Comparative Karyology of Philippine Black Bugs (Hemiptera: Pentatomidae) Sampled from the Bicol
Region and Laguna
Approximately 2.3 million ha or 25% of total arable land in the Philippines is devoted to rice cultivation.
Such importance is given to the production of this crop because rice serves as the most important
carbohydrate-rich food crop in the country as well as in other Asian nations (Heinrichs 1994).
Unfortunately, a percentage of the annual rice production is lost to insect damage. So far, around 100
species of insects have been identified as rice pests. Twenty of these were classified as major pests (e.g.,
rice leafhoppers and planthoppers), while additional threats to yield loss are reported by Pathak and
Khan (1994) to be caused by what is termed as minor pests (e.g., whorl maggots and rice bugs).
Comparative Karyology of Philippine Black Bugs (Hemiptera: Pentatomidae) Sampled from the Bicol
Region and Laguna Aimee Lynn A. Barrion-Dupo, Frances Gerard DM. Genil, Luisa N. Villamael, and
Adelina A. Barrion 192 RICE BLACK BUGS Taxonomy, Ecology, and Management of Invasive Species The
rice black bugs (Hemiptera: Pentatomidae) in many rice-growing regions in the Philippines manifested
significant geometric increases in number and therefore alarmed rice growers. These black bugs
attracted much interest since the detection in February 1982 of the Malayan black bug, Scotinophara
coarctata (Fabricius) in southern Palawan (Barrion et al. 1982). Then, on 8 June 1982, a report of the
Malayan black bug from the Bureau of Plant Industry at Los Baños led Barrion and Litsinger (1987) to
sample the black bugs from Siniloan, Laguna, near Laguna de Bay and study their bionomics, karyology,
and chemical control. The species was identified as the node-feeding black bug, Scotinophara latiuscula
(Breddin). Recently, in 2006, black bug outbreaks occurred in more than 1,338 ha in 29 municipalities of
saprophytic black bugs were sampled by PhilRice consultant, Dr. A.T. Barrion, from rice stubbles in San
Roque, Sangay, Camarines Sur; Tulangan, Matnog, Sorsogon; Bagacay, Gubat, Sorsogon; Gadgaran,
Matnog, Sorsogon; Balading, Tabaco, Albay; and Nagas, Tiwi, Albay. From the field collections of black
bugs, the adult males were used for karyological investigation. Karyology refers to a cytological study
focusing on the nuclear features (e.g,. chromosomes) of the eukaryotic cells of the species. The nuclear
chromosomes are the carriers of genetic materials of the species and, although mutable, they are
basically stable intraspecifically. In modern systematics, karyological characters are considered useful in
describing and differentiating species. In this study, the karyology of the two black bug species, S.
coarctata and S. latiuscula, were determined and compared. These include meiotic index, chromosome
number, relative length of pachytene chromosomes, and behavior of meiotic chromosomes.
Rice (Oryza sativa L.) is the staple food among Filipinos as well as in many other Asian nations. It
provides about 80% of the calories of most Asians and one-third of the calorie intake of about a billion
people in Africa and Latin America (Heinrichs 1994). A major factor that significantly limits rice
production is infestation by more than 100 insect pests, 20 of them are major pests. Later, minor pests
such as rice bugs, rice leaffolders, and whorl maggots became more important (Pathak and Khan 1994).
Isozyme Polymorphism in Rice Black Bug Scotinophara sp. (coarctata group) (Hemiptera: Pentatomidae)
Sampled from Rice Fields in the Bicol Region Frances Gerard dM. Genil, Rosalinda N. Tandang, Adelina A.
Barrion, Alberto T. Barrion, Ravindra C. Joshi, and Leocadio S. Sebastian RBB Book.indb 203 10/3/2007
11:46:13 AM1 204 RICE BLACK BUGS Taxonomy, Ecology, and Management of Invasive Species It was in
February 1982 when the Malayan black bug, Scotinophara coarctata (Fabricius), was initially detected in
the rice fields of southern Palawan. The bug was not included in the faunal list of arthropods injurious to
Philippine crop plants (Woodworth 1921, 1922 a&b, Capco 1957, Cendana and Calora 1967, Baltazar
1968, Gabriel 1975). Then, on 8 June 1982, a report from the Bureau of Plant Industry at Los Baños led
the researchers A.T. Barrion and J.A. Litsinger of the International Rice Research Institute (IRRI) to an
irrigated wetland site in Siniloan, Laguna, near Laguna de Bay where another species of rice black bug,
Scotinophara latiuscula (Breddin), was observed to be causing deadheart damage to rice. Their intensive
research on the species from June 1982 to February 1984 enabled them to document the bionomics,
karyology, and chemical control of the node-feeding bug S. latiuscula (Hemiptera: Pentatomidae) in the
Philippines (Barrion and Litsinger 1987). Six Scotinophara species have been recorded in the Philippines:
S. cinerea Le Guillou (Hasegawa 1971); S. ochracea (Distant) and S. lurida (Burmeister) (Wongsiri 1975);
and S. latiuscula (Breddin), S. serrata (Vollenhoven), and S. tarsalis (Vollenhoven) (Miyamoto et al 1983).
None of these species have ever been reported as rice pest. The outbreaks of black bugs occurred in
provinces such as Zamboanga and Sorsogon in 1992 and Negros Occidental in 1998. Recently, in 2006,
outbreaks were recorded in Capiz, Iloilo, and Bicol. RBB infestations were noted in four provinces in
Bicol, namely: Sorsogon, Albay, Catanduanes, and Camarines Sur where more than 1,338 ha in 29
municipalities were reported (UMAsenso 2006). The alarming outbreaks of RBBs in many rice-growing
sites in the Philippines prompted many researchers to conduct scientific investigations regarding the
insect species. Since no molecular information has yet been reported on RBBs sampled from the Bicol
Region, this study was conducted. The foundation knowledge would serve as basis for future studies
about the pest. The study aimed to investigate the isozyme polymorphism of the RBBs from five
different localities in Bicol: San Roque, Sangay, Camarines Sur; Tulangan, Matnog, Sorsogon; Bagacay,
Gubat, Sorsogon; Balading, Tabaco, Albay; and Nagas, Tiwi, Albay (Fig. 1). The specific objectives are to
identify the isoloci of three enzymes—acid phosphatase (ACPH), alkaline phosphatase (ALPH), and
esterase (EST)—and estimate gene and genotypic frequencies; to determine genetic variability by
calculating the degree of polymorphism, average number of alleles per locus, and average
heterozygosity within the population. The genetic similarities and distance of the populations of
Scotinophara sp. from the different localities of the Bicol Region were determined.
Indonesia’s 11-year (1989–1999) National Integrated Pest Management Program was a spectacularly successful
example of wide-scale adoption of integrated pest management (IPM) principles and practice in a developing country.
This program introduced the innovative Farmer Field School model of agro-ecosystem-based experiential learning,
subsequently adapted to different crops and agricultural systems in countries throughout the world. Since the
termination of the program in 1999, Indonesia has undergone profound changes as the country enters a new era of
democratic reform. Government support for the national IPM program has wavered during this period, and pesticide
producers and traders have taken advantage of the policy vacuum to mount an aggressive marketing campaign in the
countryside. These factors have contributed to a reappearance of the pesticide-induced resurgent pest problems that
led to the establishment of the National IPM Program in the first place. View Full-Text
Keywords: integrated pest management (IPM); rice; rice brown planthopper (BPH); nilaparvata
lugens stål; insecticide-induced resurgence; Indonesia