H.armigera egg parasitoid
egg parasitoids consist of Trichogramma
sp. and T. armigera. Trichogramma
sp. parasitoid is a solitary parasitoid, whereas T. armigera
is a solitary and gregarious one. Trichogramma
sp. produces female offspring while T. armigera
produces male and female ones. Trichogramma
parasitoids were not found Kakas, Tomohon Timur and, Motoling. Conversely, T. armigera
was found in all locations.
sp. was not parasitized C. cephalonica
host eggs, however, the parasitoid T. armigera
can parasitize C. cephalonica
sp. parasitoid is included in Thelytokous parthenogenesis. Huigens and Stouthamer (2003)
stated that Wolbachia is common in female insects, female parasitoids infected with Wolbachia happen to the thelytoky parasitoid and female offspring. Hoffmann et al., (2001)
added that females infected with Wolbachia bacteria produce fewer female offspring than uninfected parasitoids. The population of T. kaykai
parasitoids infected with Wolbachia is low (Russel et al., 2018).
The population of Trichogramma
sp. was 2-8 individuals in each egg sampling, while more than 10 individuals of T. armigera
were taken. T. armigera
parasitosoid is a reddish-brown parasite with the dark brown middle coxa. Its thorax is dark brown with a darker abdomen. Its antenna is yellow with the last club-shaped segment, the front wing has a slight trichia and long fringe setae. Its female length is 0.42 mm± 0.02 mm and 0.39 mm±0.02 mm for the male. Trichogramma
sp. yellowish color, head, thorax, yellow antenna and the last segment is club-shaped. The abdomen has a brown transverse strip and a brown abdomen tip. The front wing has many trichia and fringe setae rather long and the length of the female (0.49 mm±0.02 mm). Parasitic eggs turn black, while healthy eggs turn yellowish-white to hatch into larvae. The Chi-square analysis of parasitism for those without coconut palm shade was not significantly different from 45 DAP (÷2 =9.600; p>0,087), but 55 DAP was different (÷2 =15.222; p < 0,009) (Table 3).
Table 3: The parasitism H.armigera egg in the corn plant without coconut palm shade.
Parasitism data provided a significant influence for corn cobs borer since, during the research, severe damage to the cobs had not been found. Parasitoid surveys without shading had a higher tendency of parasitism at 45 DAP. 55 DAP parasitism was low, female flowers might have 40-50 % dry and turned brownish to black. Thus, it might not be attractive for parasitoids to find the eggs. Around the study location, corn plants with red female flowers were found, which easily attracted the parasitoids. Red female flowers in H. armigera
population tends to be higher than brown female flowers.
The highest parasitism without coconut shade in Bolaang (36.46±5.18%). H.armigera
population in Bolaang is relatively high compared to other locations. Thus, it is concluded from this experiment that parasitism correlated with the number of host eggs. Population density of the host is an important aspect that influences the high parasitism (Montoya et al., 2000; Jones et al., 2003). Romeis et al., (1999)
said that Trichogramma
sp. parasitism to H.armigera
eggs depends on the location and number of host eggs. Generalist parasitoid is higher in polyculture plantations compared to monocultures (Menalled et al., 1999).
Unlike in Kakas, the number of eggs tends to be high, but the parasitism of T. armigera
is not maximal. The laboratory experiment revealed that parasitoid efficiency decreases with a decrease in temperature (Mills and Getz, 1996)
. Besides egg density, the difference in parasitism is also influenced by microclimate, geographical location and plant cultivation practice. The Results of parasitism indicated that changes in weather factors as a result of climate change would have considerable influence on survival and development of parasitoids (Kuzhandhaivel et al., 2016).
Parasitism for those with coconut palm shade is higher than without those shade. Parasitism with the highest shade is in Bolaang (60.91±2.52%) (Table 4).
Table 4: Parasitism of H.armigera eggs in corn plants with coconut palm shade.
In Bolaang, in addition to coconut plants, banana and mango trees are found in maize plantations that also affect microclimate. Liu et al., (2016)
stated that heterogeneous landscapes could effectively increase H. armigera
parasitoids in cotton plants. Data obtained suggest that the ecological influence for biological control through conservation is needed for non-corn plants. In Kakas, Tomohon and Motoling, corn was planted without shade, because of the lack of coconut plantations. The Chi-square analysis showed significant differences in parasitism of the 45 DAP (÷2 =20.397; p< 0,000, 55 DAP ÷2 =10.047; p<0,007) (Table 4).
The shade density of coconut palm plants in Bolaang is irregular (3 m x 3 m and 3 m x 4 m), while in Poigar it was 6 m x 6 m, in East Dumoga Timur was 5 m x 5 m and 5 m x 6 m. Shade density in Bolaang is denser, thus affecting the microclimate to be cooler and temperatures to be lower, this has an impact on parasitism being high. Microclimate change causes the temperature of maize polyculture to be lower, while without shade the temperature becomes high. Change in microclimate is shown in tea plants, air temperature of tea plants without a shade is 27°C and with the shade of 24°C, humidity is 48% to 74% (Widayat and Rayati, 2011)
. Geetha and Balakrishnan (2010)
stated that cooler microclimates affect T. chilonis
parasitism and better spread.
C. cramerella egg parasitoids
egg parasitoids are Trichogrammatoidea
sp, obtained through C. cramerella
egg trap. However, there were only two C. cramerella
eggs we parasitized from 4 times of cacao sampling. The parasitoid morphology of Trichogrammatoidea
sp. on C. cramerella
eggs is the same as C. cephalonica
egg traps. The parasitoid is brownish yellow, the head is brownish yellow and the abdomen has dark patches, the antenna is with a long tassel and the middle coxa is dark brown. Female antennas are in the form of a club, whereas males are not big, but have long hair. The front wing with fringe setae, long tornus section and little trichia on a remigium. The C. cramerella
egg parasites are Trichogrammatoidea bactrae fumata, Trichogrammatoidea cojuangcoi
and Trichogramma chiolonis. (Alias et al., 2004)
Parasitism shows that the population of Trichogrammatoidea
sp. in cocoa plantations is relatively low. The effective monitoring of these parasitoids is the C. cephalonica
egg traps. In Passi and Poigar, the Trichogrammatoidea
sp. parasitoid through C. cramerella
eggs have not been found. It was found in Tombariri. C. cramerella
‘s parasitized eggs turn from orange to black (Table 5).
Table 5: Eggs are parasitized on plastic cards and parasitized eggs.
egg trap is an active trap that uses an agent to attract parasitoids in yellowish-white color. Traps are active with chemical and physical stimuli in the forms of light, color, or chemical compounds making insects are attracted to the trap (Yi et al., 2012).
The reported parasitism on the card containing C. cephalonica
eggs is very low. Low levels of C. cephalonica
eggs parasitized reported by Kandowangko et al., (2015).
All parasitized C. cephalonica
eggs that are bred can become imago parasitoids. However, the dominant population is male as an indication of low parasitism since the parasitoid that parasitizes the egg is female. Dolichodorus
sp and spiders which are predators of C. cephalonica
eggs were found in cocoa plant ecosystems. Thus, it consequently affected the low parasitism.
eggs can be used to monitor C. cramerella
parasitoids. The cost for C. cephalonica
egg traps is relatively cheaper than cocoa taking. Besides that, the parasitized eggs of C. cephalonica
are more easily detected. In Malaysia, to obtain information on T. bactrae fumata,
yellow and green cylindrical contacts are used. Green is more attractive than yellow (Azhar and Long, 2004)
. The use of the cylindrical trap method is inappropriate since the trapped parasitoids cannot be bred as they have died.