Occurrence of Heavy Infestation by the Fall Armyworm Spodoptera frugiperda, a New Alien Invasive Pest, in Corn Lampung Indonesia

The fall armyworm Spodoptera frugiperda has spread and damaged corn in many African and a few Asian Countries recently. A recent outbreak (2019) of Spodoptera species in corn producing areas in the Island of Sumatra was suspected to be a new invasive species. Field observations were made on May 16, 2019 in the District of East and Central Lampung to identify the attacking Spodoptera species, and to observe and determine the damages. Based on the morphological characteristics, the “Y” inverted shape on the head capsule and the patterns of black spots on the abdominal segments (square and trapezoidal forms), the species was confirmed as S. frugiperda. The larvae heavily damaged the early stage of corn (approximately 2-week old) with 100% plants infested and each plant was occupied by a medium or large larva; while older corn received less damage. Larvae fed on the leaves causing defoliation before feeding on the growing point. Different damage symptoms due to S. frugiperda were compared to those of the Asian corn borer, Ostrinia furnacalis, and further discussion was made to determine the potential consequences of this new threat to the corn production in Indonesia.

Determination of thermal constant and development threshold of Bihar hairy caterpillar, Spilarctia obliqua Walker

Effect of six constant temperatures viz., 18±1, 21±1, 24±1, 27±1, 30±1 and 33±10C was studied on the egg hatchability, larval pupal development and adult survival of Spilarctia obliqua. Development rate of egg, larva and pupa gradually increased with increase in temperature, while total developmental period decreased. Mean developmental period of the pest decreased from 93.73 days at 18±10C to 31.20 at 33±10C. The lowest and the highest temperatures at which no development took place were found to be 12±10C and 39±10C, respectively. Regression equations between development rate and temperature were found to be Y= 0.0189 X -0.1998 (R2=0.88) for egg, Y=0.00122 X -0.0248 (R2=0.84) for small larva (1-3rd instar), Y=0.0058 X -0.0675 (R2=0.76) for large larva (4-6th instar), Y=0.0074 X-0.1075 (R2=0.94) for pupa and Y=0.0142 X-0.4363 (R2=0.79) for adults. Developmental threshold were determined to be 10.57, 11.27, 11.55, 15.28 and 10.92oC for egg, small larva, large larva, pupa, and adult respectively with corresponding thermal constant being 52.91, 344.82, 243.90, 142.85 and 70.42 degree days (DD). Thermal constant to complete a generation was found to be 854.90 DD. This was the first studies on this aspects, these estimated thermal thresholds and degree days could be used to predict the S. obliqua activity in the field for their effective management through pest forecasting.

Atrazine exposure increases time until cannibalistic response in the widow skimmer dragonfly (Libellula luctuosa)

Agricultural runoff containing herbicide is known to have adverse effects on freshwater organisms. Aquatic insects are particularly susceptible, and herbicide runoff has the potential to affect behavior in this group. Here we examine the effects of short-term exposure to the herbicide atrazine on cannibalistic behavior in larvae of the widow skimmer dragonfly (Libellula luctuosa Burmeister, 1839). Large larvae (>12 mm length) were exposed to concentrations of 0, 1, 10, or 100 μg/L atrazine for 96 h. A smaller (<8 mm) conspecific was then placed with the large larva and the behavior of the large larvae was observed for 30 min. Time until initiation of stalking and time until strike were determined. After the initial 30 min, each pair was checked at 2, 4, 6, 24, and 48 h. Time of consumption and amount consumed were determined. The number of larvae that engaged in cannibalistic activity within the initial 30 min observation period was significantly higher for controls compared with all experimental treatments. When stalking, striking, and consumption times were examined together (a measure of overall response time), concentration had a significant effect with the 10 μg/L group taking significantly longer to cannibalize than the control group. Cannibalism is a particularly important behavior in dragonfly larvae populations, and this study confirms that this interaction is altered by exposure to atrazine, with the potential to affect ecological relationships.