The big-eyed bug, Geocoris ochropterus Fieber, is a polyphagous predator. Although there have been many publications on the rearing of big-eyed bugs by using other insects, their ability to use flowers as a source of nutrition or habitat has not been previously reported. The diets included Zinnia elegans (A), 10% honey solution (B), ant pupae and Zinnia elegans (C), mealybug and Zinnia elegans (D) treatments at 10°C, 20°C, and 30°C. Significant differences in survival rates were observed among the diets when the nymphs reached the 1st and 2nd instars at 10°C. Significant differences in growth and development indicators of big-eyed were found among the treatments during the 2nd, 3rd, 4th, and 5th molts at 30°C. Additionally, body size and dry weight of adult G. ochropterus grown on different diets were measured at 20°C and 30°C. At 20°C, male body size parameters did not significantly differ among the diets, except for head width. At 30°C, body length and dry weight of males showed significant differences among the diets, while head width and dry weight of females also varied significantly among diets. The study indicates that the combination of floral resources and diet can affect the development of G. ochropterus at different temperatures.

Insects

Geocoris ochropterus was collected in Cu Chi district, Ho Chi Minh city and reared in the laboratory (Chau et al., 2021, 2023) using ant pupae Oecophylla smaragdina as food source to collect eggs for experiments.

Diets resources

The diets used ant pupae Oecophylla smaragdina (Hymenoptera: Formicidae) purchased from Minh Nhat fishing shop, Cu Chi district, Ho Chi Minh City store in Thu Dau Mot, Binh Duong province, Vietnam. Adult mealybugs Planococcus citri were reared and maintained on fresh pumpkins in the laboratory. Flowers of common zinnia (Zinnia elegans) were choose (Han et al., 2024) and grown from seeds sown in 50 x 50 cm polybags. The plants flowered prolifically and produced florets throughout the experiment. Honey was purchased from the supermarket (U Minh honey – Viethoney) and diluted with water.

Experiment design

The experiment was conducted in the XINGCHEN GZX-150B growth chamber from April to August 2023. Newly hatched first-instar G. ochropterus were separately provided with different diets, including: flower Zinnia elegans (n=25) (Treatment A); 10% honey solution (n=25) (Treatment B); ant pupae and Zinnia elegans (n=25) (Treatment C); adult mealybugs and Zinnia elegans (n=25) (Treatment D); and each instar was reared in a plastic jar (Bottom diameter is 85mm x height 150mm x top diameter is 117mm) containing a piece of cotton soaked with water (Figure 1). The hydroponic solution used in the experiment is Lavamix Hydroponic (Duc Thuan Trading & Service Company Limited, Vietnam).The food source was ant pupae supplemented at 50 g per day, mealybugs at 10 individuals per day, 10% honey solution at 1 ml per day, and the lowers were replaced every 4 days to ensure freshness.

All treatments were conducted at constant temperatures of 10 ± 1°C, 20 ± 1°C, and 30 ± 1°C, with 70 ± 5% relative humidity and a photoperiod of 16 hours light and 8 hours dark in a growth chamber (RGX-150B, Xingchen, China) at the Laboratory of Animal Science, Faculty of Biotechnology, Ho Chi Minh City Open University, Vietnam.                            

The development time of each stage and survival rate (from first instar to adult) were recorded. The nymphal survival rate was calculated as the number of individuals that molt at each larval stage divided by the total number of eggs hatched.

Morphological measurements

According to Chau et al. (2021), the body size of one-day-old adults was measured with the following parameters: head width (from the compound eye), body length (from the anterior tip of the head to the posterior tip of the abdomen), and forewing length (from the posterolateral edge of the forewing to the tip of the forewing), individually using a digital ruler (Mitutoyo Corporation No. 99MAC005B).

 Statistical analysis

Development time and survival rate were analyzed by using two-way factorial ANOVA to assess the differences between temperature and food source groups, and also to test the interaction between these two factors with SPSS 22.0, followed by Tukey’s post-hoc test for multiple comparisons to compare treatment means.

For the statistical comparison of body size and weight, the statistical method used was Dunnett's Two-Sided T-Test.