Antibiosis to Spodoptera frugiperda (Lepidoptera: Noctuidae) in chickpea genotypes

Chickpeas (Cicer arietinum L.) belong to the Fabaceae family and are one of the most grown crops in the world and an important source of protein for humans. Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that causes significant crop damage. The objective of this study was to examine antibiosis to S. frugiperda in chickpea genotypes. The following genotypes were studied: Jamu 96 and Blanco Sinaloa 92 (Mexico); Nacional 29 (Cuba); BG 1392 (Spain), and BRS Kalifa, BRS Cristalino, BRS Toro, Nacional 27, 004UP, 003UP, BRS Cícero, and BRS Aleppo (Brazil). The chickpea genotypes influenced the biological parameters of S. frugiperda, of which larval period, larval weight, and pupal period were most affected. Nacional 29 caused high mortality in the larval and pupal stages of S. frugiperda. The larvae on BRS Aleppo had the longest larval stage, lowest weight, and longest pupal stage. The genotypes Nacional 29, Nacional 27, and BRS Cícero showed antibiosis resistance to S. frugiperda. These genotypes could be used as a source of resistance to S. frugiperda in conjunction with other methods of pest control in integrated pest management programs for chickpea crops. These resistant genotypes could also be used as donor sources in breeding programs for insect resistance.

Soybean Leaf Age and Plant Stage Influence Expression of Resistance to Velvetbean Caterpillar and Fall Armyworm

Numerous species of herbivorous insects are associated with soybeans, including the specialist velvetbean caterpillar (VBC), Anticarsia gemmatalis, and the generalist fall armyworm (FAW), Spodoptera frugiperda. Expression of plant resistance is influenced by factors intrinsic to host plants, such as leaf age and plant stage, which can differentially affect specialist and generalist insects due to varying levels of plant defense and corresponding insect adaptation. In this study four experiments were carried out to test the hypotheses that levels of antibiosis-resistance to VBC and FAW in the resistant genotype PI 227687 and susceptible genotype IGRA RA 626 RR are related to leaf age and plant stage of soybean. Furthermore, the concentrations of nutrients and selected flavonoids were quantified to give insights on possible chemical mechanisms underlying the resistance. As results, development of VBC and FAW were negatively affected when larvae fed leaves of the resistant genotype, older leaves from the lower part of plants, or leaves from reproductive-stage soybeans. The effects were partly different for each insect species, and the generalist FAW was more affected by higher resistance levels in the older leaves of soybean than the specialist VBC. Distribution and concentrations of nutrients and flavonoids in soybean in function of leaf age and plant stage may explain the varying levels of antibiosis-resistance to VBC and FAW. These results can benefit developments of specific protocols for screening resistant soybean genotypes and pest management strategies focused in plant parts and growth stages that insect-resistance levels are lowest.

Inheritance of Antibiosis Resistance to the Dectes Stem Borer, Dectes texanus, in Soybean PI165673

Dectes texanus larvae girdles the stems of soybean and cultivated sunflowers causing significant yield losses in North America. The soybean Plant Introduction (PI) 165673 exhibits antibiosis resistance to the larval stage. The objectives of this study were: (1) to determine the inheritance of D. texanus resistance in PI165673; (2) evaluate PI165673 antibiosis resistance before 21 d post infestation; (3) evaluate girdling damage in PI16563 at the end of the season. K07-1544/PI165673 F2 and F2:3 populations were tested for resistance to D. texanus in 2011 and 2012, and PI165673 antibiosis resistance and girdling damage were evaluated in 2014. Segregation for resistance to D. texanus and heritability estimates in the F2 and F2:3 populations indicated that resistance was controlled by two genes with dominant and recessive epistasis. Antibiosis evaluations indicated: (1) PI165673 contained lower number of larvae and eggs relative to the number of oviposition punctures at 15 d post infestation; (2) the proportion of first-instar larvae was higher in PI165673 at 15 d post infestation; (3) larvae reach the sixth-instar stage in PI165673. None of the PI165673 plants were girdled at the end of the season. Identification of additional sources of D. texanus resistance is required to impair larval development in the stem.

Evaluation of antibiosis resistance in seven apple cultivars to Eotetranychus frosti (Tetranychidae)

Eotetranychus frosti (McGregor) (Tetranychidae) is a main pest of apple and some fruit trees in Iran. The life table parameters of E. frosti on seven apple cultivars (Red, Golab Kohanz, Gala Imperial, Gala Royal, Fuji, Granny Smith and Golden) at 27±1ºC, 50±10% RH and a photoperiod of 16: 8 (L: D) h were determined. The immature developmental times of E. frosti ranged from 6.50 days on Granny Smith to 18.31 days on Golab Kohanz. The lowest and highest survival rate for whole immature stages was 85.71% and 95.72% on Golab Kohanz and Red, respectively. Fecundity of E. frosti was affected by cultivars; varied from 60.43 eggs on Golab Kohanz to 110.19 eggs on Granny Smith. The intrinsic rate of natural increase (r) varied significantly among different cultivars in which the lowest value (0.119 day-1) was on Golab Kohanz and highest value (0.365 day-1) was on Granny Smith. The mean generation time (T) was shortest on Granny Smith (11.45 days) and longest on Golab Kohanz (30.09 days). According to the results, Granny Smith and Golab Kohanz were susceptible and resistant cultivars, respectively among the ones tested. The findings of this study provide new information that can be used to design a more comprehensive IPM program for this important pest.

Investigation of Insect Resistance Components in Wild Pigeonpea Cajanus Scarabaeoides

Cajanus scarabaeoides (L.) Thouars is the closest wild relative of cultivated pigeonpea, Cajanus cajan (L.) Millspaugh. However, unlike cultivated pigeonpea which is very susceptible to insects, especially Helicoverpa armigera (Hubner), this wild pigeonpea is strongly insect resistant. Since H. armigera causes damage to many important crops resulting in economic losses up to 2 billion USD/year, improvement in resistance to this insect in crops is highly desirable. Here we investigate insect resistance components in C. scarabaeoides and explore the possibility of transferring one or more of those factors to cultivated pigeonpea. A detached leaf assay was used to assess antibiosis and antixenosis resistance mechanisms in C. scarabaeoides. Artificial diet supplemented with lyophilised leaf powder was employed to investigate the antibiosis resistance mechanism. Data on larval mortality and larval and pupal weights were collected. Time taken for neonate larvae to pupate and for pupae to develop to the moth stage were determined through daily observations. Preliminary results showed that H. armigera larval weight was significantly reduced and larval development stages were prolonged when reared on different accessions of C. scarabaeoides as compared to the susceptible check, C. cajan (ICPL 87). Interspecific hybridization was carried out between C. scarabaeoides and a commercial pigeonpea variety. Results from insect challenge assays and trichome identification indicate that the hybrids have similar levels of insect resistance to their wild parent. Proteomic analysis is being used to identify possible antibiosis factors.

Barley Varieties Stoneham and Sydney Exhibit Mild Antibiosis and Antixenosis Resistance to the Wheat Curl Mite, Aceria tosichella (Keifer)

The wheat curl mite, Aceria tosichella (Keifer), devastates cereal crops worldwide by direct feeding damage and transmission of several deadly viruses. Deployment of cereal crop varieties resistant to A. tosichella is key for reduction of crop yield losses, and management of this mite and associated viruses that it transmits. Barley varieties resistant to A. tosichella are not known to exist. The objectives of this study were to determine if A. tosichella resistance exists in the barley varieties Sydney and Stoneham, which are resistant to the Russian wheat aphid, Diuraphis noxia (Kurjumov), and, further, to determine which categories mediate the resistance. Categories of resistance to both A. tosichella biotypes were evaluated independently in non-choice and choice experiments using wheat varieties Ike and OK05312 as susceptible and resistant controls, respectively. Sydney barley displays mild antixenosis and antibiosis resistance to A. tosichella biotype 1 and 2, respectively. Stoneham barley exhibits only mild antibiosis to biotype 2. No evidence for plant tolerance was found in either barley variety to either mite biotype.

Resistance of rice genotypes to Tibraca limbativentris (Hemiptera: Pentatomidae)

The Tibraca limbativentris is a pest that causes rice crop damage and may lead to grain yield reductions of up to 90%. The most commonly used tactic for T. limbativentris control is chemical, which causes adverse effects on the environment. This study was conducted to identify sources of antixenosis and antibiosis resistance to T. limbativentris mediated by the hardness and diameter of the stem of the rice plant. Antibiosis and antixenosis tests were carried out with 22 rice genotypes of Brazilian and Asian origin. The Canela de Ferro, BRS Esmeralda, and Desconhecido Branco genotypes had the lowest proportions of stems showing symptoms of the damage caused by T. limbativentris. Canela de Ferro, Primavera, and IR 22 genotypes had the lowest nymphs survivorship and the genotypes Marabá Branco, Marabá, Skirivimankoti, Pepita, BR IRGA 409, Curinga, IR 40, Bonança, Desconhecido Branco, Bico Ganga, Primavera, and BRS Esmeralda were the least attractive to the insects. The genotypes BRS Esmeralda, Primavera, Desconhecido Branco, and Canela de Ferro were resistant to the rice stalk stink bug by antibiosis and/or antixenosis. These genotypes can be used directly by rice farmers for T. limbativentris management. Molecular biology studies should be conducted to identify and characterize resistance genes in these genotypes so that they can be used in breeding programs.

Susceptibility of six corn varieties (Zea maysL.) to Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae)

Agricultural produce is commonly stored in warehouses after the harvest period, before being utilized and fulfilling the crop stock. However, crop threats are not only present during cultivation and harvest, but crops can also be infected during storage, which leads to agricultural loss. This research aimed to observe the resistance level of corn varieties of Bisma, Bisi 18, Bisi 19, Pioneer 21, Pioneer 29, and Pertiwi 3 to the Sitophilus zeamaispest of stored product insects. This resistance was based on the mechanism of non-preference (antixenosis) resistance, measured with the Free Choice Test Method (FCTM), and antibiosis resistance mechanism, measured with the No Choice Test Method (NCTM). The results showed that based on the susceptibility index (Dobie, 1974), corn varieties of Pertiwi 3 were categorized as resistant to S. zeamais pests, while the varieties of Bisi 19, Bisma, Bisi 18, Pioneer 21 and Pioneer 29 were moderately resistant.

Antibiosis and antixenosis resistance to oviposition by Bemisia tabaci (Gennadius) B biotype (Hemiptera: Aleyrodidae) in soybean genotypes

ABSTRACT: This study was aimed at assessing some biological parameters of Bemisia tabaci B biotype at immature stages to examine antibiosis in six soybean genotypes, besides antixenosis resistance to oviposition in choice and non-choice tests, under greenhouse and laboratory conditions. Between April 2016 and August 2016, bioassays were carried out at the Laboratory of Applied Entomology at College of Agricultural Sciences at Federal University of Grande Dourados (UFGD) Dourados (MS), Brazil. The following variables were evaluated: egg incubation period, nymphal and egg-to-adult duration, egg and nymph viability, and egg-to-adult survival on the soybean genotypes 68i70 RSF IPRO, M6210 IPRO, MS 947 IPRO, BMX Potência RR, M6410 IPRO, and ANTA 82 RR. Antixenosis resistance to oviposition by the silverleaf whitefly was found for MS 947 IPRO, while oviposition was highest for ANTA 82 RR, M6210 IPRO, and M6410 IPRO. The genotype MS 947 IPRO adversely affected egg and nymph viability, and egg-to-adult survival rates was the lowest among genotypes (59.75%), suggesting antibiosis resistance to this pest.

Studies on Biology and Antibiosis Resistance in Mango (Mangiferae indica) Varieties Against Mango Mealy Bug, Drosicha mangiferae Green (Hemiptera: Margarodidae)

Mango is known as king of fruits. Among mango pests, mango mealy bug, Drosicha mangiferae (MMB), is considered one of the most destructive pests of mango orchards and other plantations. Whenever it enters in any orchards it is difficult to eradicate it from those orchards. The experiment was conducted at Entomological Research Sub Station, Multan-Punjab, Pakistan, during 2009 and 2010, to evaluate fitness of mango mealy bug on different varieties of mango and biology on ‘Chaunsa’ variety. Mango mealy bug, Drosicha mangiferae Green (Hemiptera: Coccoidea: Margarodidae), is matter of concern, as it is widespread pest of woody plants even in urban areas. A study was conducted on cultivar resistance and fecundity of mango mealy bug. The ‘Chaunsa’ cultivar of mango proved highly susceptible to mango mealy bug with maximum number of eggs laid, i.e. 335.90, and maximum weight, i.e. 0.239 g of the female, was recorded on the cultivar ‘Chaunsa’. The maximum length, i.e. 1.63 cm, and width, i.e. 0.80 cm of female, was observed on ‘Chaunsa’, which showed a susceptible response and did not differ significantly with the width of female on ‘Black Chaunsa’. Regarding biology, the 1st instar male and female duration on an average is 56.3 days, whereas the 2nd instar has 26 days. In case of the 3rd instar, female has duration 19.5 days and male has three days. Male has pupal stage, while it is absent in female. On an average two study years, the ranking of susceptibility of mango cultivars was as under: ‘Chaunsa’ > ‘Black Chaunsa’ > ‘Malda’ > ‘Fajri’ > ‘Retaul-12’ > ‘Langra’ > ‘Sensation’ > ‘Sindhri’ > ‘Dusehri’ > ‘Sufaid Chaunsa’ > ‘Anwar Reutul’ and > ‘Tukhmi’.