Effect of Larvae Treated with Mixed Biopesticide Bacillus thuringiensis - Abamectin on Sex Pheromone Communication System in Cotton Bollworm, Helicoverpa armigera

Third instar larvae of the cotton bollworm (Helicoverpa armigera) were reared with artificial diet containing a Bacillus thuringiensis - abamectin (BtA) biopesticide mixture that resulted in 20% mortality (LD(20)). The adult male survivors from larvae treated with BtA exhibited a higher percentage of “orientation” than control males but lower percentages of “approaching” and “landing” in wind tunnel bioassays. Adult female survivors from larvae treated with BtA produced higher sex pheromone titers and displayed a lower calling percentage than control females. The ratio of Z-11-hexadecenal (Z11–16:Ald) and Z-9-hexadecenal (Z9–16:Ald) in BtA-treated females changed and coefficients of variation (CV) of Z11–16:Ald and Z9–16:Ald were expanded compared to control females. The peak circadian calling time of BtA-treated females occurred later than that of control females. In mating choice experiment, both control males and BtA-treated males preferred to mate with control females and a portion of the Bt-A treated males did not mate whereas all control males did. Our Data support that treatment of larvae with BtA had an effect on the sex pheromone communication system in surviving H.armigera moths that may contribute to assortative mating

Infrared heating as a disinfestation method against Sitophilus oryzae and its effect on textural and cooking properties of milled rice

Infrared (IR) heating method against rice weevils (Sitophilus oryzae) in an egg stage was investigated. A kinetic model was developed to describe insect mortality in a temperature range of 40-60 A degrees C. Effects of IR heating temperature (50-60 A degrees C) and exposure time (1-3 min) on insect mortality and quality attributes of the treated rice were evaluated. The optimized condition obtained by means of the response surface method was used to analyze rice quality before and after IR treatment with storage. The results showed that the 0.5th-order thermal death kinetic equation was the most suitable model, and the S. oryzae eggs had less heat tolerance than the adults and some other species. Mortality achieved 100 % after 2 min for all temperatures. Both IR heating parameters significantly affected the treated milled rice qualities. The minimal changes in rice quality before and after storage could be obtained using optimized temperature and exposure time of 53.6 A degrees C and 1.2 min, respectively

Excision of <i>H.armigera</i> sex pheromone gland for being extractioned.

<p>(a) ovipositor; (b) gland; (c) cuticle.</p

Behavioral responses of male moths to a pheromone lure in the wind tunnel bioassays.

<p>In lure (filter paper), the dosage of sex pheromones was 300 ng with the 97∶3 blend of Z11–16:Ald and Z9–16:Ald. Five parameters taken in the wind tunnel: TF = taking flight, OR = orientation flight, HW = half up-wind to lure, APP = approaching the cage containing the lure (within 10 cm), LA = landing on the cage containing the lure. The data marked with “*” and “**” are significantly different at P<0.05 and P<0.01 as shown by a χ² test.</p

Mating choice experiment of <i>Helicoverpa armigera</i> with two groups.

<p>Mating choice experiment of <i>Helicoverpa armigera</i> with two groups.</p

Calling percentages of female moths.

<p>The moths were recorded as calling or not calling during a 10-h scotophase after treating 3rd instar larvae with BtA artificial diet (N = 30) or standard artificial diet (N = 30). The data (Mean±SEM) marked with “*” and “**” are significantly different at P<0.05 and P<0.01 based on student’s t test after mean percentages were arsine square-root transformed.</p

Five parameters used in the wind tunnel bioassay: take flight (TF), orientation (OR), half up-wind to lure (HW), approaching the cage containing the lure (within 10cm) (APP), landing on the cage containing the lure (LA).

<p>Five parameters used in the wind tunnel bioassay: take flight (TF), orientation (OR), half up-wind to lure (HW), approaching the cage containing the lure (within 10cm) (APP), landing on the cage containing the lure (LA).</p