oviposition preference and larval performance in the bean beetle (Acanthoscelides obtectus, Coleoptera: Chrysomelidae, Bruchinae) in leguminous species

BackgroundThe host specificity and host range of the dry bean beetle, Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae), a seed predator of beans, is poorly known. In addition, the female oviposition preference and larval performance relationship is complicated by the respective importance of seed coat and cotyledon, because, paradoxically, females lay eggs on the basis of stimuli of the seed coat alone, without directly being able to assess the quality of the cotyledon’s suitability for larval development. Conversely, the thickness of seed coat may prevent first instar larvae from entering the seeds, even if cotyledons are suitable for development.MethodsThe seeds of 62 leguminous species and 75 cultivars and accessions occurring in Hungary were evaluated for preference-performance relations. The preference of female bean beetles for seeds was measured in no-choice egg-laying tests. The ability of first instar larvae to overcome the seed coat as a physical barrier was tested with intact seed coat, while pre-drilled seed coats allowed the larvae to assess the suitability of cotyledon for development. The number of emerging adults was recorded. The thickness of seed coats and the weight of seeds were measured. Nonparametric tests and logistic regression were used for the statistical analyses of data and effect sizes were also calculated.ResultsSeeds of 18 leguminous species (35% of them Lathyrus) supported larval development to adults if the seed coat was pre-drilled; however, only nine leguminous species supported development to adults if the seed coat was intact. Seed coat thickness beyond a critical threshold of 0.1 mm strongly influenced survival of first instar larvae. There was no overall positive correlation between oviposition preference and larval performance, except for 16 so-called acceptable non-hosts (Kendall’s τ = 0.3088). A. obtectus females also showed an ovipositional hierarchy of legume species even in no-choice tests.ConclusionsThe results suggest that whereas the use of some acceptable non-host species by the A. obtectus is possible in seed stores, the same is unlikely under outdoor conditions, where the recognition of a diverse set of seed pod-related compounds would be necessary to induce egg-laying.

Efficacy of brodifacoum 50ppm-based rodenticidal baits on the control of the mice Mus musculus in Cotonou

In Benin, cities with a high population rate such as Cotonou are colonized by several species of rats such as Rattus rattus, Mastomys sp, Mus musculus and Crocidura olivieri which are agents of destruction of stored products especially in the area of the big Dantokpa market. Indeed, anticoagulants are the most frequently used rodenticides worldwide in the fight against these rodents. However, very few studies have evaluated the biological efficacy of high dose rodenticides on the resistant strain of the mouse population (Mus musculus) in Cotonou. The present work compared the efficacy of three original brodifacoum-based baits: vertox pellets, vertox block and vertox past on the wild domestic mouse strain (Mus musculus) in Cotonou. The results showed that in the no-choice feeding tests in the laboratory, 100% of the animals died in all experimental groups and zero in the control groups. Time to death did not differ significantly between vertox pellet and vertox block bait in either test/feeding regime. However, with vertox past, a relatively longer time to death was observed. The three baits were therefore tested under field conditions on mouse populations and showed the following efficacy in terms of mouse mortality after three weeks: 83.33% with vertox pellets; 72% with vertox block and 95.33% with vertox past. The results obtained highlighted the good efficacy of the three brodifacoum-based baits in heterogeneous (resistant or not) mouse populations. However, an additional study is needed with the same anticoagulants only on resistant rodent populations.

Efficacy of the parasitoid, Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) against Myzus persicae (Sulzer) (Hemiptera: Aphididae) infesting rapeseed-mustard

• The parasitoid, D. rapae could parasitize on all nymphal instars of M. persicae . • The parasitoid showed a type II functional response to M. persicae . • An inverse relationship between parasitoid density and search-efficiency was noted. • Performance of D. rapae was better while parasitizing younger instars of M. persicae. Efficacy of Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae) was determined by studying its biological and behavioural attributes on the aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). Total developmental duration of the parasitoid was longer in younger instars compared to that in older instars of aphid. Host age negatively affected the oviposition period and fecundity of the ovipositing parasitoid. Survival of the immatures was higher in older than the younger instars of the aphid. Sex ratio for the parasitoid was female-biased. Longevity of female parasitoid was higher while parasitizing aphid nymphs of younger age groups (1–2 days old) compared to that of older age groups (4–5 days old). Parasitoid showed a higher preference towards second instar of M. persicae both in choice and no-choice tests. Results on mutual interference revealed that per capita searching efficiency decreased from 0.91 to 0.07 as parasitoid densities increased from 1 to 8. Logistic regression exhibited a type II functional response for D. rapae . The estimated values of search-efficiency (a) and handling time (T h ) were 0.038 h −1 and 1.59 h, respectively. The maximum parasitization rate was 15.08. This investigation suggests that D. rapae could be an effective candidate for augmentative biological control of M. persicae which infests several plant species of economic importance.

Host Specificity and Preliminary Impact of Lepidapion argentatum (Coleoptera, Brentidae), a Biocontrol Candidate for French Broom (Genista monspessulana, Fabaceae).

Simple SummaryFrench broom is a leguminous shrub that is an internationally significant invasive alien weed in California and nearby US states that competes with native vegetation and increases the risk of wildfires. French broom originates from the Mediterranean region and is the target for classical biological control. Exploration for prospective biological control agents in the native region of Western Europe resulted in the collection of the weevil Lepidapion argentatum. We conducted preliminary field studies showing that this weevil can impact seed production in the native habitat. We also measured the specificity of this candidate biocontrol agent in laboratory conditions on 36 plant species growing in California and Australia. Our data showed that, in no-choice tests, seven species were directly negatively impacted by gall formation induced on plant stems by the weevil, but at different levels, including two lupine species commonly distributed in California. Further experiments are needed to ascertain the safety of this candidate biocontrol agent prior to release.French broom (Genista monspessulana) (Fabaceae) is a perennial species native to the Mediterranean basin. Introduced in the 19th century as an ornamental plant, it is currently invasive in California and Australia. The current research is focused on biocontrol with the use of the phytophagous weevil Lepidapion argentatum (Brentidae). Its capacity to develop both in the stem galls and pods of French broom makes it a promising candidate. The impact on the reproduction of French broom was studied in Southern France and revealed that it could effectively reduce the number of viable seeds by 18.8%, but also increased the number of aborted seeds by 10% within the attacked pods. To evaluate the specificity of L. argentatum, choice and no-choice tests were performed in 2012 and 2015 on a total of 36 non-target closely related species. Results revealed the presence of galls and larvae in the stems of seven species, including two endemic Californian lupines; i.e., Lupinus arboreus blue and Lupinus chamissonis. In the future, new tests will be conducted to determine if L. argentatum is able to complete its entire development lifecycle on the non-target species where galls have previously been observed.

Determining the host range of Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae), a candidate biological control agent for diamondback moth Plutella xylostella linnaeus (Lepidoptera: Plutellidae) in Canada

Before a non-native agent is introduced for the classical biological control of a pest, its host specificity must be determined. We assessed the host specificity of Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae), a solitary pupal endoparasitoid being considered for biological control of the diamondback moth Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) in Canada. In black-box no-choice tests on nine non-target species, D. collaris successfully parasitized other species in the genus Plutella (the introduced Plutella porrectella Linnaeus and the native Plutella armoraciae Busck) as well as another introduced agricultural pest, the leek moth Acrolepiopsis assectella (Zeller) (Lepidoptera: Glyphipterigidae). This suggests that the fundamental host range of D. collaris includes other species in the Plutellidae, as well as Glyphipterigidae that are ecologically and morphologically similar to diamondback moth. Field tests in Switzerland comparing parasitism by D. collaris on sentinel diamondback moth pupae and leek moth pupae in both canola and leek fields revealed no parasitism of leek moth in leek fields, indicating that the ecological host range of D. collaris is in fact more restricted. Because of this, it would be premature to discount D. collaris as a potential biological control agent for diamondback moth in Canada.

Varietal Screening of Rice Genotypes for the Rice Weevil, Sitophilus oryzae (Linnaeus) (Curculionidae: Coleoptera) at Laboratory Condition

The rice weevil, Sitophilus oryzae (Linnaeus) is a major pest of rice at storage condition in Nepal. A lab experiment was conducted for varietal screening of rice genotypes against S. oryzae at the National Rice Research Program, Hardinath, Dhanusha, Nepal in 2020. The study was carried out in Completely Randomized Design (CRD) in a three replicates. Fifty gram of each seven popular rice genotypes i.e Sambha Mansuli Sub-1, Ramdhan, Radha-11, Bahuguni-1, Bahuguni-2, Hardinath-2 and Lalka Basmati were used to screen the potential weevil resistant rice cultivars. Ten pairs of newly emerged adult S. oryzae of uniform age obtained from stock culture were released in each plastic jar in no-choice tests, while twenty five pairs of S. oryzae were released in the center, in choice tests. Results were evaluated based on the grain damage percent, weight loss percent, and total live weevil population for 90 days from the date of experiment. The result demonstrated that Lalka Basmati was the least damaged rice cultivar followed by Bahuguni-2. The highest weevil population over 90 days was recorded in Sambha Mansuli Sub-1 followed by Hardinath-2 and the least weevil population was found on Lalka Basmati followed by Bahuguni -2 in both test conditions. Lowest to highest damage ranking of rice genotypes was: Lalka Basmati<Bahuguni-2<Bahuguni-1<Radha-11<Ramdhan<Hardinath-2<Sambha Mansuli Sub-1. Thus, promotion of Lalka Basmati & Bahuguni-2 varieties is recommended to reduce the infestation of rice weevil in the storehouse condition. This information is useful for host plant resistant breeding program for the plant breeder.

No-choice risk assessment of Gratiana boliviana, a potential biological control agent of Solanum viarum in Australia

ABSTRACT Tropical soda apple (Solanum viarum), first detected in Australia in 2010, is a weed of agricultural significance as it reduces cattle stocking rates and limits stock movement. Gratiana boliviana (Coleoptera: Chrysomelidae) is an approved biological control agent for S. viarum in the United States of America (USA). Although the host specificity of G. boliviana has been extensively tested in the USA, additional no-choice tests were conducted to determine if the beetle is sufficiently host specific for release in Australia. The host test list included Solanum species native to Australia, as well as agriculturally important species that had been tested previously. Both adult and larval no-choice tests indicate that G. boliviana does not perform equally well across the target weed S. viarum and the other plant species included in the tests. Oviposition was observed on only two plant species besides the target weed, with significantly more eggs laid on S. viarum (19.5 ± 0.4 eggs/plant), followed by S. brownii (2 ± 0.4 eggs/plant) and S. melongena (1.8 ± 1.5 eggs/plant). Ninety per cent of eggs laid on S. viarum developed to adults, whereas only one egg laid on S. melongena completed development. Larval no-choice feeding assessments indicate that larval survival and development is highest on S. viarum (80%) followed by S. brownii (30%) and S. melongena (20%) and to a much lesser extent on S. lithophilum (2.5%). Our results contribute to the evaluation of the risk of potential off-target effects by G. boliviana feeding and development on native Australian or agriculturally important Solanum species.

In the tripartite combination ozone-poplar-Chrysomela populi, the pollutant alters the plant-insect interaction via primary metabolites of foliage

Ozone (O3)-induced metabolic changes in leaves are relevant and may have several ecological significances. Here, variations in foliar chemistry of two poplar clones (Populus deltoides × maximowiczii, Eridano, and P. × euramericana, I-214) under a chronic O3 treatment (80 ppb, 5 h d−1 for 10 consecutive days) were investigated. The aim was to elucidate if leaf age and/or O3-sensitivity (considering Eridano and I-214 as O3-sensitive and O3-resistant, respectively) can affect suitability of poplar foliage for Chrysomela populi L. (Coleoptera Chrysomelidae), in terms of palatability. Comparing controls, only low amino acid (AA) contents were reported in Eridano [about 3- and 4-fold in mature and young leaves (ML and YL, respectively)], and all the investigated primary metabolites [i.e. water soluble carbohydrates (WSC), proteins (Prot) and AA] were higher in YL than in ML of I-214 (+23, +54 and + 20%, respectively). Ozone increased WSC only in YL of Eridano (+24%, i.e. highest values among samples; O3 effects are always reported comparing O3-treated plants with the related controls). A concomitant decrease of Prot was observed in both ML and YL of Eridano, while only in YL of I-214 (−41, −45 and −51%, respectively). In addition, O3 decreased AA in YL of Eridano and in ML of I-214 (−40 and −14%, respectively). Comparing plants maintained under charcoal-filtered air, total ascorbate (Asc) was lower in Eridano in both ML and YL (around −22%), and abscisic acid (ABA) was similar between clones; furthermore, higher levels of Asc were reported in YL than in ML of Eridano (+19%). Ozone increased Asc and ABA (about 2- and 3-fold, respectively) in both ML and YL of Eridano, as well as ABA in YL of I-214 (about 2-fold). Comparing leaves maintained under charcoal-filtered air, the choice feeding test showed that the 2nd instar larvae preferred YL, and the quantity of YL consumed was 9 and 4-fold higher than ML in Eridano and I-214, respectively. Comparing leaves exposed to O3-treatment, a significant feeding preference for YL disks was also observed, regardless of the clone. The no-choice feeding test showed that larval growth was slightly higher on untreated YL than on untreated ML (+19 and + 10% in Eridano and I-214, respectively). The body mass of larvae fed with O3-treated YL was also significantly higher than that of larvae fed with untreated YL (3- and 2-fold in Eridano and I-214). This study highlights that realistic O3 concentrations can significantly impact the host/insect interactions, a phenomenon dependent on leaf age and O3-sensitivity of the host.

Comparative study of predation, preference and switching behaviors of two predatory mite Neoseiulus californicus and Amblyseius swirskii (Acari: Phytoseiidae)

Predatory mites have an incredible role in the suppression of spider mites in modern agriculture. The present study compared some behavioral traits of two predatory mites, namely Neoseiulus californicus McGregor and Amblyseius swirskii Athias-Henriot in response to different life stages of two-spotted spider mite, Tetranychus urticae Koch. In no-choice predation test, both predators had a higher predation rate on larval than other developmental stages of the prey. In this assay, the lower predation rate of A. swirskii was recorded on the egg stage, which was observed on the adult female for N. californicus. With one exception, the results obtained from the predation test in choice conditions confirmed these observations. In the choice test, both predators had a lower consumption rate on different stages of prey than no-choice ones. To investigate the predation preference of predatory mites, Manly’s preference index (β) was used. With respect to this index, both predators significantly preferred the larval stage than other developmental stages of T. urticae. Although N. californicus exhibited a lower preference to the female prey, in the case of A. swirskii, the lower preference to deutonymph and female was observed. Our findings also revealed that both predatory mites had no switching behavior from preferred stages to non-preferred ones, indicating that reducing the ratio of preferred stage in the experimental arena has no detectable effect on the predation preference of both predators.

Is the stem boring weevil Apocnemidophorus pipitzi (Coleoptera: Curculionididae) host specific to Schinus terebinthifolia (Sapindales: Anacardiaceae)?

ABSTRACT Brazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), is an ornamental shrub from South America that is invasive in Florida, California, Hawaii and Texas, USA and has become a global invader. Exploratory surveys were conducted in Argentina, Brazil, and Paraguay to discover natural enemies as possible biological control agents. One of the insects collected was subsequently identified as the stem boring weevil Apocnemidophorus pipitzi (Faust). The weevil was found at several localities in Paraguay in April 2007 and transported to Florida, USA, for biological and host range studies. Laboratory no- choice, and multiple-choice tests were performed to determine if A. pipitzi was suitably host specific for release as a biological control agent of Brazilian peppertree in Florida. In total, 79 North American plant species in 40 families and 28 Orders were tested. In the no-choice tests, complete development was significantly higher on Brazilian peppertree, Hardee peppertree, Schinus polygama (Cav.) Cabrera & I.M. Johnst., the invasive ornamental Chinese pistache, Pistacia chinensis Bunge and cultivated pistachio nut, Pistacia vera L. Both Pistacia spp. are chemically related to Brazilian peppertree. However, when given a choice, the stem boring weevil A. pipitzi reproduced only on Brazilian peppertree and the invasive congeneric Hardee peppertree. Overall, results of laboratory host range testing showed the stem boring weevil A. pipitzi is a Schinus specialist. This finding is consistent with field observations, museum records, and the preference-performance hypothesis, where larval survival, growth and normal development are maximised on plants selected for oviposition by the females.