Reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) in Eggs of Nezara viridula (Hemiptera: Pentatomidae) of Different Ages

The study of the interaction between parasitoid and host, especially the age of these organisms, is an important step towards the implementation of biological control programs. Therefore, we investigated the performance of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) parasitizing eggs of Nezara viridula (Hemiptera: Pentatomidae), considering different ages of the parasitoids and the host. We performed four laboratory bioassays: two using females of O. submetallicus and Trissolcus sp. aff. urichi at 24, 48, 72, 96, 120, or 144 hours of age exposed to parasitism in N. viridula eggs (24 h) and two trials with N. viridula eggs at 24, 48, 72, 96, 120, or 144 hours exposed to the parasitism of O. submetallicus and Trissolcus sp. aff. urichi (24 h). We evaluated the percentage of parasitism and emergence, life cycle length, progeny, sex ratio, and the longevity of the parasitoids. The parasitism of O. submetallicus in N. viridula eggs was influenced by the age of the parasitoid, 120 hours being the minimum to obtain better parasitism. From this age on, there is interference in the longevity of the progeny. Trisolcus sp. aff. urichi, at all ages, parasitized N. viridula eggs relatively well, but with almost no emergence of the parasitized eggs. Females of O. submetallicus parasitized and developed in eggs of N. viridula of all ages. Females of Trissolcus sp. aff. urichi parasitized their host, but there was barely any emergence. These pieces of information regarding the breeding methodology contribute to the implementation of new protocols for the multiplication of these parasitoids in the laboratory, and later, their release in the field.

Development of a Method for Rearing Nezara viridula (Heteroptera: Pentatomidae) on a Semi-solid Artificial Diet

A method for rearing the southern green stinkbug, (Nezara viridula L.) (Heteroptera: Pentatomidae), using a modified lygus semi-solid artificial diet was developed. First to second-instar nymph were reared in a density of 631.5 ± 125.05 eggs per Petri-dish (4 cm deep × 15 cm diam). Second instar to adult were reared in a density of 535.0 ± 112.46 s instar nymphs per rearing cage (43 × 28 × 9 cm). Mating and oviposition occurred in popup rearing cages (30 × 30 cm), each holding 60–90 mixed sex adults of similar age. Adults emerged 35.88 ± 2.13 d after oviposition and survived for an average of 43.09 ± 9.53 d. On average, adults laid 223.95 ± 69.88 eggs in their lifetime, for a total production of 8,099 ± 1,277 fertile eggs/oviposition cage. Egg fertility was 77.93% ± 16.28. Egg masses held in petri-dishes had a total hatchability of 79.38% ± 20.03. Mortality of early nymphs in petri-dishes was 0.64% ± 0.12 for the first instar and 1.37% ± 0.45 for second instar. Late nymphal mortality in rearing cages was 1.41% ± 0.10, 3.47% ± 1.27, and 4.72% ± 1.29 for the third, fourth, and fifth instars, respectively. Survivorship from nymphs to adults was 88.48% ± 2.76. Using artificial diet for rearing N. viridula could reduce cost by avoiding time-consuming issues with daily feeding fresh natural hosts and insect manipulation. It could increase reliability and simplicity of bug production, which should facilitate mass rearing of its biological control agents.

Trichoderma harzianum Strain T22 Modulates Direct Defense of Tomato Plants in Response to Nezara viridula Feeding Activity

Plant growth-promoting fungi belonging to genus Trichoderma are known to help plants when dealing with biotic stressors by enhancing plant defenses. While beneficial effects of Trichoderma spp. against plant pathogens have long been documented, fewer studies have investigated their effect on insect pests. Here, we studied the impact of Trichoderma root colonization on the plant defense responses against stink bug feeding attack. For this purpose, a model system consisting of tomato plant, Solanum lycopersicum cv Dwarf San Marzano, Trichoderma harzianum strain T22 and the southern green stink bug, Nezara viridula, was used. We firstly determined stink bug performance in terms of relative growth rate and survival on tomato plants inoculated by T. harzianum T22. Then, we evaluated relative expression of plant defense-related genes on inoculated plants induced by stink bug feeding. We found evidence that T. harzianum T22 affects tomato defense responses against N. viridula nymphs leading to reduction of growth rate. Our results also showed that T. harzianum T22 enhances plant direct defenses by an early increase of transcript levels of jasmonic acid marker genes. Yet this effect was time-dependent and only detected 8 h after herbivore induction. Taken together, our findings provide better understanding on the mechanisms underlying tomato induced resistance against herbivorous stink bugs.

Patogenisitas Beauveria bassiana (Bals.) Viull. yang Diisolasi dari Beberapa Jenis Inang Terhadap Kepik Hijau, Nezara viridula L. (Hemiptera: Pentatomidae)

Kepik Hijau (Nezara viridula L.) merupakan hama penting bagi beberapa tanaman pangan seperti kedelai, padi dan jagung. Salah satu upaya untuk mengendalikan hama adalah dengan pemanfaatan entomopatogen, seperti virus, bakteri maupun jamur. Salah satu jamur entomopatogen yang berpotensi untuk dieksploitasi adalah Beauveria bassiana yang mempunyai berbagai jenis inang. Belum diketahui patogenesitas B. bassiana yang diisolasi dari beberapa jenis inang terhadap hama kepik hijau (N. viridula), untuk itulah penelitian ini dilakukan dengan tujuan untuk mengetahui patogenesitas B. bassiana yang diisolasi dari inang yang berbeda terhadap hama kepik hijau (N. viridula). Penelitian ini dilakukan di Laboratorium Agens Hayati (LAH) Kalasey, Balai Perlindungan dan Pengujian Mutu Tanaman Pangan dan Hortikultura (BPPMTPH), Dinas Pertanian dan Peternakan Daerah Provinsi Sulawesi Utara. Penelitian dilakukan secara in- vitro dengan menggunakan Rancangan Acak Lengkap (RAL) dengan 6 perlakuan yaitu (Kontrol negatif , N1: suspensi B. bassiana isolat WBC (wereng batang coklat), N2: suspensi B. bassiana isolat Jati Sari sebagai kontrol positif (rekomendasi Kementan), N3: suspensi B. bassiana isolat Paraeucosmetus pallicornis (kepik hitam), N4: suspensi B. bassiana isolat Leptocorisa acuta (walang sangit) dan N5: suspensi B. bassiana isolat Scotinopara coarctata (kepinding tanah). Perlakuan menggunakan konsentrasi atau kerapatan konidia 109/ml air, dengan 5 ulangan. Data dianalisis dengan Uji Anava 95% dan analisis probit untuk menentukan LT50 (Lethal Time 50). Hasil penelitian menunjukkan bahwa jamur B. bassiana isolat Jati Sari memiliki patogenisitas tertinggi dengan membunuh kepik hijau (N. viridula) sampai 100% pada hari ke-5 HSP (hari setelah perlakuan), sedangkan isolat lain semuanya pada hari ke-6 HSP. Nilai LT50 (waktu yang dibutuhkan untuk membunuh 50% serangga uji) terdapat pada isolat P. pallicornis yaitu 2,1 hari. Persentasi mortalitas pada hari ke-3 HSP tertinggi terdapat pada perlakuan isolat P. pallicornis dengan rata-rata mortalitas sebesar 78% diikuti isolat L. acuta dan S. coarctata masing-masing sebesar 68% dan isolat Jati sari sebesar 58%, sedangkan mortalitas terendah terdapat pada perlakuan isolat WBC yaitu sebesar 32%. Tidak ada perbedaan patogenisitas yang signifikan diantara isolat Jati Sari, P. pallicornis, L. acuta maupun S. coarctata kecuali isolat WBC.Kata kunci: Beauveria bassiana; Entomopatogen; Nezara viridula Pathogenicity of Beauveria bassiana (Bals.) Viull. Isolated from Several Host Species Against Green Ladybug, Nezara viridula L. (Hemiptera: Pentatomidae) ABSTRACTGreen Ladybugs (Nezara viridula L.) are important pests for several food crops such as soybeans, rice and corn. One of the efforts to control this pest is the use of entomopathogens, such as viruses, bacteria and fungi. One of the entomopathogenic fungi that has the potential to be exploited is the fungus Beauveria bassiana. The fungi B. bassiana has various of hosts. There are no data on the pathogenicity of B. bassiana isolated from several host species against green ladybugs (Nviridula), for that reason this study was conducted with the aim of knowing the pathogenicity of B. bassiana isolated from different hosts against green ladybugs (N. viridula).. This research was conducted at Laboratory of Biological Control Agents, the Center for the Protection and Quality Testing of Food Crops and Horticulture, the Regional Agriculture and Livestock Service Office of North Sulawesi Province. The research was conducted in-vitro using a completely randomized design (CRD) with 6 treatments, namely (Negative control, N1: suspension B. bassiana, WBC isolate (brown planthopper), N2: B. bassiana suspension, Jati Sari isolate as a positive control (Ministry of Agriculture Recommendation), N3 : B. bassiana suspension isolate Paraeucosmetus pallicornis (black ladybug), N4: suspension B. bassiana isolate Leptocorisa acuta (Rice ear bug) and N5: suspension B. bassiana isolate Scotinopara coarctata (rice black bug) Treatment using conidia concentration or density 109 / ml water, with 5 replications. Data were analyzed with Anava test 95% and probit analysis to determine LT50 (Lethal Time 50). The results showed that the fungus B. bassiana Jati Sari isolate had the highest pathogenicity, because this isolate was able to kill green ladybugs (N viridula) to 100% on the 5th day of DAT (the day after treatment), while the other isolates were all on the 6th DAT. While the value of LT50 (time needed to kill 50% of the insect test) was found in P. pallicornis isolates which were 2,1 days of DAT. Because LT50 in all isolate treatments was between the 2nd and 3rd day of DAT, the Anava test for mortality was carried out on the 3rd day of DAT. The highest percentage of mortality on the 3rd day of DAT was found in the treatment of P. pallicornis isolates with an average mortality of 78% followed by L. acuta and S. coarctata isolates each at 68% and Jati sari isolates at 58%, while the lowest mortality was found in the treatment of WBC isolates, namely 32%. There was no significant difference in pathogenicity between Jati Sari, P. pallicornis, L. acuta and S. coarctata isolates except for WBC isolates.Keywords: Beauveria bassiana; Entomopatogen; Nezara viridula