Functional Response of Hyperaspis polita (Coleoptera, Coccinellidae) to the Recently Invaded Mealybug Phenacoccus solenopsis (Hemiptera, Pseudococcidae)

Hyperaspis polita Weise is the major predator of Phenacoccus solenopsis Tinsley in southwestern Iran. The functional response of fourth instar larva, adult female and male of the ladybird, H. polita, preying upon different stages of the mealybug P. solenopsis was evaluated. All stages of H. polita exhibited type II functional responses against all stages of P. solenopsis with an exception that the functional response of the adult female stage of H. polita to first instar P. solenopsis nymphs was type III. Changing prey and predator stages did not result in significant differences in attack rates. Handling times, however, differed for different prey and predator stages. This parameter was the shortest for any stage of predator fed on first instar P. solenopsis nymphs and was estimated to be 0.1100, 0.1868, and 0.2939 h for fourth instar larval stage, adult females and males, respectively. Also, the handling time was the shortest for the fourth instar larval stage followed by adult females and males to different prey stages. Maximum predation rate (T/T_h) decreased as P. solenopsis developed from one life stage to another, the lowest estimated value being obtained by feeding on adult female mealybug and the fourth instar larval stage was the most predatory. According to these results, the feeding potential of H. polita is noticeable with the fourth larval instar stage being considered the most efficient predatory stage for use in biological control programs. Further field-based studies are needed, however, before a comprehensive estimation of the biocontrol abilities of H. polita toward P. solenopsis can be made.

Interactions between Entomopathogenic Fungus, Metarhizium anisopliae and Sublethal Doses of Spinosad for Control of House Fly, Musca domestica

BACKGROUND

Metarhizium anisopliae strain IRAN 437C is one of the most virulent fungal isolates against house fly, Musca domestica. The objective of this study was to determine the interaction of this isolate with sublethal doses of spinosad against housefly.

METHODS

In adult bioassay, conidia of entomopathogenic fungus were applied as inoculated bait at 10(5) and 10(7) spore per gram and spinosad at 0.5, 1 and 1.5 μg (A.I.) per gram bait. In larval bioassay, conidia were applied as combination of spore with larval bedding at 10(6) and 10(8) spore per gram and spinosad at sublethals of 0.002, 0.004 and 0.006 μg (AI) per gram medium.

RESULTS

Adult mortality was 48% and 72% for fungus alone but ranged from 66-87% and 89-95% in combination treatments of 10(5) and 10(7) spore/g with sublethal doses of spinosad respectively. The interaction between 10(5) spore/g with sublethals exhibited synergistic effect, but in combination of 10(7) spore in spite of higher mortality, the interaction was additive. There was significant difference in LT(50) among various treatments. LT(50) values in all combination treatments were smaller than LT(50) values in alone ones. Larval mortality was 36% and 69% for fungus alone but ranged from 58%-78% and 81%-100% in combination treatments of 10(6) and 10(8) spore/g medium with sublethals of spinosad respectively. The interaction was synergistic in all combination treatments of larvae.

CONCLUSION

The interaction between M. anispliae and spinosad indicated a synergetic effect that increased the house fly mortality as well as reduced the lethal time.

Foraging population and territory estimates for Microcerotermes diversus (Isoptera: Termitidae) through mark-release-recapture in Ahwaz (Khouzestan, Iran)

Microcerotermes diversus Silvestri (Isoptera: Termitidae), an important pest in Ahwaz (Khouzestan, Iran), causes serious economic damage to wooden products in buildings. In this study, we determined the foraging populations and territories of this species using mark-release-recapture techniques. Based on both the weighted mean model and Lincoln index methods, mean termite foraging population estimates for two colonies, A and B, were 2,984,489 +/- 258,802 and 326,134 +/- 8,713, respectively. Estimates with the Lincoln index were 2,731,229 +/- 813,081 for colony A and 321,493 +/- 138,499 for colony B. Estimated horizontal foraging territories for colonies A and B were 25.59 and 44.16 m2, respectively. The maximum and minimum linear foraging distances were 5.40 and 2.14 m for colony A and 9.14 and 1.86 m for colony B, respectively. Our data expand the knowledge about the biology, ecology and behavior of M. diversus.